Course 3 Flashcards

Question

What are the hormones of adrenal medulla?

Answer 1

catecholamines, tyrosine derivatives - adrenalin (epinephrine) 􏰀 mobilization of glucose and FA into the bloodstream (via β-adrenergic receptors) - fight-or-flight reaction o ensures survival - fighting, fleeing, feeding and mating - noradrenalin (norepinephrine) 􏰀 contraction of smooth muscles of the skin and intestinal tract (via α adrenergic receptors)

Answer 2

- steroids - testosterone (testes) 􏰀 controls the male sexual differentiation and function of the male genital organs - estradiol (ovaries) 􏰀 controls the female sexual differentiation and function of female genital organs - progesterone (ovaries, placenta) 􏰀 maintain pregnancy

Answer 3

- proteins and peptides - insulin 􏰀 regulates carbohydrate, lipid and protein metabolism 􏰀 lowers blood glucose - glucagon 􏰀 insulin antagonist

Answer 4

- chemical character of cytokines - proteins o groups of cytokines - a) growth factors, b) lymphokines and monokines, c) interferons and d) other cytokines

Answer 5

mainly regulation of cells of nonhemopoietic origin (everything except platelets and red blood cells and white blood cell)

Answer 6

TGF-β (transforming growth factor β􏰂 􏰀 produced in various types of cells (platelets) o Inhibition and stimulation of proliferation of various types of cells

Answer 7

EGF (epidermal growth factor) 􏰀 produced in various types of cells (submandibular gland, macrophages) o Stimulation of epithelial cell proliferation

Answer 8

FGF-1 (fibroblast growth factor 1) 􏰀 produced in brain tissue o Stimulation of proliferation of various types of cells (fibroblasts)

Answer 9

FGF-2 (fibroblast growth factor 2) 􏰀 produced in nerve tissue o Similar as to FGF-1 stimulates different type of cells

Answer 10

HGF (hepatocyte growth factor) 􏰀 produced in cells of mesodermal origin (platelets, macrophages) o Stimulation of hepatocyte proliferation

Answer 11

IGF-I (insulin-like growth factor 1) 􏰀 liver is the main place of production o Stimulation of proliferation of most cell types o Very important 􏰀 can not live without it

Answer 12

IGF-II 􏰀 again main place of production is the liver o Biological effects similar to IGF-I, however acts prenatally

Answer 13

NGF (nerve growth factor) - produced in various types of cells (smooth muscle cells, epithelial cells o Sustaining of viability of embryonic neurons (works as a survival factor)

Answer 14

PDGF (platelet-derived growth factor) 􏰀 produced in plateletes o Stimulates proliferation of dermal fibroblast o Large role in wound healing thrombocytes release PDGF, which stimulaters fibroblast to proliferate and produce extracellular matter that clogs the wound in the skin

Answer 15

Mainly regulation of cells of haemopoietic origin (platelets, red blood cells and white blood cells) , produced mainly in lymphocytes and monocytes

Answer 16

IL-1 (interleukin 1) produced in activated macrophages o Mediating of immune response and inflammatory response (inflammation = high level of IL-1)

Answer 17

IL-2 produced mainly in activated T lymphocytes o Stimulation of proliferation and differentiation of T cells

Answer 18

- IL-3 produced mainly in T lymphocytes o Stimulation of proliferation and differentiation of haemopoietic progenitor cells

Answer 19

- IL-4 􏰀 produced mainly in activated T lymphocytes o Stimulation of proliferation and differentiation of B cells

Answer 20

IL-5 􏰀 produced mainly in T lymphocytes o Stimulation of proliferation and differentiation of eosinophils (allergy)

Answer 21

GM-CSF (granulocyte-macrophage colony stimulating factor) 􏰀 produced in various types of cells (macrophages), o stimulation of proliferation of various types of haemopoietic cells

Answer 22

- antiviral activity and inhibition of cell proliferation - INF-α (interferon alfa􏰂 􏰀 produced in leukocytes o Antiviral effects and inhibition of proliferation of various types of cells and also immunomodulatory activity - INF-β 􏰀 produced in fibroblasts o Biological effects similar like IFN-α - INF-γ 􏰀 produced in T cells o Antiviral effects and inhibition of tumor cell proliferation and also immunomodulatory activity o Belongs to a different family than INF-α and INF-β

Answer 23

- erythropoietin (EPO) ʹ produced in kidneys o stimulation of proliferation and differentiation of erythroid progenitor cells (ensures the development of erythrocytes) o during hypoxia increases the production of EPO production and thus increases the amount of red blood cells - TNF-α (tumour necrosis factor α; cachectic) ʹ produced in macrophages o Induction of cell death (tumour cells o Causes cachexia (weakness , congestion) in the final stages of cancer ʹ killing all cells - TNF-β (lymphotoxin) ʹ produced in lymphocytes o Biological effects similar to TNF-α - growth hormones (GH) ʹ has some characteristics to cytokines, including recepotrs

Answer 24

- chemical character of neurotransmitters: amino acids, amines etc. - acetylcholine ʹ choline derivative, direct interaction with ion channels (ligand ʹ gated ion channels) - GABA (γ-aminobutyric acid) ʹ biogenic amine, glutamate derivative, direct interaction with ion channels - dopamine ʹ tyrosine derivatives, belongs to catecholamine family, interaction with receptors associated with G proteins - serotonin ʹ tryptophan derivative, interaction with receptors associated with G proteins

Answer 25

- chemical character of retinoids - vitamin A (retinol) - retinoic acid ʹ retinol derivative, regulation of embryonic development (morphogen)

Answer 26

- cholesterol is in cell membranes it stabilizes membrane and lower its fluidity o forms around 1/4 of all lipids in membranes - has an amphipathic character (both polar and nonpolar) - is a precursor to many significant derivatives o bile acids ʹ die to their amphipathic nature, they can interact with both water and food in the intestine their effect increases the surface area of fatty food, thus increasing the effect of enzyme decomposition o substances with signaling function – steroid hormones, vitamin D

Answer 27

5 main classes o gestagens - progesterone (necessary to maintain pregnancy) o androgens - testosterone (anabolic hormone, that supports secondary sexual characteristics of men) o estrogens - estriol, estradiol (supports secondary sexual characteristics of women) o glucocorticoids - cortisol (affects energy metabolism) o mineralocorticoids - aldosterone (increases the absorption of water and sodium from urine and excretion of potassium and H+ into the urine in the distal renal tubule = affects blood volume, blood pH, and plasma sodium concentration) - gestagens, estrogens and androgens are sometimes collectively referred to as sex hormones

Answer 28

- its active form is calcitriol - is not a true steroid, but has a similar mechanism of action ʹ intracellular receptor binding and gene expression regulation - Although vitamin D can be produced from cholesterol after sun exposure, it is considered to be a vitamin and therefore essential in our diet - Affects the body’s management of calcium and phosphates in the body in medicine it is used to prevent bone diseases - Its precursor 7-dehydrocholesterol -> sunlight cleaves one of its rings -> precalciferol -> cholecalciferol (inactive vitamin D3) -> hydroxylation in liver and in the kidney leaving us with calcitriol

Answer 29

Most of it takes place in the cytosol and some in ER- but not always must cholesterol be produced, individual synthesis intermediates are used for the production o other substances, e.g. ubiquinone or vitamin D

Answer 30

o 1. Synthesis of isopentenyl diphosphate - active isoprene unit (5C) - from Acetyl-CoA a large part of this phase proceeds in the same way as ketone synthesis o 2. condensation of 6 isopentenyl diphosphates into one linear molecule - squalene (30C) o 3. cyclization linear squalene undergoes a series of reactions to a tetracyclic product - cholesterol (27C)

Answer 31

- takes place in cytosol - substrate - Acetyl-CoA - intermediates - HMG-CoA (3-hydroxy-3-methylglutaryl-CoA) and mevalonate - HGM-CoA reductase ʹ key regulatory enzyme for cholesterol synthesis that reduces HGM-CoA to mevalonate

Answer 32

Cholesterol synthesis - Reverses the last β-oxidation - 2 acetyl-CoA -> acetoacetyl-CoA

Answer 33

Cholesterol synthesis -- adds a new 2C from Acetyl-CoA to acetoacetyl-CoA

Answer 34

- cholesterol synthesis - HMG-CoA reductase converts HMG-CoA to mevalonate - It is a double reduction o carboxyl group -> primary alcohol group - as a reducing agent we use 2x NADPH + H+

Answer 35

o 3x isopentenyl diphosphate (5C) Æ farnesyl diphosphate (15C) head = phosphate groups, tail = carbon chain condensation occurs between head and tail o 2x farnesyl diphosphate (15C) -> squalene (30C, linear molecules) head-to-head interaction

Answer 36

- long process, just know lanosterol ʹ 30 C intermediate, which already has 4 sterane rings

Answer 37

- an adult produces around 800mg of cholesterol in the liver and intestines daily o from food- 300-400 mg (in total we should get about 1,1 g cholesterol) - cellular cholesterol levels in the cell regulate HMG- CoA reductase synthesis - factors affecting HMG-CoA reductase 1) reductase transcription rate ʹ transcription factor = sterol regulatory element binding protein (SREBP) low cholesterol activates SREBP, high inhibits it 2) reductase translation arte ʹ inhibited by non-steroidal metabolites derived from mevalonate 3) degradation of reductase ʹ high cholesterol concentration accelerates degradation of reductase 4) reductase activity - AMP-activated protein kinase (AMPK) phosphorylates reductase and thus decreases its activity, insulin dephosphorylates reductase, thereby increasing its activity, thereby promoting cholesterol synthesis anti-cholesterol drugs target HMG ʹ CoA reductase and are called statins ʹ e.g simvastatin or lovastatin.

Answer 38

metabolism of lipoproteins - lipoproteins and proteins ʹ high molecular components of blood plasma ʹ are used for transport of lipids in plasma - ketone bodies travel freely dissolved in plasma, fatty acids are already more complex o short chain FA (up to 12C) are freely dissolved in plasma o long chain FA must be bound to protein albumin - other lipids are distributed in the body by lipoproteins - lipoproteins are spherical particles of amphipathic nature o have hydrophobic core) TAG and cholesterol ester) and a cover of amphiphilic molecules (apoporteins, phospholipids and cholesterol)

Answer 39

- are found on the surface of lipoproteins - act as membrane stabilizers, ligands for target tissue receptors and as cofactors of lipoprotein metabolism enzymes - one apoprotein may have more than one role o structural support - Apo B100 and Apo B48 o cofactors (activators) enzymes - Apo C-II (enzyme LPL) a APO A-I (enzyme LCAT) o receptor ligands - Apo B100 (LDL-receptor), Apo E (scavenger receptor), Apo A-I (HDL receptor)

Answer 40

lipoproteins which transfer TAF and cholesterol from the intestine to the tissues ( to the place of consumption or storage)

Answer 41

transport of TAG from liver to tissues

Answer 42

arise from VLDL after removal of lipid

Answer 43

transports cholesterol from the liver to the tissues this lipoprotein carries cholesterol throughout the body, contributing to atherosclerosis

Answer 44

transports cholesterol from tissues to the liver, where the liver processes them into bile acids this lipoprotein deprives the blood vessels of cholesterol and its high blood level is considered as a positive sign reducing the likelihood of atherosclerosis ( = heart attack, stroke) proteins have higher densitiy than lipids Æ higher density lipoproteins have higher % prtoeins

Answer 45

- are formed in intestinal enterocytes and serve to transport TAG and CE ( cholesterol esters) from the intestine to the tissues - they travel from the intestine first through the lymphatic pathways and through the ductus thoracicus and into the blood - they obtain Apo E a Apo C-II in the blood from HDL o Apo C-II activates lipoprotein lipase (LPL), which catalyzes the hydrolysis of TAG to FA and MAG o MFA then penetrate into tissue - Chylomicrons gradually produce chylomicrons residues, which are smaller and contain a larger proportion of CE and MAG - These residues are gradually taken up and removed by the liver (the receptor ligand is Apo E ) - In addition to Apo E a Apo C-II, chylomicrons have Apo B48 on their surface

Answer 46

- Forms in the liver and serves to transport Tag from liver to the periphery - Endothelial cells carry LPL (mainly in adipose and muscle tissues), which in peripherals begin to break down Tag inside VLDL into FA and MAG (similar to chylomicrons) Æ VLDL is thus reduced to IDL - CETP (cholesterol ester transport protein) – ensures the exchange between HDL to VLDL o CE is transferred from HDL to VLDL o Tag is transferred form VLDL to HDL o This mechanism helps to efficiently transport lipids across the body

Answer 47

- Rise from VLDL by endothelial LPL activities - They differ from VLDL in higher CE content and lower TAG content - Circulation of IDL through the blood is terminated in the liver where they are: a) absorbed and degraded b) HRHL (heparin releasing hepatic lipase) cleaves TAG from IDFL and gets converted to LDL protein

Answer 48

- Most of these are derived from HRHL’s activities, the rest is synthesized de novo - In their core they contain mainly CE, which they transport into tissues - LDL is referred to as ͞bad͟ cholesterol because its acts as atherogenic - At low cholesterol, body cells express the LDL ʹ receptor (for Apo B100 and Apo E) and trap LDL particles - Plasma concentration should be below 3,0 mM, in diabetics below 2,5 mM

Answer 49

Their main role is to transport cholesterol from peripheral tissues to the liver where it can be converted to bile acids and excreted with the feces outside the body - HDL particles are synthesized in the form of flat empty disks (like an empty balloon) in the liver and enterocytes o After synthesis only have Apo AI, AII and AIII and a small amount of Apo C-II and Apo E on its membrane o these blank disks are referred to as nascent ;just emerging or ͞coming to existenceͿ HDL - action of the enzyme LCAT (lecithin cholesterol acyltransferase, cofactor Apo A-I), which esterified cholesterol when transferred to HDL, nascent HDL gradually fills with cholesterol esters and is converted to HDL3 and HDL2α o the difference between HDL3 and HDLϮα is the cholesterol conetnt - HDL3 has less cholesterol - CETP activity brings TAG into both types of HDL o HDL2α will become HDL2β after the addition of Tag, which travels to the liver where it is treated in the same way as IDL o Part of HDL2β disappears in the liver ( and its cholesterols are excreted in the faeces) and part is processed by the enzyme HRHL o If HRHL hydrolyses TAG inside HRHL HDLϮβ͕ then HDLϮβ becomes HDL3 and goes back into blood - HDL is referred to as ͞good͟ cholesterol because it counteracts atherogenesis - Its plasma concentration should be higher than 1.0mM in men and higher than 1,2mM in women - Note: before menopauses women are protected from atherosclerosis by female sex hormones

Answer 50

- Mutation of gene for LDL receptor - Result - bad capture of LDL particles Æ increases levels of cholesterol in blood - Excess cholesterol gets stored in the walls of vessels and causes the development of atherosclerosis and then further complication (myocardial infarction or stroke) at a young age

Answer 51

Ligand for LDL receptor Activator of LPL

Answer 52

o nerve ʹ uses neurotransmitters, a short signal distance o endocrine ʹ uses hormones, long distance signal o immune ʹ uses cytokines, acts in the close vicinity - individual systems are very closely interconnected, no system can be said to be superior or inferior o they work together through individual signaling molecules ʹ some molecules fall into multiple systems example adrenalin = neurotransmitter and hormone - signalling molecules have different effect on adult human and different on growing fetus in uterus (e.g. retinoids ʹ derivatives of Vit.A)

Answer 53

signalling can be divided according to: distance signal travels; receptor location; specificity - autocrine ʹ cell influences itself by feedback - juxtacrine ʹ cell has signalling molecule integrated on its surface and influences the target cells by direct contact - paracrine ʹcell produces a signal to the extracellular matrix and thus affects neighbouring cells - endocrine ʹ cell produces a signalling molecules which goes to the blood by which the signal is transmitted to the target cells - neurocrine ʹ signalling molecule reached the target cell via an axon - pheromone ʹ it has not been directly demonstrated that it works in humans

Answer 54

- serves to control the production of signalling molecules ʹ a certain concentration of signalling molecules stops their further production - negative feedback ʹ control of signalling molecules production (e.g. growth hormones) o concentration-dependent ʹ up to a certain concentration leads to receptor binding and cell response - positive regulation is quite rare in human͛s cell except for tumour cells ʹ they are positively regulated and therefore multiply

Answer 55

- the signal molecule is membrane-bound ʹ two cell contact is required (= signaling by touch) - occurrence o Notch signaling during the development ʹ cells prevents the differentiation of surrounding cells In this way, neurons prevent neighboring stem cells from differentiating into other neurons o In the immune system ʹ e.g. In the induction of apoptosis (FAS a FAS ligand) o nexs ʹ channel in cell membranes connecting their cytoplasms

Answer 56

- cells produce signalling molecules that affect cells in their close vicinity o signalling molecule travels through tissue fluid - occurrence o interaction of neighbouring cells ʹ e.g. during development (growth factors, morphogens) o immune system ʹ uses special signalling molecules, called cytokines o synchronization of GIT function ʹ the so called diffuse neuroendocrine system (DNES) ʹ more about this later .

Answer 57

- hormones (products of endocrine glands) are excreted into blood or tissue fluid o affect organs and tissues that are distance from their place of production o kidney, adrenal gland, thyroid, parathyroid, testes, ovary, placenta

Answer 58

Neurocrine signaling - is used in neuronal communication in nerve tissue - neuron - body (soma, perikaryon) and processes (dendrites and axons) o via axon the signal is in the form of an action potential o myelin sheath allows the signal propagation ;signal ͞jumps͟Ϳ --> faster propagation depolarization occurs only in nodes of Ranvier - neuronal transport ʹ neurotransmitters come out of the end of the axon into the synaptic cleft o in some cases, able to secrete hormones into blood o combination of endocrine and neurocrine signalling - hypothalamic-pituitary system (statins and liberins) oxytocin - effect smooth muscle, take part in milk secretion vasopressin ʹ contraction of muscle in blood vessels, pressure increases, effects renal water resorption

Answer 59

- specific intercellular contact, which is always realized between the signaling cell axon and some other cell, which may be another neuron (information transfer), muscle cell (induce contract), glands (induce secretion) o in the opposite direction, the neuron receives information about what is happening ʹ pain, injury - consists of presynaptic membrane (with neurotransmitter), synaptic cleft, postsynaptic membrane (receptor) - one nerve cell may have up to a thousand of synapses ʹ it is formed mainly in childhood (around 20 years of age, synapses are reduced, which are not used)

Answer 60

- neurotubules (microtubules) + kinesin + cargo (vesicles with neurotransmitter or hormone) o microtubules are shorter than axons ʹ when the vesicle reaches the end of the microtubule, it falls down and must find a new path (microtubule) - Herring body - extension on axon, accumulation of vesicles with hormone throughout an axon - Hypothalamic-pituitary system o Divided into neurophysis (nerve tissue) and adenohypophysis (epithelium) o Neurophysis ʹ non myelinated axons, glial cells (pituicytes), blood vessel

Answer 61

o Affect the rate at which substances are released from a cell or enter the cell o Stimulate the synthesis of proteins or other substances o Activate or supress the activity of already existing enzymes in the target cell - Polypeptide hormones and catecholamines need a receptor on the membrane - Steroids and thyroxine are free to cross the plasma membrane and therefore have a receptor in the cytoplasm - Hormones play a role in maintaining all aspects of homeostasis and some of the (catecholamines) are excreted in the nervous system

Answer 62

- Have a light cytoplasm, a large light nucleus (light because the DNA is in euchromatin form), cristae mitochondria, RER, GA and contain secretory granules full of hormones on the basal side of the cell (close to capillaries which they are in contact with) - Examples of such cells are those that are part of islet of Langerhans o demonstration - immunohistochemistry (using marked antibodies) o among cells is paracrine regulation via somatostatin D cells - somatostatin ʹ supress the secretion of other hormones of islets of Langerhans (insulin and glucagon) and secretion of digestive enzymes in exocrine pancreas and GIT - insulin ʹ insulin secretion is stimulated in B cells by glucose entering the cell into cell o synthesis - nucleus -> mRNA -> GER -> preproinsulin (signalling sequence + c peptide) -> proinsulin (c peptide) -> insulin o transporter GLUT 2 allows the secretion of insulin from cell o effect of insulin of the periphery ʹ binding on insulin onto its receptor which activates the receptor and causes translocation GLUT 4 transporters come from the GA to membrane, allowing glucose to enter the cell

Answer 63

- adrenal medulla ʹ cells arranged in trabeculae - DNES (diffuse neuroendocrine system) ʹ produces serotonin

Answer 64

- Contain SER, tubular MIT and lipid droplets - Adrenal cortex ʹ cells again form trabeculae - hormones ʹ glucocorticoids, mineralocorticoids and sex hormones o ovarium ʹ sex hormones are synthesized In follicles, theca interna cells and yellow body o testes ʹ testosterone is produced by Leydig cells

Answer 65

- retina ʹ reacts to light ʹ cardiac clock ʹ cyclic changes in gene expression o affects the production of melatonin in the pineal gland, GnRH, FSH, LH, estrogens and progesterone

Answer 66

- Influenced by FSH ʹ its binding to the receptor in the primary and secondary follicles initiates the synthesis of estrogen (estradiol) - progesterone is synthesized as an estrogen precursor

Answer 67

- thyroglobulin and enzymes are synthesized in RER and GA and subsequently secreted into the lumen of follicles - iodine pump pumps iodide from blood to colloid 9actve transport) - colloid activates iodine and iodine binds to thyroglobulin = a storage form of thyroid hormones is formed a so called: iodothyroglobulin - after signal binding (TSH) iodothyroglobulin is phagocytosed and in the lysosome is cut into the final hormone, which is subsequently released into blood

Answer 68

Steroid hormones: Gestagens (progesterone), androgens (testosterone), estrogens (estradiol), glucocorticoids (cortisol) and mineralocorticoids (aldosterone) - Steroid signaling molecules are synthesized from cholesterol o The initial and final phases of their synthesis take place in SER, the rest in the matrix of mitochondria o Formed for example in the adrenal gland and gonads - They are synthesized when stimulated by something ʹ the cells do not produce ready-made steroids - Are hydrophobic ʹ in plasma they bind to transport proteins such as SHBG, CBG or albumin - Steroid hormones pass freely through the cytoplasmic membrane and receptors are located in the cytoplasmic membrane o Thyroid hormones have receptors inside the nucleus o Hormone receptor complex binds to DNA and initiates transcription

Answer 69

- Substrate - cholesterol o Two sources - plasma (LDL particles, larger part) and sympathize de novo (smaller part) - transfer of cholesterol from the blood to cell is ensured by the LDL receptor - transfer of cholesterol from cytoplasm to MIT is an ACTH-dependent steroidogenic acute regulatory proteins, which is also a regulatory step of the whole synthesis - cholesterol (27C) -> pregnenolone (21C) -> progestagens (21C) in MIT matrix o this is ensured by cytochrome P450 side chain cleavage enzyme (P450scc) - cleaves side chain - from progestogens, the synthesis of different hormones begins to proceed differently 1) glucocorticoids (21C) 2) mineralocorticoids (21C) 3) androgens (19C) --> estrogens (18C)

Answer 70

- most of the enzymes in these reactions are hydroxylases - progesterone ʹ directly from pregnenolone (it is only dehydrogenation on the 3rd carbon) - cortisol ʹ from progesterone by triple hydroxylation to C11, C17 and C21 o enzymes - hydroxylases o oxygen and NADPH are needed - aldosterone ʹ from progesterone by double hydroxylation on C11 and C21 and subsequent oxidation on C18 o enzymes- hydroxylases aldosterone synthase

Answer 71

- testosterone ʹ from progesterone, when shortened by 2C and keto group is formed on C17, which is subsequently reduced - estradiol ʹ is formed directly from testosterone by the enzyme aromatase, which cleaves one carbon and gives the first ring aromatic character

Answer 72

there are three estrogens - estradiol = before menopause, estriol= in pregnancy, estrone = after menopause o estradiol ʹ main estrogen that ensure changes during puberty and serves to maintain a sex life o estriol ʹ produced mainly by the placenta (its decrease is a sign of fetal developmental disorder) o estrone ʹ arises in peripheral tissues by conversion of androstenedione, which is produced in the adrenal glands ;in menopause there is a decrease in ovarian function͕ so that it is ͞replaced͟ by the adrenal glandsͿ

Answer 73

1) release of cholesterol from internalized LDL 2) StAR protein ʹ cholesterol transporter through the inner MIT membrane 3) MIT side chain cleavage enzyme (depending on where it is, different hormones are produced: testes Ætestosterone, ..) - signal ʹ pituitary hormones (ACTH, LH a FSH) or angiotensin II

Answer 74

- steroid core can not be split! - Steroids cannot be destroyed and are non-polar, so we cannot even get rid of them with urine ʹ That is why the liver had to transform them o We get rid of them similarly to xenobiotics = we change their structure to become polar substances, so they will not be retained in the body and excreted with urine - Small part is excreted unchanged in urine - UFC (urinary free cortisol)

Answer 75

- Its active form is calcitriol - It is not a true steroid but has a similar mechanism of action – intracellular receptor and gene expression regulation - although vitamin D can be produced from cholesterol after sun expose, it is considered a vitamin and therefore is essential in our diet - Affects the body’s calcium and phosphate levels ʹ in medicine it is used to prevent bone diseases - Its precursor is 7-dehydrocholesterol -> sun light cleaves one of its rings -> precalciferol -> cholecalciferol (inactive vitamin D3) -> hydroxylation in liver and kidney -> calcitriol

Answer 76

- Nitric oxide is cleaved from arginine with the participation of the enzyme NO synthase, oxygen and NADPH - There are several types of NO synthases, each occurring in different tissues o NO synthase I ʹ in neurons, where NO acts as a neurotransmitter o NO synthase II ʹ in macrophages where NO helps kill bacteria o NO synthase III ʹ in the endothelium, where NO participates in the regulation of blood pressure ( it can expand blood vessels and thus reduce pressure)

Answer 77

- Synthesis requires trace element ʹ iodine o Iodine deficiency in childhood = hypothyroidism (thyroid hormone deficiency) o Iodine deficiency in childhood = cretinism o Iodine is abundant in the sea, but there is very little in soil ʹ so it is now artificially added into table salt to prevent hypothyroidism and cretinism - Synthesis takes place on a large precursor molecule – thyroglobulin - hormones are stored in the extracellular reservoir (colloid) - in peripheral tissues, T4 is often converted to T3 because T3 is much stronger

Answer 78

1) synthesis of thyroglobulin into ER and GA and its subsequent excretion into the colloid 2) synthesis of enzymes and their transfer to colloid 3) secondary active iodide transport to the cell and then to the colloid 4) oxidation of iodides and iodination of tyrosine residues of thyroglobulin 5) joining of iodinated tyrosine residues in thyroglobulin Æ hormone formation 6) endocytosis and decomposition of thyroglobulin in lysosomes 7) releasing T3 and T4 into blood o if there is insufficient iodine in diet, T3 will be more likely to occur, while as during high levels T4 will be more likely to occur.

Answer 79

Deiodase removes I ʹ from inactive MIT and DIT, thereby recycling them - Transport proteins in blood - TBG (thyroxine-binding globulin), albumin - Peripheral deiodinase in target tissues selectively removes iodine from position 5’ to T4, resulting in more effective T3 o T4 is essentially a prohormone with intrinsic activity - Thyroid disorders are the most common endocrine disease, far more common than diabetes for example o Hypothyroidism – metabolism slows down = patients get colder, they will want heat, they can gain weight o hyperthyroidism ʹ metabolism speeds up = body temperature increases, loses weight

Answer 80

- peptide hormones are hydrophilic and thus freely soluble in plasma - affects cells by binding to the receptor on their surface ʹ after binding activates the membrane enzyme or G protein - neurotransmitters and neuromodulators - neuropeptides, opioids, - hypothalamic releasing hormones and pituitary peptides - somatoliberin, somatostatin, ACTH - hormones of energy metabolism ʹ insulin and glucagon - growth factors - IGF, CSF, EPO - GIT hormones - gastrin

Answer 81

- Synthesis proceeds in the same way as any other peptide for export 1) hormone gene transcription -> 2) translation -> 3) transport to ER -> 4) signal sequence cleavage -> 5) posttranslational modification in GA and eventually cleavage o proinsulin -> insulin o POMC (proopiomelanocortin) -> beta-endorphin, MSH and ACTH - Finished hormones are most commonly stored in GA granules until a signal for their secretion is received

Answer 82

- Constitutive secretion ʹ secretion is continuous and only a small amount is stored in secretory vesicles o Plasma proteins, clotting factors - Regulated secretion ʹ secretion takes place only in response to signal and a certain amount of substances is stored in the secretory vesicles in cell (secretion from cell is after signal Æ e.g via an increase in calcium ion levels in cell) o Cytokines, neuropeptides,

Answer 83

-diffusion of gas molecules -- Diffusion of hydrophobic molecules ʹ bind to intracellular receptor (e.g steroid hormones) - Interaction of signalling molecule with membrane receptor

Answer 84

- Nitric oxide (NO) ʹ produced by the deamination of arginine (enzyme NO synthase) o After its synthesis it travels from the cell directly into the target cell o In target cells activate the appropriate enzyme (guanylate cyclase), which takes care of the rest o Results in smooth muscle relaxation - Carbon monoxide (CO) ʹ works similarly to NO

Answer 85

Hydrophobic molecules like steroid hormones, thyroid hormones, retinoids, or vitamin D, can freely diffuse into cell through the plasma membrane ʹ thus they don͛t need a membrane receptor, only an intracellular receptor - Mechanism of hydrophobic molecules is usually ʹ entry to cell--- intracellular receptor binding--- hormone-receptor complex formation--- binding to DNA--- influencing DNA expression

Answer 86

Interaction with membrane receptor -> receptor produced intracellular signal - Association constant - the higher it is, the better the signaling molecules bind to the receptor - binding of signaling molecule to membrane receptor causes a conformational change in the receptor

Answer 87

- they are large proteins that cross through the cytoplasmic membrane - have 3 parts (domains) ʹ extracellular, transmembrane and cytoplasmic - have characteristic structural domains o extracellular ʹ e.g. immunoglobulin-like domain o intracellular ʹ e.g. protein kinase or death domain

Answer 88

ʹ as the word suggests ʹ it desensitizes the receptor o receptor stops reacting to a signal Æ the same concentration causes a lower effect o long lasting signal = lowers the receptor association constant

Answer 89

ʹ degradation of receptors after signal molecule binding o after binding of the signal molecule, the receptor complex is internalized (receptor-mediated endocytosis), and the molecule falls off the receptor and returns the receptor back to the plasma membrane o signaling molecule travels to the lysosome where it is destroyed o but some part of the receptor travels to the lysosome, along with the signaling molecule, where it is also destroyed o long-lasting signal = lowers the number of receptors

Answer 90

- ion channel linked receptor ʹ ligand-gated ion channels - G protein-linked receptors - Protein kinase-linked receptors - Death domain-linked receptors - Receptors regulating proteolysis

Answer 91

- These receptors use synaptic and intracellular signaling (e.g. Ca2+ release from SER during muscle contraction) - Causes a change in membrane potential, causing further changes in the cell - The main type of receptors in nerve tissue

Answer 92

- Have a specific structure - have 7 transmembrane regions - G protein - 3 subunits - α ;alfa͕ largest, carrying GDP or GTP), β ;beta and γ ;gamma o function ʹ activation of enzyme after signal from receptor - example ʹ hormone receptor binding -> receptor activation -> G protein attachment -> disconnection of GDP -> GTP binding -> detaching of G protein from receptor -> disconnection of α; with GTP from β and γ -> binding of α (with GTP) to the enzyme -> enzyme activation - after some time, GTP becomes GDP ʹ at that moment α binds the enzyme and reconnects with β and γ

Answer 93

- two types ʹ receptor kinases (with intrinsic kinase activity) and receptors associated with kinases - receptors kinases ʹ intracellular domains of these receptors have kinase activity (they can phosphorylate) o two types of receptor kinases o receptor tyrosine kinases ʹ receptor for everything except TGF-β (e.g. EGF, insulin, IGF-I, NFG, PDGF...Ϳ o receptor serine-threonine kinases - receptors for TGF-β - Protein kinase-associated receptors - individual kinases are attached to the intracellular domains of these receptors o Two types of receptors associated with protein kinases o Jak kinase and Src kinase o examples of receptor ligands associated with protein kinases ʹ growth hormone, erythropoietin, interferons

Answer 94

- the death domain is the intracellular part o the final effect of their signalling pathways is apoptosis ʹ activation of the death domain receptor kills the cell - adapter proteins - e.g TRADD or FADD - examples of ligands that bind to death domain receptors ʹFas ligand, TNF - this type of signalling is used, for example by NK cells to kill tumour cells and virus-infected cell

Answer 95

- the ligand binding receptor through the appropriate proteins regulates proteolysis of a particular protein by phosphorylation and subsequent ubiquitination - examples of ligand regulating proteolysis - IL-1

Answer 96

- Molecules that diffuse into the cell ʹ like gas molecules and hydrophobic molecules - Types of molecules mediating intracellular signaling after the interaction of extracellular signaling molecules with receptor: o Ions͕ small organic molecules;͞second messengers ͞Ϳ͕ GTP binding proteins, protein kinases, other proteins

Answer 97

- After diffusion of NO into the smooth muscle cells, guanylate cyclase is activated - Activated guanylate cyclase converts GTP to cGMP - cGMP activates protein kinase G (PKG) - PKG inhibits the actin-myosin -> vasodilatation

Answer 98

- After diffusion of a hydrophobic signaling molecule, binds to the intracellular receptor and forms a molecule-receptor complex - The molecule-receptor complex goes to the nucleus, where it binds to DNA and directly affects transcription

Answer 99

- Signalling via ligand-regulated ion channels - Change of intracellular Na+ /K+ -> change of cell membrane potential o Change of membrane potential in neurons is of special importance ʹ it can cause action potential (excitement) - Change in cytosolic Ca2+ levels- as part of IP3/DAG signalling pathway o After the release from ER through ion channels in the ER membrane o Ca2+ pumps are responsible for maintaining low cytosolic Ca2+ levels o Calmodulin ʹ protein that binds Ca2+

Answer 100

- small organic molecules that mediate intracellular signalling o some textbooks treat all IC molecules as secondary messengers - are involved in signalling through receptors associated with the G protein - types of second messengers o inositol triphosphate (IP3) o diacylglycerol (DAG) o cyclic adenosine monophosphate (cAMP) o cyclic guanosine monophosphate (cGMP) - G protein ʹ provides signal transmission from the receptor to the intracellular effecter molecule o There is a stimulatory G protein (Gs) and an inhibitory G protein (Gi) o signalling depends on the what effector molecules G protein activates phospholipase C (PLC) ʹ breaks down the phospholipid PIP2 to IP3 and DAG adenylate cyclase - converts ATP to cAMP cGMP phosphodiesterase ʹ breaks the bond between phosphate and 3rd carbon in cGMP---GMP is formed guanylate cyclase - converts GTP to cGMP

Answer 101

- GTP binding proteins have bound GTP (and are active) or GDP (and are inactive) - GTP binding protein is G protein or Ras protein (which plays a role in signaling from receptor tyrosine kinases)

Answer 102

- Protein kinases are enzymes that phosphorylate certain proteins - E.g. tyrosine kinases and serine-threonine kinases - Types of protein kinases in intracellular signalling o Receptor-associated protein kinases Src kinase and JAK kinase - STAT signalization o Protein kinases of intracellular signalling cascades Raf kinases and MAPKK - MAPK signalling cascade PI3 kinase ʹ signalling from receptor tyrosine kinases o Terminal protein kinases ʹ are at the end of the signalling cascade, they are already realizing the signal PKC, CAMK, PKA, MAPK, PKB;Akt and IKb kinase

Answer 103

- They are mostly adapter proteins and enzymes with a different function than protein kinases - Adapter proteins ʹ e.g Grb2 and Sos ʹ proteins associated with receptor tyrosine and receptors with death domains - enzymes ʹ e.g. enzymes activated by G protein - PLC, adenylate cyclase, cGMP phosphodiesterase o caspases activated through death domain receptors

Answer 104

- regulation of membrane potential – by ligand-regulated ion channels - regulation of the expression of the respective proteins ʹ either by nuclear receptors or by activation of transcription factors - regulation of the activity of respective proteins mostly regulation of the activity based on phosphorylation

Answer 105

- can be opened by both extracellular ligands and intracellular - their opening leads to the passage of ions, which changes the membrane potential and transforms the chemical signal into an electrical one - application of ligand-regulated ion channels o in synaptic signaling ʹ membrane depolarization is essential for neurons and conduction o in photoreceptor signaling in rods ʹ in the darkness, there is a lot of cGMP in the cytoplasm in the retina cells that keeps certain ion channels permanently open the effect of light on the cell activates opsin, which is a membrane receptor associated with the G protein ʹ G protein activates cGMP phosphodiesterase, which immediately decomposes cGMP in the cytosol. once cGMP levels fall, the ion channels are closed and cell hyperpolarization occurs

Answer 106

- they are intracellular receptors of extracellular hydrophobic molecules - function ʹ ligand binding to the receptor forms a complex that translocates to the nucleus and affects gene expression - nuclear steroid hormone receptors are homodimers

Answer 107

- is realized by terminal protein kinases - membrane-associated kinases are always tyrosine kinases - kinases in the cytosol are always serine-threonine kinases o only exception is the TGF-β ʹ receptor - this is a serine-threonine kinase in the membrane

Answer 108

- in NO signaling - there is cGMP in cell -> PKG activation -> inhibition of actin-myosin complex -> relaxation of vascular smooth muscles---- vasodilation

Answer 109

- in IP3/DAG signalling - there is DAG and Ca2+ in the cell -> PKC activation-> phosphorylation of different proteins in different cell types

Answer 110

- in Ca2+ signaling - release of Ca2+ from ER -> binding to calmodulin Æ complex Ca2+-calmodulin activates CAMK -> phosphorylation of transcription factors Æ regulation of expression of relevant genes

Answer 111

- in cAMP signaling - there is cAMP in the cell -> PKA activation -> phosphorylation of transcription factors and other target proteins - phosphorylates example glycogen phosphorylase (an enzyme of glycogenosis) and CREB (transcription factor)

Answer 112

- in Ras/MAPK signaling - active MAPKK -> activation of MAPK -> phosphorylation of transcription factors Æ expression of relevant genes

Answer 113

- in PI3/Akt signalling - active PI3 kinase -> PKB activation -> Bad protein phosphorylation -> Bad protein binding by 14-3-3 -> inhibition of apoptosis - free Bad protein blocks the anti apoptotic protein, triggering apoptosis

Answer 114

- in Smad signaling - ligand linked activation of dimer-- activation of receptor cytoplasmic domain (phosphorylation) Æ phosphorylation of Smad2/Smad3 -> oligomerization with Smad 4 (transcription factor) -> regulation of gene expression

Answer 115

- in STAT signaling - dimerization of receptor after ligand interaction--- mutual phosphorylation and activation of JAK kinases--- phosphorylation and activation of cytoplasmic domains of receptor--- binding and phosphorylation of STAT proteins--- dimerization of STAT proteins (transcription factor)-- regulation of transcription of relevant genes

Answer 116

- in NFκB signaling - receptor oligomerization after ligand interaction-- binding of other proteins--- phosphorylation and activation of IkB (inhibitor of kappa B) -> ubiquitination and subsequent degradation of IkB -> release of NFkB ;transcription factor) -> regulation of gene expression

Answer 117

- in WNT signaling - receptor interaction (Frizzled) with ligand (Wnt = Wingless) -> activation of Dishevelled protein Æ binding and activation of CK1, GSK3, axin, and APC complex Æ prevention of B-catenin phosphorylation (transcription factor) catenin Æ stable ɴ-catenin -> regulation of gene expression

Answer 118

- Signalling pathways ʹ signal transmission from the primary signal (signalling molecule) to its realization in the cell (physiological responses) o Interconnection of signalling paths = signalling network - The same signalling molecule elicits different responses in different cell types

Answer 119

- Nitric oxide (NO) is produced in the body by deamination from arginine (arginine---- citrulline + NO; by the enzyme NO- synthase) - Signalling pathways - NO -> diffusion into smooth muscle cells around blood vessels -> activation of guanylate cyclase - > production of cGMP -> PKG activation -> inhibition of actin-myosin -> muscle cell relaxation -> vasodilation - function ʹ regulation of vasodilation - regulation increases- nitroglycerin (provides more NO) o lowers - cGMP phosphodiesterase inhibitors (viagra) - NO is also used in immunity ʹ activated macrophages synthesize NO in the fight against microorganisms

Answer 120

- steroid hormones ʹ cortisol, aldosterone, testosterone, estradiol, progesterone - thyroid hormones - thyroxine (T4) - retinoids ʹ retinoid acid (vit. A) - vitamin D - vitamin D3 - example of signaling ʹ stimulation of gluconeogenesis by cortisol o cortisol -> diffusion to liver cells -> binding to intracellular receptor -> translocation of cortisol receptor complex to the nucleus --binding to the regulatory gene region of gluconeogenesis -> expression of genes -> gluconeogenesis

Answer 121

o Glucocorticoids - cortisol stimulates gluconeogenesis o mineralocorticoids ʹ aldosterone regulates ion levels

Answer 122

o testosterone ʹ stimulates spermatogenesis, ensures development of secondary sexual characteristics, promotes anabolism o estradiol ʹ controls the menstrual cycle and ensures the development of secondary sexual characteristics o progesterone ʹ helps implant the fertilized egg in the uterus

Answer 123

o Thyroxine (T4) and triiodothyronine (T3) ʹ metabolic regulation

Answer 124

o Retinoic acid ʹ functions as a morphogen = signaling molecule used in fetal uterus development Disbalances of morphogens leads to various congenital developmental defects

Answer 125

- Signal transmission between two neurons or between a neuron and another target cell (e.g. muscle) - It is mediated by neurotransmitters, which are amino acids, amines͕ and esters͙ o Neurotransmitters can be both excitatory and inhibitory

Answer 126

o acetylcholine ʹ choline derivative, a neurotransmitter of the neuromuscular junction o GABA - gamma-aminobutyric acid, glutamate derivative, major inhibitory NT in CNS o dopamine ʹ tyrosine derivative, belongs to catecholamines o serotonin ʹ tryptophan derivate - signaling examples ʹ signal transmission between two neurons by acetylcholine o acetylcholine -> opening of Na+ /K+ channels in plasma membrane -> entry of Na+ into cell -> change in membrane potential (depolarization) Æ electrical signal

Answer 127

- signaling through G protein ʹcoupled receptors - activated phospholipase C (PLC) catalyzes the reaction of PIP2 -> IP3 + DAG o PIP2 - phosphatidylinositol-4,5-bisphosphate o IP3 – inositol triphosphate ʹ serves as a ligand for a ligand-regulated ion channel that releases Ca2+ from ER o DAG - diacylglycerol ʹ activates protein kinase C (PKC)

Answer 128

- Ca2+ dependent serine-threonine kinase o Realizes a signal based on phosphorylation of target proteins - Examples of signalling IP3/DAG ʹ stimulation of platelet aggregation by thrombin o thrombin -> activation of membrane receptor-- activation of G protein-- activation of PLC -> degradation of PIP2 DAG -> PKC activation IP3 -> Ca2+ release from ER o Ca2+ + active PKC = functional PKC -> protein phosphorylation--- platelet granule release-- aggregation - Other PKC target proteins o Membrane receptors ʹ desensitization of EGF receptor, activation of Ca2+ ATPase o Signalling pathways kinases ʹ activation of Raf kinase (connection of Ras.MAPK signalling pathway ) - Other examples of IP3/DAG signalling pathways o acetylcholine ʹ contraction of smooth muscle cells o vasopressin ʹ glycogenolysis in hepatocytes

Answer 129

- Partially linked to IP3/DAG signalling (IP3 acts as a ligand for Ca2+ ion channels) - After the release of Ca2+ from ER, calmodulin protein starts to take up free protein Ca2+ in the cytoplasm o Calmodulin is a dimer and each of its subunits has 2 free spots for calcium, therefore, the whole calmodulin will receive 4 Ca2+ - Calcium-saturated calmodulin activates Ca2+-dependent kinase (CAMK) - CAMK ʹ realizes signals based on the phosphorylation of target proteins - Pathway examples - Ca2+ -> binding to calmodulin -> CAMK activation -> phosphorylation of CREB protein (transcription factor) -> binding to the CRE region in the regulatory section of target genes-- transcription--- physiological response - Regulation of Ca2+ signaling - Ca2+ ionophores (ionophore is a substance enabling ion transfer through lipid barrier)

Answer 130

- Signalling from G protein ʹcoupled receptors-- activation of adenylate cyclase - Activated adenylate cyclase catalyses the reaction of ATP--- cAMP - cAMP ʹ activates protein kinase A (PKA), a serine-threonine kinase that realizes a signal based on the phosphorylation of target proteins - cAMP phosphodiesterase ʹ catalyses the reaction of cAMP--- AMP - examples of cAMP signalling ʹ stimulation of glycogenolysis by glucagon in the liver o glucagon -> membrane receptor activation -> G protein activation -> adenylate cyclase activation -> cAMP production -> PKA activation -> glycogen phosphorylase activation ---glycogenolysis - PKA target proteins o Glycogen phosphorylase ʹ induction of glycogenolysis o CREB protein - cAMP response element binding, transcription factor binding to the CRE region in the regulatory section of genes - Other examples of cAMP signalling o adrenalin ʹ an increase in the frequency of heart contractions o TSH ʹ thyroxine secretion for the thyroid gland - Regulation of cAMP signalling ʹ cholera toxin, phosphodiesterase inhibitors (caffeine)

Answer 131

- Mechanism of converting a light signal into electrical in rods of the retina - cGMP ʹ opens ligand-regulated ion channels in the membrane o in the dark, there are many in the cell- channels are open = no hyperpolarization - photoreceptor signalling ʹ light radiation ʹ light radiation -> rhodopsin activation -> G protein activation-> cGMP phosphodiesterase activation -> cGMP degradation -> ion channel closure -> membrane hyperpolarization -> electrical signal

Answer 132

- signalling of most classical growth factors (except TGF-β via receptor tyrosine kinases) o EGF, FGF-1, FGF-2, HGF, IGF-I, IGF-II, NGF, PDGF - Signalling example - EGF -> activation of membrane receptor -> activation of GRB2 and SOS -> activation of Ras -> activation of Raf -> activation of MAPKK -> activation of MAPK -> activation of transcription factors -- proliferation - The whole signalling is complicated because the molecules have other names o Raf = MAPKKK, MEK = MAPKK, ERK = MAPK o Raf is a non-receptor serine ʹthreonine kinase - Ras/MAPK function is mostly a regulation of proliferation in different cells - Other examples of Ras/MAPK signalling o insulin ʹ regulation of metabolism in many cell types o EGF ʹ stimulation of proliferation in epithelial cells o HGF ʹ stimulation of proliferation in hepatocytes - regulation of Ras/MAPK signalling ʹ since cells use this pathway to promote proliferation, in pharmacology it is targeted to treat tumours (as an inhibitor)

Answer 133

- TGF-β signalling via receptor serine-threonine kinase - Example of signalling ʹ inhibition of proliferation by TGF- β o TGF- β ->activation of membrane receptor -> activation of Smad2/Smad3 protein -> oligomerization of Smad2/Smad3 a Smad4 (transcription factor is formed) -> oligomer binding to the regulatory region of the p15 gene -> transcription -> p15 protein expression -> inhibition of cell cycle progression -> inhibition of proliferation - Smad signalling often inhibits proliferation in different cell types - Smad signalling activated is regulated by TGF-β receptor inhibitors

Answer 134

- Signalling of most cytokines regulating cells of haemopoietic origin via receptors associated with Jak kinases - Ligands of receptors associated with Jak kinases IL-2, IL-6, IFN-gamma, erythropoietin (EPO), growth hormone - Example of signalling ʹ stimulation of erythrocyte proliferation and differentiation by erythropoietin o Erythropoietin -> membrane receptor dimerization -> mutual activation (phosphorylation) Jak kinase -> membrane receptor activation (phosphorylation)--- phosphorylation and dimerization of STAT proteins (transcription factor formation)--- binding to Bcl-xL gene region---transcription-- protein Bcl-xL ---apoptosis inhibition---proliferation and differentiation - Other examples of STAT signalling o IFN-gamma - activation of macrophages o growth hormone ʹ stimulation of IGF-I in liver and other cells - STAT signalling is regulated through Jak kinase inhibitors o There is also a potential use in the treatment of blood cancer

Answer 135

- Death domain receptor ligands - Fas ligand, TNF (tumour necrosis factor) - caspases ʹ proteins involved in the process of apoptosis o activated by proteolytic cleavage - case of death domain receptor signalling ʹ induction of apoptosis of virus-infected cell via Fas ligand anchored to the T cell membrane o Fas ligand -> activation and trimerization of Fas receptors in the infected cell membrane--- binding of procaspase 8 and FADD adapter protein (DISC complex formed) ---activation of caspase 8---activation of caspase 3--proteolytic cleavage of death substrates---realization of apoptosis - Signalling via death domain receptors is used to induce apoptosis o TNF ʹ induction of apoptosis in tumour cells - Regulated by specific caspase inhibitors

Answer 136

- In response to damage and infection - Ligand receptors for NFĸB signalling - IL-1, TNF-α - Example of NFĸB signaling - IL-1 ʹ induction of inflammatory response based on the expression of inflammatory cytokines in T lymphocytes o IL1-1 -> membrane receptor activation -> activation of IĸB kinase -> phosphorylation of IĸB -> ubiquitination of IĸB -> degradation of IĸB -> release of NFĸB (transcription factor) from IĸB binding -> binding to DNA -> transcription -> expression of inflammatory cytokines -> induction of inflammatory response - regulation of NFĸB signalling ʹ NFĸB inhibitors

Answer 137

- Wnt is a signalling molecule - Membrane Wnt receptor = Frizzled - Example of Wnt signalling ʹ regulation brain cell development o Wnt -> activation of Frizzled -> activation of Dishevelled -> inactivation of CK1-GSK3-axin-APC -> prevention of β-catenin phosphorylation -> prevention of β-catenin ubiquitination -> prevention of β-catenin degradation ->binding of β-catenin to DNA -> transcription of relevant genes -> regulation of development - β-catenin is a co-activator of the transcription factor - Wnt signalling function ʹ regulation of ontogenesis, e.g brain o Overexpression in tumour cells - Wnt signalling is regulated by inhibitors of individual members of the signalling pathway, which can potentially be used in tumour therapy

Answer 138

endocrine ʹ hormones (= highly active substances that are produced by endocrine glands and then secreted into the blood, and ultimately to the target cell/tissue/organ where they have a specific effect; they can work at very low concentrations (10-8 - 10-11M) paracrine ʹ cytokines autocrine ʹ cytokines synaptic ʹ neurotransmitters

Answer 139

1. Epiphysis (Pineal gland) 2. Hypophysis (Pituitary gland) 3. Thyroid glands and parathyroid gland 4. Thymus 5. Adrenal glands 6. Ovaries and Testes 7. Pancreas

Answer 140

Thalamus, Hypothalamus, and Epithalamus

Answer 141

o integrating centrum -> its main function is to transfer signals from the lower parts of the nervous system (spinal cord, brainstem, and cerebellum) and basal ganglia to the cortex and striatum

Answer 142

o One of the few parts of the brain in which there is sexual dimorphism o Has very complex functions---basically regulates all-important activities of the body Circadian cycles (e.g sleep -> even longer periods, such as puberty), whose automation is found in the suprachiasmatic nucleus (large number of cells directly behind the eyes) Hormone productionʹ> oxytocin, ADH, statins (somatostatin = GHIH, prolactin inhibiting hormone = dopamine = PIH) and liberins (GRGH, CRH, GnRH, TRH) thermoregulation centers regulating hunger and thirst sexual behavior and probably sexual orientation ͣfight-or-run ͞response sense of pleasure

Answer 143

Posterior segment of the diencephalon. Contains the thalamus, hypothalamus, and pituitary gland

Answer 144

hormone: melatonin o chemical structure: amine o typical effects: involved in biological rhythms (circadian rhythms) o regulation by: light and dark cycles (maximum production at night) Circadian rhythms: o By Earth rotating around its axis, 24 hours a day/night cycles of light and darkness accompanied by the evolution of all life forms o Biologicals cycles: sleep ʹ waking hormonal secretion body temperature and blood pressure motor activity starvation ʹ fullness/satiation Circadian rhythm disorders: o sleep period disorders (genetically determined) advanced sleep phase (19 ʹ 4 o͛clockͿ delayed sleep phase (2 ʹ 11 o͛clock) o Metabolic syndrome (obesity, diabetes mellitus) o Blood pressure (hypotension, hypertension) o Coronary syndrome (myocardial infarction)

Answer 145

Growth Hormone GH ↑ growth + metabolism hypothalamic h. Prolactin PRL ↑milk production + secretion hypothalamic h. Thyroid-stimulating hormone TSH ↑ thyroid gland hypothalamic h. + T4 Adrenocorticotropic hormone ACTH ↑ adrenal cortex → glucocorticoids hypothalamic h. a glucocorticoids Follicle-stimulating hormone FSH ↑ production of ova and sperm hypothalamic h. Luteinizing hormone LH ↑ ovaries and testes hypothalamic h.

Answer 146

insulin-like growth factor, IGF͟-> its production is stimulated by GH and may be limited by e.g. intensity of GH, lack of GH receptors͙ there are generally 3 growth periods in humans: o Infantine ʹ up to 2. Years of age (50 % of final height) axis: glucose – insulin – IGF-I o Children ʹ until the beginning of pubertal development (30 % of height) axis: growth hormone– IGF-I o Pubertal ʹ up to adult height (20 % of height) axis: growth hormone– IGF-I + sex hormones

Answer 147

Growth retardation o Combined deficit of pituitary hormones o Isolated growth hormone deficiency o Insensitivity to growth hormone o Hypothyroidism o Hypercortisolism Cushing’s diseaseʹ damage at the central level, high activity of adenohypophysis leads to overproduction of ACTH and excessive stimulation of the adrenal cortex Cushing’s syndromeʹ excessive activity of the adrenal cortex, adenohypophysis tries to regulate it by decreased ACTH secretion but the adrenal cortex is ͞doing its own thing͟

Answer 148

it has no gland structure, so it cannot synthesize hormones -> it only stores them Antidiuretic hormone ADH ↑ retention of water by kidneys Water/salt balance oxytocin ↑ contraction of uterus + mammary gland cells Nervous system

Answer 149

Diabetes insipidus o it is a disease caused by a lack of ADH / insensitivity of the receptors in the kidney which is manifested by polyuria (no resorption of water in the kidneys = loss of liquids/ increased urine excretion) it also causes decrease in osmolality of urine and increase of osmolality of serum (blood serum = yellowish liquid without cell elements -> formed after blood clotting and subsequent clot removal) o when the Glc high concentration is greater than 10mM, it is excreted in the urine o thirst and associated polydipsia (compensation for dehydration ʹ drinking too much) Diabetes insipidus centralis o ADH-dependent; decrease in ADH) o cause: insufficient secretion of ASH leading to CNS pathology o treatment: ADH is substituted by desmopressin (a synthetically produced substance that is chemically similar to ADH => a specific form of drug that contains desmopressin, eg Minirin => is also used in some forms of nocturnal wetting in children and frequent forced urination at night in adults) Diabetes insipidus renalis o ADH-independent; increase in ADH cause: renal receptor insensitivity - renal tubule disorder -> gene mutation: for ADH receptor for cellular water channel, aquaporin 2 o treatment: Sufficient fluid intake, sodium restriction in the diet, administration of diuretics (drugs that affect membrane transport in the nephron -> inhibit re-absorption of NaCl and water from the tubule)

Answer 150

T4 a T3 amine ↑ metabolism TSH calcitonin peptide ↓ blood calcium level Calcium in blood

Answer 151

Decreased hormone production (increase in TSH a) Congenital hypothyroidism thyroidal dysgenesis: - can be caused by improper gland development => agenesis (congenital malformation of the organ ʹ generally any part of the body) + aplasia (malformation or lack of organ) + hypoplasia (imperfect organ development) - cystic malformation - ectopia (= occurrence outside its usual location) thyroidal dyshormonogenesis: - impairment of any degree of hormone synthesis or secretion b) acquired hypothyroidism it is chronic autoimmune thyroiditis = Hashimoto’s thyroiditis it is the most common cause of hypothyroidism -> relatively common disease affecting up to 5 % of the population with a significant female prevalence (4:1) treatment: hormone replacement Increased hormone production (decrease in TSH) o Autoimmune stimulation of TSH receptor ʹGraves-Basedow thyrotoxicosis The body produces antibodies against TSH receptor -> after hormone binding the receptor is activated which leads to hormone production

Answer 152

parathormone (PTH) peptide ↑ blood calcium level Calcium in blood

Answer 153

Thymosin peptide stimulates T lymphocytes

Answer 154

Adrenal medulla Activates in acute stress adrenalin, noradrenaline amine ↑ blood glucose level ↑ metabolism vessel constriction Nervous system Adrenal cortex Activates under chronic stress glucocorticoids -cortisol (zona fasciculata) ↑ blood glucose level immunosuppression ACTH mineralocorticoids -aldosterone (zona glomerulosa) ↑ reabsorption of Na+ ↑ excretion of K+ in kidneys Kalium in blood

Answer 155

Reduced hormone production (increase in ACTH) o Congenital adrenal hyperplasia (AR hereditary disorder of steroid hormone synthesis) Metabolic disorder with enzymatic block => one of the five necessary enzymes for steroid hormone synthesis is missing, leading to a deficit of a specific steroid group and at the same time an excess of another group due to the over-production of ACTH The most common deficiency is 21-hydroxylase (gene CYP21) -> up to 95 % of cases -Decreased cortisol and aldosterone secretion -salt-wasting -elevated 17-hydroxyprogesterone level o adrenal insufficiency (gland damage) reduced production of cortisol and aldosterone -autoimmune process (Addison’s disease) => formation of antibodies that damage the adrenal cortex damaged adrenal glands can be due to genetics or infection ʹ e.g. meningococcal infection causes both adrenal bleeding and complete destruction, which very often leads to death (*adrenal bleeding = Waterhouse-Friderichsen syndrome) Increased hormone production (decrease in ACTH) o tumours Cushing’s syndrome ; increase in cortisol) - Manifested by obesity (fat mainly in the face and abdomen) increased appetite, the skin is characterized by purple stretch marks, osteoporosis, DM2, depression Conn syndrome ;increase in aldosterone -Aldosterone producing adenoma -Decreased sodium excretion (higher extracellular fluid volume, vascular fluid increase leads to hypertension, which is also associated with headache, fatigue, nasal bleeding which further leads to increased blood pressure and may also cause heart failure), increased potassium excretion (may occur) constipation, muscle weakness, heart rhythm disorders

Answer 156

- Affect genital and secondary sexual characteristics Adrenal cortex - zona reticularis androgens – lead to hair production in men and women ACTH Ovaries - in follicle, corpus luteum estradiol (+progesterone) FSH + LH Testes - in Leydig cells testosterone LH

Answer 157

Reproductive axis: hypothalamus – pituitary – gonads Three periods of reproductive axis activity: o Fetal – maximum at week 20. (1/2) of pregnancy Development of internal and external genitalia o Infant – maximum between 3.-4. month „physiological mini puberty “ development of sexually determined brain o Pubertal and continuing adulthood Development of secondary sexual characteristics (breast in women, genitalia in men, pubic hair in both) the first two periods depend only on androgens (testosterone)

Answer 158

Central premature puberty o increase in sex hormones gonads (testosterone /aldosterone) o gonadotropin-dependent disorder - an increase in FSH and LH secretion is required to start the disorder o causes: hypothalamus, pituitary gland premature activation of the reproduction axis o isosexual: in accordance with biological sex Peripheral premature pseudopuberty o an increase in gonad sex hormones o gonadotropin-independent disorder -decrease in FSH͕ and LH leads to increased sex hormone production without stimulus o cause: gonads, adrenal glands o heterosexual: masculinization of women, feminization of men

Answer 159

- a reproductive disorder The cause is a postzygotic activating mutation of the G protein α-subunit gene -> Activation of hormone-stimulating receptor signal for melanocytes----manifested as characteristic mapped skin lesions (ͣcafé au lait) Activation of the parathyroid hormone (PTH) receptor signal -> bone fibrous dysplasia (spongiosis is replaced by connective tissue - the bones are then easily deformable) Activation of FSH -> pseudopuberty receptor signal in girls, less often in boys *clinical triad = this includes these symptoms => mapped skin lesions, bone fibrous dysplasia, isosexual premature pseudopuberty in women

Answer 160

o Lack of signs of reaching adolescence o More common in boys, is accompanied by a disorder of bone maturation and also a disorder of body growth Hypogonadotropic hypogonadism (central) decrease in gonad sex hormones gonadotropin-dependent ; decrease in FSH͕ LH causes: hypothalamus, pituitary gland Hypergonadotropic hypogonadism (peripheral) decrease in gonad sex hormones gonadotropin-independent increase in FSH͕ and LH) cause: gonads

Answer 161

Langerhans islets ʹ alfa cells produce glucagon /beta produce insulin insulin ↓ blood glucose level Glucose in blood glucagon ↑ blood glucose level Glucose in blood Regulation of Glc levels in blood: o increase: glucagon, adrenaline, cortisol, ACTH, growth hormone, thyroxine o reduce: insulin, somatostatin

Answer 162

Diabetes mellitus o Hyperglycaemia, glycosuria with glycaemia greater than, 10 mmol/l (glc in urine) Diabetes mellitus 1. type o cause: autoimmune destruction of β cells, leading to insulin deficiency o typical occurrence already in childhood (in any case it is no exception that it develops at any time ʹ gradual development) o it is generally a condition in which the blood glucose value is higher than 5,6 mmol ---increased glucose concentration in extracellular fluid leads to an increase in osmolality, osmotic diuresis, polyuria (which leads to dehydration) further manifested by increased ketone formation, acetone odour, lowering of pH---- acidosis (leads to respiratory centre irritation ---Kussmaul breathing) - may result in coma o therapy: insulin substitution Diabetes mellitus Type 2 o It is a metabolic disorder in which glucose cannot be processed due to absolute or relative insulin deficiency and at the same time reduced tissue sensitivity to insulin ( = insulin resistance) Manifested by polyuria, dehydration, thirst, hyperglycaemia, weight loss, fatigue, and vision problems, may also manifest as disorders of consciousness, susceptibility to infections, macrovascular (atherosclerosis...) and microvascular complications (retinopathy, neuropathy.) o cause: metabolic ʹ obesity o therapy: diet + physical activity

Answer 163

- many cells (neurons and glial cells), little intercellular space - function ʹ intake, analysis, integration, and transmission of information; coordination of organism functions - irritability and conductivity ability of the cell to receive physical or chemical irritation and react to it by nerve impulse (excitement), which is evaluated in the cell and eventually forwarded - neurons use both electrical (membrane depolarization) and chemical (synaptic) signaling - transmission of excitement from receptor to effector = reflex

Answer 164

- cell body (perikaryon, soma), dendrites and axon

Answer 165

o it is the trophic center of the neuron - supplies all its processes with the necessary substances o nucleus - large, round, and light (mainly contains euchromatin and noticeably large nucleolus) o Rough ER (in neurons it is called Nissl's substance), polyribosome o GA is only in the perikaryon, there may be several o mitochondria mainly in axonal endings o lipofuscin granules and melanin inclusions

Answer 166

short projection that lead to perikaryon excitement o one neuron has up to hundreds of thousands of contacts o look like branches of a tree crown - they start thick and thick, but gradually branch and thin o branching neurons help increase the reception area (= the area that receives the signal)) o The composition of the cytoplasm of dendrites is the same as in the perikaryon o some intermediate filaments (neurofilament, NF-M, NF-L, NF-H) are typical for dendrites

Answer 167

ʹ conducts excitement from the perikaryon o mostly myelized, different length process containing smooth ER o A neuron usually has only one axon, but it can branch into end-to-end collaterals o axolemma axon membrane conducts nerve impulse o axoplasma - axon cytoplasm, contains many mitochondria, microtubules, and microtubule proteins (MAP1) o do not have a proteosynthetic apparatus - they are fully dependent on perikaryon o initial segment - membrane on the surface of the distance conus, increased amount of ion channels after exceeding the threshold value, an axon signal is sent, until then nothing

Answer 168

vesicles with neurotransmitters (using kinesin) are transported along microtubules it is necessary to maintain a permanent transport between the perikaryon and the axon end - all important structures;organelles͕ proteins are synthesized in the perikaryon and must therefore be transported to the axons worn out substances are transported from the neuronal endings by retrograde transport through axons back to the perikaryon

Answer 169

- always anterograde direction, ie from the first depolarization to the axonal ending - reverse movement (retrograde) is prevented thanks to a special mechanism of closing sodium channels - Nerve impulse is transferred from presynaptic cell at the site of synapse to postsynaptic (effector cell)

Answer 170

- microtubules- axoplasmic transfer from perikarya to synapse, shape regulation - neurofilaments (intermediate filaments) - mechanical stability of the cell - microfilaments- anchoring of membrane structures, stabilization of intercellular junctions, movement of cell processes

Answer 171

- by the number of projections o unipolar- only one protuberance (axon), dendrites are transformed into specialized endings (rod in the retina) o bipolar- one axon and one dendrite, usually on opposite sides of the body also, called sensory neurons - found in olfactory mucosa, retina, and cochlear and vestibular apparatus of the inner ear o pseudounipolar- dendrite and axon merge into one projection, then split again o multipolar- the most common, they have a lot of dendrites and one axon - according to axon length o Golgi type I - long axon neurons o Golgi type II - neurons with short axon - according to the direction of excitement o afferent- they convert information from receptors (PNS) to the CNS o efferent- they convert the excitement from the CNS to the effectors o interneurons- inserted between afferent and efferent neurons

Answer 172

- connection of two neurons - three parts - presynaptic region (axon ending), synaptic cleft and postsynaptic membrane (another neuron) - types- axodendritic (axon- dendrite), axosomatic (axon-soma), axoaxonal (axon-axon)

Answer 173

- the action potential opens the voltage-dependent calcium channels of the presynaptic membrane - increased Ca2+ n the cell leads to exocytosis of synaptic vesicles (containing neurotransmitters) into the synaptic cleft - the neurotransmitter diffuses into the postsynaptic membrane where it interacts with the receptors - the neurotransmitter is then removed from the cleft-cleaved (acetylcholine esterase) or resorbed, either back to the axon where it came from or to astrocytes

Answer 174

there are 10-50 times more than neurons, but they are smaller, making up about half of the CNS volume - functions - create myelin, nourish neurons, phagocytize what is needed, and generally form a support network for neurons

Answer 175

- central glia - astrocytes, oligodendrocytes, microglia, ependym - peripheral glia - satellite cells, Schwann cells

Answer 176

- function o Isolation barrier - they are part of the blood-brain barrier o Nutrition- releases lipophilic substances, regulates the intercellular fluid composition o mechanical support of neurons o they create a glial scar on the injury - contain GFAP - a glial fibrillar acidic protein from which are intermediate filaments made - types o Protoplasmic - envelop neurons and blood vessels in the gray matter of the brain and spinal cord o fibrillar - longer protuberances, rather in white matter

Answer 177

- smaller, less intermediate filaments, darker cores - both in grey and white - they have many protuberances, each adhering to the axon and forming its myelin sheath

Answer 178

- smallest glia, dark elongated nucleus, thorny appearance - they are macrophages in the nerve tissue - moving, phagocytic o origin is not a glia, but a monocyte

Answer 179

- a special cylindrical epithelium lining the inside of the cerebral ventricles and spinal canal - neuroepithelial neural tube remnant - moving cilia, nexs and zonulae adherentes - tanycytes (in the 3rd chamber) are ependymal cells

Answer 180

- oligodendrocytes are not on the periphery - myelin sheaths on the periphery are made by Schwann cells - difference mainly in myelin count - oligodendrocytes envelop several axons, Schwann cells only one

Answer 181

- they represent astrocytes on the periphery - they take care of neurons

Answer 182

- in the CNS lies freely between the neural projections and the glia - in PNS lies in simple slits of Schwann cells

Answer 183

- myelin consists of layers of modified membranes - thicker (more proteins) and thinner parts alternate in myelin - Nodes of Ranvier ʹ between Schwann cells o excitement spreads from one node of Ranvier to another - much faster - internodium- distance between the nodes of Ranvier o 1-2 mm in PNS, in CNS are shorter - Schmidt- Lantermann clefts - these are parts of the Schwann cell cytoplasm that have been inserted into the myelin sheath and where axon nutrition takes place

Answer 184

"PNS are cables of conducting the excitement from the neuron to the periphery and back to the CNS" - nerves o nerve fibers ʹ grouped into bundles o connective tissue - epineurium, perineurium and endoneurium - ganglia o accumulation of cells o ovoid structure o enveloped by dense connective tissue o satellite cells o ganglia of the spinal cord sensory ʹ pseudounipolar neurons o ganglia autonomic efferent multipolar neurons distributed evenly satellite cells layer

Answer 185

- The ability to perceive and respond to fluctuations in nutrient levels is one of the conditions of life, one of the evolutionary pressures - nutrients (or macronutrients) are important for energy production and construction - essential (we are not able to synthesize) x non-essential molecules (we can make them) our body perceives both o specifics of AA: de novo synthesis x necessary food intake - we have different pathways of perception of IC and EC levels of carbohydrates, AA, lipids + many metabolites - integrated and coordinated thanks to hormonal signaling at the whole-body level - sufficient nutrients support anabolism and storage X deficiency supports the mobilization of reserves, autophagy - nutrient perception: 1) direct binding of the molecule to the "sensor" 2) indirect mechanism due to the detection of another molecule reflecting the occurrence of nutrients (e.g the concentration of the monitored molecule changes depending on the number of nutrients) - the ability to record fluctuations in nutrient levels (correct setting, physiological fluctuations) o e.g. glucokinase = glucose sensor, high KM needs a higher Glc concentration to be captured by glucokinase o If the molecule is unable to sense fluctuations, then it is not a sensor

Answer 186

- unicellular organisms directly exposed to fluctuations in the environment and respond both to changes in intracellular concentration and surrounding levels - most cells of multicellular organisms are not directly exposed to changes in nutrient levels in the environment - there are homeostatic mechanisms aimed at keeping circulating nutrient levels within a narrow range o most of our cells have no contact with the external environment, there are special populations of cells to perceive the state of the internal environment and maintain homeostasis o For example, in pancreatic cells, cells monitor the Glc concentration and produce insulin in response to its concentration - levels nevertheless fluctuate: there are both IC and EC nutrient perception mechanisms

Answer 187

- lipids are a large and diverse group of nutrients (FA, cholesterol, TAG, etc.) with hydrophobic molecules - many roles: energy storage, membrane formation, signal generation. molecules, preservation of vitamins - because of their non-polar nature, they do not typically occur freely dissolved in an aqueous environment: "packaged" in lipoproteins or micelles or bound to proteins (blood albumin)

Answer 188

- GPCR ʹ are G-protein coupled receptors - perception both in the external environment and within the organism - GPCR/Free fatty acid receptor: GPR40/FFA1 a GPR120/FFA4 detecting long unsaturated FAs - GPR40 for beta cell pancreas are enhanced by glucose-stimulated insulin secretion - when both Glc and FA are delivered, secretion is increased - GPR120 in GIT: production of intestinal hormones incretins, eg GLP-1 (glucagon-like polypetide 1), showing insulinotropic effects in beta cells. - if GIT finds that it has both FA and Glc, it will promote insulin secretion through incretins - GPR120 in adipocytes, white fat tissue.: induction of glucose entry into them - meaning: one nutrient increase (FA) prepares the body for an immediate increase in another nutrient (Glc) - typically a mixture of nutrients in the diet, not just one of them - there are also FFA2/GPR43 a FFA3/GPR41 which bind short-chain FA produced by intestinal bacteria - activation leads Gq-dependent processes to increase cytosolic Ca2+ concentration and wash out GLP-1 - FA directly or indirectly assist insulin secretion and glucose entry into the cell

Answer 189

– hormones secreted by adipocytes - Systemic effects: securing energy homeostasis, appetite regulation, energy expenditure - leptin: sensor of high lipid stores o leptin receptor is found in the CNS (in the hypothalamus, where it acts as anorexigenic = suppresses appetite) and in peripheral tissues - Leptin or leptin receptor defect: hyperphagia, morbid obesity - adiponectin: levels inversely correlated with the amount of fat stores - supports insulin sensitivity and energy expenditure (correlation with obesity and T2DM), participates in insulin secretion o Adiponectin is reduced in morbid obesity

Answer 190

- signaling from G protein-coupled receptors - perception of cholesterol levels enables regulation of energy-intensive biosynthesis - active in the case of insufficient dietary intake; a close link with the de novo synthesis - there must be a lot of energy for cholesterol synthesis, if it is not, the ATP / AMP ratio will be reduced and AMPK will be activated, which phosphorylates HMG - CoA reductase and inactivates it - cholesterol-detecting protein SCAP (SREBP1 cleavage activating protein) directly binds cholesterol via „sterol sensing domains (SSDͿ“ - SCAP onstitutively binds SREBP (Sterol Regulatory Element-Binding Protein) - anchored in membrane ER - signaling from G protein-coupled receptors - high cholesterol: binding of chol. to SCAP, causes a conformational change that prevents activation of SREBP (the complex remains anchored in the ER membrane - increased binding to anchoring protein in the INSIG membrane) - if we have enough cholesterol, the cell does not need to synthesize more - low cholesterol: SCAP without chol. -> release of SCAP/SREBP complex from anchor protein translocates to GA where proteolytically cleaved - release of cytoplasmic N-terminus of SREBP, the remainder is transported to the nucleus and induces transcription of genes de novo cholesterol production - increased production of chol. ʹbound of chol. on SCAP- negative feedback - not only SCAP binds cholesterol - perception of sterols also occurs at the level of HMG-CoA reductase - rate-limiting enzyme de novo cholesterol synthesis o high levels of intermediates of chol. synthesis inhibits its activity

Answer 191

- A number of processes to maintain stable blood glucose - complex regulation at different levels: IC, EC, external environment - interplay of a number of hormonal signals: the best known pair of insulin / glucagon

Answer 192

- catalyzes the first step of IC metabolism of Glc - the beginning of a series of processes - hexokinase IV, only this isoenzyme functions as a Glc sensor - has a high Km ʹ lower affinity for Glc (half saturation at 8 mmol / l conc.) - its activity varies within the physiological range of glycaemia - it is active in excess glucose - is the basis of simple and direct IC perception of Glc - it also determines glucose homeostasis of the whole organism - located in the liver and beta cells of Pancreas - role in the organism: o glycogen degradation and gluconeogenesis in Glc deficiency / glycogen formation and glucose degradation with sufficient o GCK is the most abundant liver hexokinase - inactive in Glc deficiency - allows the export of dephosphorylated Glc from hepatocytes to the extracellular environment

Answer 193

- EC glucose level sensor - similar to GCK, GLUT2 has a higher Km (20 mM) than other GLUT - on one side of the transmitter there must be a large concentration of Glc for the molecules to be actively transferred to the other side - low affinity of GLUT2 conditions effective glucose transport to cells only when blood glucose is high (other GLUTs are saturated much earlier) - mechanism of operation. o Glc entry into hepatocytes through GLUT2 - GCK-dependent phosphorylation and onset of metabolism o low glycaemia ʹ hepatic glycogenolysis and gluconeogenesis increases Glc levels in hepatocytes - GLUT2 transmits in both directions - Glc is exported to the circulation o for both processes the increase must be significant! o This switching is key to keeping blood glucose constant

Answer 194

- pancreatic beta cells play a highly-specialized role in the perception of glucose levels in the EC environment o ensure the production and secretion of insulin - insulin secretion is pulsatile, mainly in response to increased blood glucose - mechanisms: o increase in plasma glucose o increase in B-cell glucose - transport through GLUT2 / GLUT1 (mouse models / humans) o 3) glucokinase phosphorylation o increase in glucose oxidation - glycolysis and ATP gain o increase in ATP in the cytoplasm o 5) closing ATP-controlled K + channels o 6) depolarization (opening of voltage-controlled Ca2 + channels) o increase in cytosolic Ca2 + - an increase in Ca 2+ in B cells leads to exocytosis of insulin and reopening of the K + channels

Answer 195

- do not play the role of blood glucose sensors! - GLUT4 expression in skeletal muscle and adipose tissue - postprandial glucose processing/storage - insulin initiates translocation of GLUT4 into the membrane of the respective cells - these processes start only after secondary mechanisms of glucose perception (pancreas and liver) have been fulfilled to assess the excess glucose - occurrence of GLUT1 in germinal tissues - low KM resulting in its permanent saturation and therefore even delivery of Glc

Answer 196

- it is necessary to identify and predict the nutritional value of food before the actual digestion process takes place - taste buds - 5 flavour categories: sweet, umami, bitter, sour, and salty - apical membrane of cells exposed to the environment contains taste receptors, eg T1R and T2R families (GPCR) - a heterodimer composed of T1R2 + T1R3 forms a taste receptor for glucose and sweeteners - signalling results in NT release - taste receptor for Glc are also in intestinal epithelium - production of intestinal hormones incretins (GLP-1) - support of insulin secretion - artificial sweeteners can activate incretin secretion, nutrient absorption (and other processes) independent of nutritional value - intake may lead to a higher risk of developing metabolic diseases such as T2DM and obesity

Answer 197

- protein synthesis is energy intensive and highly complex, therefore, the cell has receptors that perceive if they have any AMK deficiency - they do not want to stop protein synthesis in half if they lack AA - cells, therefore, perceive EC and IC levels of AK and associate them with their processes - in the absence of AA, proteins represent reservoirs of AK - their mobilization by degradation (proteasome / autophagy) - recycling of AA - no AA is able to replace the other!

Answer 198

- serves to stop proteosynthesis if AA is deficient - detects uncharged tRNA, independent of their AA-specificity - uncharged tRNAs accumulate due to lack of free AA - GCN2 has high affinity for uncharged tRNAs - elegant example of perception of nourishment indirectly through detection of associated molecules - low AA levels: binding of GCN2 to uncharged tRNA, causing a conformational change leading to kinase activation and inhibition of phosphorylation of the key early eIF2α ; eukaryotic initiator factor 2 alpha) translation activator

Answer 199

- GPCR - T1R family (heterodimer T1R1 + T1R3): detection of AA presence - umami taste = glutamate taste - human AK receptors show a particularly high affinity for glutamate (however, other L-AKs also act as ligands, D-AKs do not) - activation of G protein leads to NT release - transfer to CNS - taste receptors are not only in the oral cavity, but also on the endocrine cells of the intestine o instead of neurotransmitter excretion, the incretins are released through blood G-protein activation - they prepare the organism for increased occurrence of nutrients and their processing

Answer 200

- source is air - regulation of minute ventilation (respiratory rate and tidal volume) - peripheral chemoreceptor system responsive to changes in O2 partial pressure - groups of chemoreceptors distributed in the vascular system ʹ the highest density in carotid bifurcation and in the aortic arch aortic bodies - perceive a decrease in pO2 - transmission of neurotransmissions to the respiratory centers (brain stem) - hyperventilation - the combination of high O2 consumption in MIT and affecting AMPK may be an explanation - cells respond earlier than other cells - AMPK activated by decreasing ATP / AMP ratio! - AMPK can modulate the activity of the 2 most common K + channels by phosphorylation - inhibition of K + channels - membrane depolarization - IC Ca2+ increase (after membrane depolarization) - NT spill - mechanism: o low pO2 ---- cells in carotid bifurcation feel a lack of ATP ---- in the cell a large amount of AMP ---AMPK----channel modulation for K + (phosphorylation)--- switch off channels---membrane depolarization--- increase of IC CA2+ ----spill of neurotransmitter hyperventilation

Answer 201

- AMP-protein kinase = lack of energy sensor - it is activated by an increase in the AMP / ATP ratio - it is an energy cell sensor - causes the depletion of ATP-consuming pathways (anabolic processes) in favour of ATP-forming pathways (catabolic processes) - eg stimulates β-oxidation of MK and glycolysis, on the contrary inhibits lipogenesis or proteosynthesis - inhibits pathways that are energy intensive while activating pathways in which energy can be obtained - importance: to modulate the metabolism of cells to maintain their energy balance

Answer 202

- Information in the nervous system is transmitted chemically (neurotransmitters between cells) and electrically (membrane potential in one cell)

Answer 203

in neurons it's between -60 to -80 mV o Negative value is by convention ʹ inside is negative, outside is positive o This is due to the different membrane permeability and ion concentrations Na+ - 140mM outside, 10mM inside, cannot pass through the membrane K+ - 4mM outside, 100mM inside, can pass through membrane ʹ trying to balance the concentration on both sides of the membrane, by coming out of the cell it is as if it was taking positive charge with it

Answer 204

ʹ reduction of membrane potential below the resting value (intracellular space becomes less negative) o can occur in all cell types o arises in response to some event/stimuli ʹ on dendrites, for example, it arises after the interaction with an excitatory neurotransmitter excitatory neurotransmitter opens ion channels and positively charged ions begin to flow into cell o depolarization spreads on the membrane as a wave, but like a wave it gets gradually weaker and weaker the body (soma) and dendrites of the neuron are constantly developing small depolarizations, which spread on the membrane in all directions, intensity gets weaker from origin there is an initiation segment, in the proximal axon. When this spot is well depolarized (from ---70mV to about -50mV, like on the graph) there will be an action potential x many small depolarizations, which arrived to this initiation segment from different parts of the body and neuron dendrites trigger the action potential

Answer 205

ʹ specific type of depolarization that spreads rapidly and arises only on neuronal axons o axons contain a large number of voltage-gated sodium channels that are closed at rest and all open at once during an action potential o when sodium channels open. Sodium starts to flow inside, which causes a rapid and even higher depolarization after a few milliseconds after the opening eg. the sodium channels, the channels then close again/block regardless of the current potential blocked sodium channels do not leak any ions and can only be reopened by first switching to the closed state and THEN to the open state sodium channel has thus 3 states - closed (deactivated)-> open (activated) -> blocked (inactivated) blocked sodium channels are only switched to the closed state after the membrane potential is returned to the resting value ʹ this principle prevents the propagation of action potential o during depolarization, the membrane potential gets positive ʹ this is called overshoot o after sodium channels are blocked only potassium channels remain open o because sodium channels are closed and potassium͛s are open͕ the outflow of potassium outweighs and the membrane potential begins to move to a resting value ʹ repolarization o However, repolarization proceeds too fast and the membrane potential drops to -100mV This is called hyperpolarization (undershoot) o In order for a neuron to spread another signal, we must return the ions to their original places, which is why there are Na+/K+ ATPases=> Na+ goes to extracellular space and K+ to the intracellular

Answer 206

- tetrodotoxin ʹ is a blocker of voltage-gated Na+ channels, which leads to respiratory arrest o it is synthesized by bacteria that live symbiotic with the Japanese Fugu fish o lethal dose is in milligrams

Answer 207

- signal transmission between cells - communication occurs by signalling molecules ʹ neurotransmitters o although a few signals are propagated by electrical mechanisms (e.g gap junctions), there are only a few - presynaptic neuron ʹ contains vesicles with neurotransmitters, MITs, transporters for neurotransmitters, Ca2+ channels and presynaptic receptors, which provide feedback on the situation in the synaptic cleft - postsynaptic neurons ʹ postsynaptic receptors whose function is signal transduction - astrocyte ʹ belongs to macroglia (large glial cells) o play an essential role in synapses ʹ their function is neuronal nutrition and isolation (they prevent the spread of excitement outside the synapses) o are also very important for the construction and function of blood- brain barrier - action potential spreads through the axon until the synapse, where depolarization opens voltage- gated calcium channels o calcium enters cell and is an essential stimulus for exocytosis of vesicles with neurotransmitters

Answer 208

- SNARE proteins play a role in the fusion of vesicles (full of neurotransmitters) with the presynaptic membrane o v-SNARE proteins ʹ in vesicles, located on the vesicle itself e.g. synaptobrevin o t-SNARE proteins - t as target, located on the membrane e.g. SNAP-25 and syntaxin o all SNARE proteins have one specific helical domain (SNARE domain), which tends to bind strongly to another SNARE domain ʹ like Velcro synaptobrevin and syntaxin have one SNARE domain, SNAP-25 has two - other proteins involved in exocytosis o synaptotagmine ʹ acts as a calcium receptor ʹ binds calcium, alters its conformation and triggers the SNARE protein junction, bringing the vesicles close to the presynaptic membrane and they fuse o NSF - ATPase, which unravels SNARE proteins and creates a new empty vesicle via a complex process

Answer 209

- they are large molecules - they are toxins that have the character of an enzyme -> specifically proteases - bacteria of the genus Clostridium o botulotoxin ʹ causes botulism (paralysis, death from respiratory arrest) used in cosmetics (botox), where it paralyzes muscles and smoothes wrinkles o tetanotoxin ʹ causes tetanus (convulsions) - both toxins specifically destroy SNARE proteins, but both target other neurons excitatory/inhibitory- therefore have exactly the opposite effects, although both toxins inhibit the same process o botulotoxin cleaves SNAP-25 in cholinergic (excitatory) neurons = blocks muscle action = paralysis o tetanotoxin cleaves synaptobrevin in inhibitory neurons = blocks muscle relaxation = convulsions

Answer 210

neurotransmitter (NT) a substance released by a neuron to a target cell, in which it induces a specific response by binding to a receptor in the postsynaptic membrane -> binding of NT to the receptor is transient and lasts mostly only milliseconds to minutes, while the effect of the NT can be quick or persist for several days to weeks process of NT transfer from the presynaptic neuron to postsynaptic receptor - synaptic transfer= neurotransmission o Neurotransmission targets cells in the vicinity of the neuron͛s end from which they are released o it is intercellular communication o NT acts on the target cell, but also on the neuron itself ->regulating the amount of NT released (via presynaptic receptors) NT synthesis and release => typical for neurons, but some glial cells can also do it -> astrocytes o NT synthesis usually occurs directly in the synaptic ending (peptides are formed in the body) the rapid effects of NT are mostly mediated by ionotropic receptors, which act as (or are associated with) ion channels o binding NT -> channel opening -> membrane potential change -> AP long-term effects are based on metabotropic receptor binding o NT binding -> G-protein -> intracellular signalling pathways -> regulation of gene expression or function of pre- existing enzymes Through blood brain barrier (BBB) the NT gets into the CNS in the form of precursors -> specific in BBB => there are specific transporters in BBB that allow precursors to pass (finished NTs do not cross this barrier Æ not in the brain direction) o this is especially important for the treatment of some neurological diseases -> eg Parkinson's disease - we will not administer dopamine directly, but instead give its precursor L-DOPA (see below) x Parkinson's disease -> neuronal death mainly in the substantia nigra (dopamine producing neurons)

Answer 211

large molecules o peptides: β-endorphin, leu-endorphin, substance P o endogenous cannabinoids Small molecules o AMK: glutamate, aspartate, glycine o AA derivatives: GABA, catecholamines (noradrenalin, adrenalin, dopamine), serotonin o acetylcholine o other: purines (ATP, ADP, adenosine), gas (NO)

Answer 212

Gamma-aminobutyric acid (GABA) is a major inhibitor NT in CNS GABA-shunt (cycle ʹ synthesis and inactivation of GABA) The majority of GABA is produced by decarboxylation of Glu (enzyme glutamate decarboxylase; cof. PLP) ʹ an important link between glutaminergic and gabaergic signaling o NT is expelled into the synaptic cleft -> is recovered mainly by astrocytes, where it is converted to Gln (= the main precursor of GABA): x GABA in astrocyte -> transamination (amino group replaced by aldehyde group) -> formation of succinate semialdehyde (enzyme GABAtransaminase) -> oxidation -> formation of succinate, which joins into KC, where it produces α-ketoglutarate -> transamination, amination -> Glu formation -> ATP is and NH3 forms Gln -> transmission to the neuron is produced o Gln in neuron is converted to Glu (enzyme glutaminase), from which decarboxylation produces GABA

Answer 213

glutamate (Glu) is the main excitatory NT in CNS (40% synapses) => helps in the preservation of memories and the learning processes from blood to CNS normally Glu does not pass -> essentially only from CNS to blood o cooperation between neurons and adjacent astrocytes is crucial for the production and inactivation of Glu o Glu is excreted by the neuron into the synaptic cleft -> binds to receptors -> causes a change -> released from the receptor -> re-uptake x some NT is taken up by presynaptic neurons but most are taken up by astrocytes (EAAT1 a EAAT2 transporters o in astrocytes glutamate is converted to glutamine (Gln) with glutamine synthetase enzyme (ATP and NH3 consumption) -> Glutamine is then transported to the neuron where it is re-converted to Glutamate, in which the glutaminase enzyme participates NH3 easily permeates through the BBB and binds to Glu - the formation of Gln => this is a problem in some diseases where the concentration of ammonia in the blood rises (eg liver disease) Hepatic encephalopathy => Summary of symptoms manifested in acute liver failure - the liver loses the ability to detoxify the body -> a lot of substances accumulate in the body, eg NH3, which gets into the CNS in an excessive amount -> depletion of ATP (exhaustion) -> dysregulation of NT systems (glutamate, GABA)

Answer 214

acetylcholine (Ach) ʹ chemical structure of quaternary ammonium compound Ach occurs in the neuromuscular plate, in presynaptic neurons in autonomic NS, in postganglionic neurons of parasympathetic nerve, in CNS => regulates waking/sleep the indirect precursor of ACh is a serine Ach is an ester of choline and acetate it is synthesized in essentially one step where acetyl is transferred from AcCoA to choline (it catalyzes the enzyme choline acetyltransferase) o almost all choline gets into the brain from the blood, its synthesis is located almost exclusively in the liver -> it is formed by triple methylation of ethanolamine (SAM is the donor of methyl groups) ethanolamine is formed by the decarboxylation of serine o end of cholinergic transmission - acetylcholinesterase (AChE = enzyme found on the postsynaptic membrane) -> choline and acetate are formed again by AChE---- choline is transported to the presynaptic neuron where it can be used for further synthesis AChE is not substrate specific -> also hydrolyzes other choline esters damage to cholinergic neurons is related, for example, to Alzheimer's disease -> its treatment is by inhibiting AChE function by various drugs (donepezil -> penetrates through the BBB) also related to eg myasthenia gravis (autoimmune disease affecting skeletal muscles - impaired communication between nerve fibers and muscles) -> again blocking AChE through medications (eg neostigmine -> does not penetrate BBB)

Answer 215

catecholamines (derived from L-tyrosine) -> noradrenaline, adrenaline, dopamine o the prefix catechol means binding of 2x OH to the benzene ring the finished catecholamines do not cross the BBB -> they are formed directly in the CNS cells o this must also be taken into account in a number of diseases -> eg Parkinson's disease (insufficient synthesis of dopamine in the CNS => during treatment, we administer to the patient L-DOPA, which crosses the BBB and stimulates dopamine production)

Answer 216

o hydroxylation of tyrosine -> decarboxylation of L-DOPY (= L-dihydroxyphenylalanine) -> hydroxylation of dopamine -> methylation of noradrenaline o DOPAdecarboxylase is commonly called - decarboxylase - L - aromatic amino acids, also useful in serotonin metabolism

Answer 217

it is conditioned by the re-uptake of catecholamines o Catechol-o-methyl transferase (COMT) -> catalyzes the methylation of the hydroxyl group of catecholamines x noradrenalin -> normetanephrine x adrenalin -> metanephrine x dopamine -> 3-methoxytyramin o Monoamine oxidase (MAO) -> catalyzes the oxidative deamination of catecholamines (found in MIT bound to the outer mitochondrial membrane, belongs to flavoproteins, and contains covalently bound cofactor FAD) metanephrine / normetanephrine -> vanilmandelic acid (VMA) VMA is excreted in the urine and is used to determine the production of catecholamines in the body -> it is also used for suspected adrenal marrow tumour (pheochromocytoma) 3-methoxytyramin -> homovanilic acid (HVA) clinical association with MAO -> MAO inhibitors (MAOI - selegiline, moclobemide) are used for the treatment of depression or Parkinson's disease

Answer 218

glycine shows significant inhibitory activity (especially in the spinal cord in the grey matter) -> acts in the CNS via ionotropic receptor coupled with Cl-channel (thus causing hyperpolarization = inhibition) and also as an allosteric modulator (co-activator) of NMDARs activity (glutamate-cationic receptor) channel) Serine formation strychnine (very bitter) is a glycine receptor antagonist => uncoordinated spread of irritation - seizures

Answer 219

histamine is produced by the decarboxylation of histidine (the enzyme histidine decarboxylase) released histamine is then rapidly degraded in two ways: o histamine-N-methyltransferase (HMT/HNMT, co-factored by SAM) -> preferential pathway in CNS o Diaminoxidase -> Not found in the CNS and performs oxidative deamination

Answer 220

it has a similar role to the noradrenergic system -> it also modulates the activity of other systems serotonin is derived from L-tryptophan o serotonin = 5-hydroxytryptamin (5HT) the name of serotonin is derived from its occurrence and effect (it is a blood serum substance that acts on smooth muscle tone the synthesis takes place in two steps: o hydroxylation of tryptophan in position 5 => 5-hydroxytryptophan (enzyme tryptophanhydroxylase) is formed o decarboxylation of 5-hydroxytryptophan => 5-hydroxytryptamine or serotonin (enzyme 5-hydroxytryptofandekarboxyláza) termination of neurotransmission -> reuptake and intracellular inactivation (catalyzes MAO and aldehyde dehydrogenase) => during inactivation, 5-hydroxyindolacetate (5-hydroxyindole acetic acid = 5-HIAA) is produced, which is mainly excreted in the urine as a glucuronic acid conjugate (the 5-HIAA assay is used to diagnose serotonin- producing tumours - neuroendocrine tumours) side metabolic pathway of serotonin => it forms melatonin in the pineal gland (acetyl is attached to the amino group of serotonins and subsequently, methyl is attached to the hydroxyl group)

Answer 221

ribosomes are needed for synthesis -> they are formed in the body of neurons, from where they are subsequently transported by axonal transmission to the nerve endings first, a large parent molecule is formed which is subsequently cut into smaller peptides o e.g POMC (proopiomelanocortin), which produces beta-endorphin, MSH (melanocytes stimulating hormone), ACTH͙ removal from synaptic cleft => mostly degradation, not reuptake the group of peptide NTs is very broad: o opioid substances (they bind to opioid receptors) -> eg endorphin o substance P (GIT motor stimulating peptide) o neuropeptide Y (mediates the effect of leptin on appetite) o somatostatin o cholecystokinin (produced in the small intestine, it is released upon the arrival of grass in the intestine - mainly fats, leading to emptying of the gallbladder and probably to the formation of digestive enzymes in the pancreas)

Answer 222

anandamide (arachidonoylethanolamide, AEA) = arachidonic acid and ethanolamine derivative o name anandamide is derived from Sanskrit ananda (bliss, perfect happiness) specific type of signalling -> retrograde neurotransmission: o synthesized in postsynaptic neuron -> diffuses into presynaptic neuron where it regulates NT release

Answer 223

synthesis from arginine, more in course IV, cofactor NADPH NO synthesis can be - constitutively active (Ca2 + activated, pressure regulation, etc.) / inducible (immune system) possibility of retrograde signaling

Answer 224

signalling molecules (including neurotransmitters) usually have several types of receptors, which very often have different signalling cascades and thus different effects on the cell o the specific effect of the neurotransmitter, therefore, depends on the receptors it is attached to - the tissues often differ by the receptors they express and therefore two tissues can react differently to the same signalling molecule - basic division of receptors o ionotropic receptors ʹ ligand dependent ion channels o metabotropic receptors ʹ everything except ion channels (kinases, receptors coupled with G proteins)

Answer 225

- most abundant system - division of receptors into two basic groups o ionotropic receptors - excitatory, 3 subtypes ʹ are named after their agonists NMDA receptor - besides glutamate it is able to bind other substances at the resting membrane potential, the NMDA receptor is blocked by magnesium ion and the membrane must at least partially depolarize in order to get Mg2 + out so called coincidence detector ʹ 2 signals must be present to open it (glutamate + mem. potential) AMPA receptor kainate receptor o metabotropic receptors (mGluR) ʹ a lot of effects, one of the most known is the 5th taste - umami (all are G-protein coupled receptors)

Answer 226

- GABA is the most important inhibitory neurotransmitter - receptor division into two basic groups, both of which are inhibitory o ionotropic - GABA A ʹ ion chloride channel o metabotropic - GABA B ʹ couple with Gi protein

Answer 227

- uses adrenalin + noradrenalin from the adrenal medulla - Noradrenaline is more important in the CNS - All adrenergic receptors are coupled with G proteins o divided into two types ;α and β which differ in their affinity to the ligand noradrenalin has a higher affinity for α receptors adrenalin has a higher affinity for β receptors

Answer 228

- they are further distinguished into α1 and α2 α1 receptor - excitatory, is coupled with protein Gq - causes activation of PLC -> hydrolysis of PIP2 to IP3 and DAG -> increase of Ca2 + level and other things, but in the neuron Ca2+ itself causes an excitatory reaction α2 receptor - inhibitory, mainly in CNS, is associated with Gi protein - inhibits adenylate cyclase ->decrease in cAMP activity -> decrease in PKA activity -> inhibitory reaction of cells a2 are mainly presynaptic receptors - they regulate the feedback regarding neurotransmitter secretion

Answer 229

they are divided into β1, β2, and β3 but all are coupled with Gs protein Gs protein increases adenylate cyclase activity -> higher cAMP activity -> higher PKA activity higher PKA activity may induce both excitatory and inhibitory reactions, depending on the cell type β1 receptors -excitatory, in the heart, blood vessels of the skin and GIT, they are responsible for increasing heart rate β2 receptors - inhibitory, in bronchial and vascular smooth muscles, cause smooth muscle relaxation β3 receptors - excitatory, in adipose tissue, cause lipolysis (activate hormone-sensitive lipase)

Answer 230

some tissues have a higher blood supply during stress situations (muscles) and others not (GIT) o α1 receptors and β2 receptors complete each other - both are in the smooth muscle of the blood vessels, and both respond to the same signal by the opposite effect (vessel contraction vs. vessel contraction) the trick is that GIT smooth muscle cells have receptors that respond to adrenaline by contraction, whereas skeletal muscle smooth muscle cells have receptors that respond to adrenaline by relaxing (works well in fight or flight reaction)

Answer 231

- dopamine receptors are labelled with the letter D (D1 to D6), but only D1 and D2 are important to us o both are coupled with G proteins - D1 = Gs protein – rather excitatory, D2 = Gi protein – rather inhibitory - function of dopamine in the brain - in the brain there are 4 basic dopaminergic systems (neural pathways), which are neurons that by via axons elsewhere in the brain secrete dopamine o two main nuclei (neural bodies) in substantia nigra (SN) and ventral tegmental area (VTA)

Answer 232

- from VTA to the cortex in the frontal area of the brain plays a role in correct thinking and understanding of reality - during schizophrenia it is damaged (hyperactive)

Answer 233

from VTA to limbic system part of reward system ʹ nerve circuit in the brain that shows us that something is good, that we should continue doing it - - sex, sweet/fatty food, success plays a big role in the development of addiction - it is activated by a large number of drugs

Answer 234

from substantia niagra to corpus striatum (striated body, full of basal ganglia) basal ganglia are responsible for initiation of stereotyped movement such as walking, cycling - so called muscle memory ͞ is damaged during Parkinson͛s disease

Answer 235

from some other nucleus to the hypothalamus regulates prolactin secretion

Answer 236

- serotonin plays a role in maintaining mood, regulating sleep, eating, perceiving pain͙ - 5HT (5-hydroxytryptamine) is used for serotonergic receptors, some (5HT3) are ionotropic o 5HT1 - rather inhibitory, linked to Gi protein, seems to be somehow related to sleep regulation o 5HT2 - mostly excitatory, coupled with Gq receptor there are 3 subtypes (5HT2A, 5HT2B, 5HT2C) x relatively many hallucinogens (eg LSD) bind to 5HT2A o 5HT3 - excitatory, ionotropic (ligand-controlled ion channels) are important in the regulation of central vomiting - not reflex (finger in the throat), central vomiting iscaused by the brain - it is found that there is something strange in the blood -> severe and unpleasant vomiting 5HT3 receptor blockers are the most effective antiemetics (anti-vomiting drugs)

Answer 237

labelled with the letter H, they are divided into 3 subtypes - H1 - excitatory, mainly in the brain, involved in the regulation of appetite and sleep o coupled with Gq protein, H1 blockers are used as antihistamines (anti-allergic drugs) - H2 - predominantly in the periphery, for example in the gastric epithelium, where they regulate the secretion of gastric acid o coupled to Gs protein - H3 - not very interesting or important for pharmacology o coupled with Gi protein, often receptor in the presynaptic membrane (provides feedback)

Answer 238

- the neurotransmitter is acetylcholine - cholinergic receptors are divided into two basic groups, whose names derive from their pharmacological agonists o nicotinic receptors (nAChR) - excitatory, ionotropic neuromuscular plates, in autonomous ganglia, in the brain (basal ganglia) o muscarinic receptors (M) - coupled to G proteins, there are 5 subtypes M1 - coupled to Gq, are in the CNS, important in memory retention x So called the neuronal muscarinic receptor M2 - linked to Gi, present in the heart (decrease heart rate) the main signaling part of the G protein is the beta-gamma dimer - it activates potassium channels, which inhibits depolarization and leads to decreased excitability of heart muscles so-called cardiac muscarinic receptor M3 - coupled to Gq, mediates the effect of acetylcholine on various exocrine glands (eg salivation) So called the glandular muscarinic receptor Atropine acts as an inhibitor of all muscarinic receptors - therefore it is used as an antidote in poisoning of amanita phalloides (mushroom)

Answer 239

Binds opiates͕ endorphins͕ ekephalins͙ - subtypes marked with Greek letters μ (míͿ, κ (kappaͿ a Δ (deltaͿ - all are metabotropic and linked to Gi protein

Answer 240

- receptor is guanylate cyclase (cytoplasmic enzyme) -> produced cGMP -> activates PKG

Answer 241

- agonists- bind to the receptor and trigger a signaling cascade - antagonists- bind to the receptor and do nothing - partial agonists- they bind to the receptor and, like the agonists, trigger it, but not fully - inverse agonists - they bind to the receptor and do exactly the opposite of what an agonist would do

Answer 242

it is usually not necessary to fill all receptors to fully express the signal ʹ excess receptors - E ( effect) = Emax [L] / EC50 + [L] o EC50 is the ligand concentration at which we achieve 50% effect

Answer 243

agonist- will form some amount of RL complexes that will have some effect - antagonist- the amount of RL complexes will be similar to the agonist, but the effect will always be 0 - partial agonist the amount of RL complexes will be similar to the agonist, but the effect will always be lower than that of the agonist o we do not achieve 100% effect even when all receptors are bound - inverse agonist - the amount of RL complexes will be similar to the agonist, but the effect will be opposite to that of the agonist o if the agonist effect is X, the inverse agonist effect is -X

Answer 244

- first a different ligand will be added and then the agonist o For example, an antagonist is first introduced into the receptor tissue and more and more agonists are added gradually - agonist + antagonist o Kd increases - the agonist will not be as easily associated with the receptor, but 100% saturation can be achieved, it depends on whether the antagonist is competitive or non-competitive, but for the sake of simplicity we will only consider competitive - agonist + partial agonist o same effect as the antagonist - Kd increases because they compete for a receptor binding site

Answer 245

- agonist + antagonist - in the case of no excess receptors, the efficiency curve will be equivalent to the binding curve - agonist + partial agonist - the curve does not start at zero, because some effect has a partial agonist itself o at low agonist concentrations, the partial agonist will increase the effect, but at high concentrations it will decrease - however, Emax can be achieved at an infinitely high agonist concentration - agonist + inverse agonist - the curve starts below zero, then grows to its maximum effect

Answer 246

Drugs that locally prevent pain perception (= block pain transmission) - Voltage-dependent sodium channels are the ideal target for preventing nerve transmission - the first local anesthetic discovered was cocaine - it has a lot of effects, one of which is sodium channel blocking o the other one is blocking (re-uptake) of dopamine o apart from that it also stimulates but at a completely different location ie. It is not due to channel blocking o then it was replaced by synthetic substitutes trying to be like cocaine = lidocaine, procaine, novocaine o apart from tetrodotoxin, which blocks sodium channels from the outside, cocaine and other block from the inside - local anaesthetics are small and hydrophobic, so that they can cross the membrane and diffuse into axons

Answer 247

- their main use is in surgery because the muscles (mainly skeletal) always have some form of tonus, which the surgeon does not want - another use is for intubation - insertion of the tube into the trachea, which allows ventilation

Answer 248

ʹ act on CNS and generally reduce the muscle tonus in the body o acts predominantly as GABA receptor agonists (which are inhibitory) GABAA agonists ʹ benzodiazepines - lexaurine, diazepam (which has other effects) GABAB agonists - baclofen

Answer 249

acting peripherally, directly on the neuromuscular plate - interrupts transmission of a signal from the nerve to muscle o while central muscle relaxants cause a decrease in tone, peripheral muscle relaxants cause muscle paralysis o can be divided into two groups - non-depolarizing and polarizing non-depolarizing- nicotinic acetylcholine receptor blockers x curare (active substance tubocurarin), botulinum toxin, pancuronium (derivative of tubocurarin) depolarizing- instead of blocking nicotinic acetylcholine receptors, depolarizing myorelaxants will permanently open them, but the effect will be the same x depolarizing agonists are very long acting nicotinic acetylcholine receptor agonists x they work by opening channels that inactivate themselves after a while - at this point a normal agonist would step away from the channel, which would close the channel and everything would restart o however, depolarizing myorelaxants do not leave, because the channel is permanently inactivated this results in short-term convulsions and paralysis the agent is succinylcholine, which is currently used for intubation - the paralysis lasts about a minute

Answer 250

- two possible blocking receptors - α1 receptors and β1 receptors o α1 antagonist (alpha blockers) - acts on vascular smooth muscle and blocks its contraction caused by catecholamines prazosin - competitive reversible α1 receptor blocker o β1 antagonist (beta blockers) decrease the effect of catecholamines on the heart, end with -olol propranolol - an older drug, a non-selective β blocker ;blocks all β receptors͕ not just β1) x may cause bronchoconstriction - it should not be given to asthmatics atenolol - selective β1 blocker pindolol - partial agonist β1, no dangerous frequency is reached, as with antagonists they trigger β1 but few͖ it is a pressure stabilizer - it decreases at higher frequencies, increases it at low frequencies o Viagra (sildenafil) does not block α1 adrenergic receptors but inhibits cGMP phosphodiesterase o α and β receptor agonists can also be used o α1 agonists will cause vasoconstriction - for example, nose sprays eg phenylephrine and oxymetazoline o β1 agonists - used in acute heart failure - for a moment they really pump up the heart eg doputamine and isoprenaline o β2 agonists are important for the treatment of acute asthma attack - relax smooth airway muscles - calcium channel blockers o The goal of their effect is vascular smooth muscle, because it is dependent on extracellular calcium The heart muscle needs extracellular calcium as well, but in smaller quantities o Blocking Ca2+ entry into the cell prevents smooth muscle contraction o Ca channel blockers also affect the heart - reducing the frequency and strength of the contraction - nitrates - acts by being metabolized to NO in the body -> causes vasodilation o eg. sodium nitroprusside

Answer 251

- two basic receptors o H1 - central in the brain and peripheral in immune tissues H1 blockers (antihistamines) are administered to block allergic reactions x first generation of H1 blockers also function on brain H1 receptors x newer H1 blockers no longer cross the blood-brain barrier and have no side effects o H2 - in the gastric mucosa, they regulate the secretion of hydrochloric acid H2 blockers are used to block HCl production in patients with stomach ulcers x they are no longer used in hospitals, but they can still be bought in pharmacies

Answer 252

- one of the theories of depression is signaling disorder - lack of serotonin and partly also catecholamines - Most pharmacological drugs for depression function through enhanced transmission of serotonin and catecholamines

Answer 253

- they treat dopaminergic signaling disorders such as schizophrenia - mostly drugs that calm the patients down a lot - they were later found to block dopamine D2 receptors which developed the dopamine theory in schizophrenia

Answer 254

medicines used to calm patients - Anxiety is a very common condition in the population - benzodiazepines

Answer 255

several treatments, all aimed at enhancing dopaminergic transmission o one way is to administer a dopamine precursor (L-DOPA)

Answer 256

- definition - immune system - is an organization of cells and molecules (both mobile and localized) with a specialized role o is able to recognize "own" from "foreign" and sometimes respond o has the ability to recognize right and wrong o is able to maintain homeostasis of the organism - not to harm its own - Main function of immune system o defence - recognizes external pollutants (pathogens), reacts and protects the body o autotolerence - recognizes the body's own tissues and maintains tolerance o immune surveillance - recognizes internal pollutants, i.e. removes old, damaged and some mutated cells - motto of immune system - keep life going in harmony o recognize and neutralize (dangerous) infection or tolerate it if necessary ʹ autotolerance o maintain tissue balance ʹ homeostasis

Answer 257

- substances that the immune system recognizes and responds to - exoantigens - extraneous substances from the external environment; infectious microorganisms and their products - autoantigens - come from the organism itself - allergen - an exoantigen that is capable of eliciting a pathological immune response in a susceptible individual - epitope - a region of an antigen molecule that is recognized by immune receptors

Answer 258

- works on two levels - the first barrier is the body at the places of contact with the external environment o skin- impermeable to microorganisms, produces antibacterial FA o mucous membranes - mucus blocks adherence, mucosal secretions are bactericidal - lysozyme, spermin, gastric juice o intestinal commensal flora - it can block the growth of pathogenic bacteria - the second level is the immune response, which is divided into 2 types: -natural, or primary / congenital / nonspecific -acquired, or secondary / adaptive / specific

Answer 259

o the first line of defence o the simplest form of protection o evolutionarily older - in all multicellular organisms o Phylogenetically preserved - we find it the same in various animals o Includes physical and chemical barriers o general (absence of specificity), rapid response (in the order of hours) o no need for prior contact with the pathogen - the reaction will be to the same extent, no matter how many times the body has already come into contact with the infectious agent - no memory o innate response - all necessary information is permanently written in the DNA and already present in the zygote

Answer 260

o appears later o specific response against (infectious) agent o specific recognition of a small portion of the organism or trigger antigen o the strength of the reaction increases after repeated exposure to a given antigen (infection) o clonal expansion is typical o Memory can be created o The system should eliminate self-reacting cells

Answer 261

- vertebrates and some lower species have natural immunity, form protective enzymes and peptides, have phagocytic cells, have receptors capable of distinguishing their own and foreign, and may reject grafts of another species - human immune system is developed from primitive response of lower organisms - structural barriers, soluble proteins, phagocytic cells - more effective form of immunity is specific immunity - is in higher vertebrates - mammalian immune system is more efficient - uses structures specialized for recognition and regulation - clonal selection hypothesis

Answer 262

- cells of the immune system - are localized throughout the body - the so-called dispersity - leukocytes arise from pluripotent stem cells in the bone marrow along two lines - myeloid and lymphoid

Answer 263

o monocytes - circulate in the blood, then remain in the blood or enter the tissues and differentiate into macrophages o granulocytes - neutrophils, eosinophils, basophils tissue form of basophilsʹ mast cells (mastocytes) o dendritic cells o erythrocyte o thrombocyte - pieces of megakaryocyte cytoplasm o This line forms the basis of the non-specific part of the immune system o Most cells have phagocytosis and produce cytokines o Dendritic cells, monocytes and macrophages are so-called antigen presenting cells (APC), which means that after phagocytosis of a pathogen, it recognizes it and exposes the appropriate antigen to its cytoplasmic membrane, calling appropriate T-lymphocytes to help

Answer 264

o B-lymphocytes - development takes place in the bone marrow, after meeting with the antigen, in the secondary lymphatic organs it transforms to its final stage - plasma cells that produce antibodies o T lymphocytes - development takes place in the thymus, first two distinct precursors are formed Precursors of helper T-cell (TH) - membrane receptor CD4 Precursors of cytotoxic T-cell (TC) - membrane receptor CD8 both precursors only mature after meeting the antigen o NK cells (Natural Killer cells) - do not belong to specific immunity, but behave similarly to T lymphocytes o part of B and T lymphocytes differentiate into memory cells upon encountering antigen, a phenomenon of immunological memory that allows rapid activation upon reunion with the same antigen again - secondary responsed.

Answer 265

primary lymphatic organs - thymus and bone marrow - formation and maturation of immune system cells - secondary lymphatic organs - spleen, lymph nodes, MALT system o MALT - mucosa-associated lymphatic tissue - it is lymphatic tissue in mucosal or submucosal tissue divided into O- (organized) and D- (diffuse) MALT O-MALT - organized lymphatic tissue - cells are gathered together, organized into follicles x Tonsils, appendix, Payers patches (lymphoid tissue of small intestine) D-MALT - diffuse lymphatic tissue - cells are scattered in mucosal or submucosal tissue

Answer 266

- first, non-specific, non-adaptive mechanisms must recognize foreign structures - if foreign structures are harmful, effector mechanisms are activated - phagocytes and humoral systems (proteins) that kill these pathogens o Some phagocytes are essential for initiating specific immune processes e.g. antigen presenting cells - mainly show MHC glycoproteins

Answer 267

natural immune cells have receptors that look for typical structures of microorganisms o these receptors are encoded by several genes directly in the DNA o receptors are looking for a very limited number of molecular structures common to many microorganisms - the so-called highly conserved structures (meaning they have not changed much during evolution) - danger signals o PAMPs - Pathogen Associated Molecular Patterns o DAMPs - Danger Associated Molecular Patterns in case of endogenous cell damage or death These include Heat Shock Proteins, urate crystals, nuclear proteins

Answer 268

- based on the clonal and anticipatory principles - a large number of different B and T lymphocytes are prepared - if an antigen enters the body, it will eventually encounter a lymphocyte with the appropriate receptor o lymphocyte recognizes the antigen and immediately multiplies - clones - two types of specific immunity o cellular immunity - T lymphocytes activate macrophages or signal cells to apoptosis o immunity (humoral) - B- lymphocytes produce immunoglobulins Natural and acquired immune response work together to recognize structures (and eventually eliminate them - pathogens)

Answer 269

- physiological responses to the damage of the organisms integrity - stimuli - chemical, physical, infectious microorganisms, ischemia - Acute inflammation is a physiological defence reaction, but chronic inflammation is usually pathological

Answer 270

- toxigenic bacterial infections o exotoxins - exclusively virulent factors, immunity against them eliminates infection o endotoxins - encapsulated bacteria o microorganisms bypass phagocytosis by the formation of surface polysaccharides - intracellular bacteria (similar to fungal and parasitic infection) o bypasses immunity as they grow intracellularly, especially in phagocytes o T-cell lymphatic response is essential (they can induce apoptosis of cells)

Answer 271

- individuals with immunodeficiency have more severe viral infections - T lymphocytes are more important than antibody production in a number of viral infections o Antibodies are important for minimizing reinfection, especially on mucous membranes - immune memory is often successful in preventing secondary disease

Answer 272

- extracellular parasites - production of antibodies, extracellular cytotoxicity is produced - intracellular parasites - induction of TH1 response and activation of macrophages (leischmania, plasmodium, toxoplasma) - Many cytokines stimulate the natural and acquired immune response - the outcome of infection is determined by the balance between cytokines and effector cells protective or promoting infection o This is often a mixed immune response leading to persistent subclinical infection - a persistently infected individual may develop a clinical disease if the immune system is weakened (eg AIDS)

Answer 273

- NK cells kill many types of tumor cells - macrophages can inhibit tumour growth

Answer 274

- negative - immunodeficiency (SCID - bubble baby) - positive - autoimmunity (T1DM, SLE), allergy (atopy, anaphylaxis)

Answer 275

- recognition of strange, dangerous or bad - fight (occasionally) and tolerate when needed - two branches - innate and adaptive o both composed of cells and soluble products

Answer 276

- macrophages are guardians of innate immunity - we can think of them as soldiers standing on guard at the skin and mucous membranes, ready to eat every pathogen they come across - monocytes are produced in the bone marrow and released into the blood where they circulate +/-3 days o After they enter the tissue and settle, they are called macrophages o the naming of macrophages is different according to the tissue - they are called Kupffer cells in the liver, microglia in the CNS or osteoclasts in the bones, but they are still macrophages - preform 3 main functions 1) phagocytosis 2) produce cytokines 3) present antigens to the adaptive immune system APCs include cells producing MHC II, CD80 and CD86

Answer 277

o In resting state, they travel through tissues and collect dead and dying cells o In activated state, they become effective phagocytes and killers the main activators are PAMPs (Pathogen-associated molecular patterns), which are structures typical of microorganisms - for example, lipopolysaccharides (gram-negative bacteria), peptidoglycan (part of the bacterial cell wall), or bacterial DNA (which is much less methylated than human) PAMPs are evolutionarily highly conserved structures typically found on the surface of pathogens for which they are essential however, there are also endogenous triggers of macrophages such as the cytokine IFN-γ from T-lymphocyte and NK cells

Answer 278

o toll-like receptors (TLR) - a group of receptors that recognize specifically microbial structures such as RNA, bacterial DNA, G-bacterial lipoproteins, flagellin and mucus, they are able to recognize both PAMP and DAMP (damage associated molecular patterns; normally these are molecules that are found in an intracellular environment, but in the event of cell damage these molecules are released into the extracellular environment TLR belongs to PRR (pattern recognition receptors) TLR is found on the cell surface, but also in the intracellular environment the main role of these receptors is to induce the expression of pro-inflammatory cytokines, some adhesion and costimulatory receptors on APC o CD14 - receptor, that recognizes lipopolysaccharides o Fc receptor - receptor that can bind to the Fc portion of antibodies o Scavenger receptors - for modified LDL particles o C3b receptor - receptor that can bind to C3b

Answer 279

MHC II which binds to the T cell receptor CD4 B7, which binds to the T cell receptor CD28 CD40, that binds to the T cell receptor CD40L

Answer 280

- IL-1 and TNF-α are critically important, they also produce IL-6, IL-8 and IL-12 o IL-1 - its action on the hypothalamus increases body temperature = causes fever increases the synthesis of acute-phase proteins in the liver, increases the synthesis of adhesive molecules on endothelial cells, helping neutrophils to penetrate the site of inflammation o TNF-α - like IL-1, causes fever and increases the synthesis of endothelial adhesion molecules, formerly called cachectin because it inhibits lipoprotein lipase in adipose tissue and reduces appetite, leading to cachexia (massive weight loss due to disease) causes intravascular coagulation, which in long-term infection can be dangerous to humans because all of the coagulation wastes coagulation factors and drastically increases blood clotting time o IL-6 - also causes fever and increases acute phase protein synthesis o IL-8 - chemokines that attract neutrophils o IL-12 - promotes the growth of Th1 lymphocytes

Answer 281

- they can be thought of as a backup for macrophages - when a macrophage encounters a pathogen that is not enough, it can call for neutrophils that circulate in the blood (via IL-1, TNF-α and IL-8) - they are by far the largest white blood cell in the blood - they make up about 60-70% of all white blood cells o released into blood after their excretion from the bone marrow o circulate here less than a day - then they die if they are not activated - if they are activated and they penetrate into the tissue their role is phagocytosis o for this work they contain special lysosomes that contain bactericidal enzymes o unlike macrophages, neutrophils are not antigen presenting cells

Answer 282

it is the process by which neutrophils (and other white blood cells) pass from blood to tissues o 1. rolling neutrophils slow down and roll along the capillary wall neutrophils always have a selectin ligand expressed on their surface during an inflammation, IL-1 and TNF (from macrophages) stimulate the endothelium to express selectin selectin ligand and selectin will want to bind to each other, slowing down neutrophil and approaching endothelial wall o 2. crawling - neutrophils slow even more than in the first step ICAM receptor is always expressed on endothelial cells lipopolysaccharides or C5a stimulate neutrophil to express integrin that binds to ICAM o 3. transmigration - neutrophils bind to receptors between endothelial cells and penetrate the tissue o 4. migration to the site of inflammation with the assistance of chemokines such as C5a, IL-8 or IgG

Answer 283

o small / specific / secondary granules - contain many enzymes, e.g. alkaline phosphatase or lysozyme these granules may be fused with a phagosome or be poured into the extracellular space o large / azurophilic / primary granules - contains mainly enzymes acid phosphatase and myeloperoxidase acid phosphatase - degrades proteins in acidic environment myeloperoxidase - an important enzyme for respiratory outburst respiratory outburst is a form of ͞enrage of cells͟; massive production of unstable oxygen radicals involved in killing bacteria these granules can only fuse with the phagosome - they cannot be poured into the extracellular space

Answer 284

a historical name for a condition in which many juvenile neutrophils are present in the blood o occurs in infections when the bone marrow begins to send out unfinished neutrophils

Answer 285

- main function - kills human cancer cells and virus infected cells and produces IFN-γ to activate macrophages - killing of infected cells MHCI are found on the vast majority of nucleated human cells (i.e. not on erythrocytes or platelets) they select a random molecule from the cytoplasm and presents it to the T lymphocytes on its surface x when exposed to a pathological molecule, T lymphocytes destroy this cell = it is a mechanism of defense against intracellular pathogens o Some MHC I viruses bypass the mechanism by simply blocking the production of MHC I no exposure to molecules = no help from T-lymphocytes o NK cells solve this problem by killing all cells having a reduced number of MHC I on their surface

Answer 286

NK cells are lymphocytes- although they belong to innate immunity, they originate from the same developmental line as B and T lymphocytes - contain numerous granules with proteins such as perforin and granzyme in their cytoplasm o perforin - creates a channel on the membrane through which the granzyme can reach the target cell o granzyme - a group of serine proteases that trigger apoptosis by activating caspases

Answer 287

o it is a co-operation of innate and adaptive immunity - antibodies (adaptive immunity) envelop the pathogen and NK cells or eosinophils (innate immunity) destroys it in other ways than phagocytosis o NK cells bind to IgG and destroy pathogen-infected cells o Eosinophils bind to IgE and destroy pathogens, especially large parasites (which are too large for phagocytosis)

Answer 288

o CD16 - binds to Fc part of IgG = important for ADCC o CD56 - aka NCAM (neural cell adhesion molecule) is a commonly used marker of NK cells, but is found in the brain and neuromuscular plates facilitates bonding with other cells

Answer 289

- contain granules with destructive enzymes - can be activated by IgE antibodies - are important in the fight against parasites that kill by releasing their toxic enzymes - are responsible for allergic reactions

Answer 290

- their enzymes - major basic protein (MBP), eosinophilic cationic protein (ECP), eosinophilic peroxidase (EPO), eosinophil-derived neurotoxin (END) - participates in ADCC (antibody-dependent cell cytotoxicity) in cooperation with IgE - IL-5 from Th2 lymphocytes are activated - their proportion in blood should be below 5% - increases in case of parasitic infection or allergic diseases

Answer 291

- originated from myeloid line from bone marrow, matured are found in skin and submucosa - are full granules with mainly pro-inflammatory cytokines, histamine, heparin and leukotrienes - express a high affinity Fc receptor for IgE - are involved in allergic reactions and may cause anaphylactic shock

Answer 292

- they are similar to mast cells but mature in the bone marrow and then circulate in the blood o they do not normally enter the tissue; they do not appear until inflammation - they are involved in some allergic reactions but this is not fully understood yet

Answer 293

- they are called Langerhans cells in the skin - they are professional antigen presenting cells (APC) they collect a piece of antigen and migrate with it to the lymph nodes, where they present it to T lymphocytes o T lymphocytes then travel to the site of infection and do their job - Dendritic cells are basically snitches

Answer 294

the process by which macrophages and neutrophils engulf pathogens and trap them inside their cytoplasm o chemotaxis - at the very beginning of phagocytosis, the phagocyte must reach the pathogen o Adhesion- Once the macrophage comes close to the pathogen, it adheres to it o ingestion- the pathogen gets into the phagocyte the cell structure that binds a pathogen inside a phagocyte is called a phagosome o destruction- inside the cell phagosome associates with lysosome, which contains enzymes that kill and break down bacteria

Answer 295

antibodies are proteins produced by B lymphocytes that recognize specific antigens - we have 5 types of antibodies - A, D, M, E and G

Answer 296

each antibody monomer consists of 2 identical heavy and 2 identical light chains Heavy chains (50-75kDa) are connected by disulfide bridges in the so-called hinge region, where both chains divert and form a characteristic Y-shape Light chains (25kDa) are linked by disulfide bridges to one heavy chain

Answer 297

o since they are peptide chains, they have a C and N terminus C end is the end where 2 heavy chains are side by side N end is the end where 1 heavy and 1 light chain are side by side x this is also the antigen binding site

Answer 298

o each antibody chain can be divided into smaller segments - the so-called domains o A heavy chain is divided into 4 (sometimes up to 5) domains o a light chain is divided into 2 domains

Answer 299

o variable and constant parts differ on both light and heavy chains the variable portion is the first domain at the N terminus of each chain o after this division individual domains can be labelled according to: its variable or constant character (V vs. C) belonging to the heavy or light chain (H vs. L, marked below) order from N end to C end o together we have light chain with CL and VL domain heavy chain with VH, CH1, CH2 and CH3 domain

Answer 300

o Fab region is VL + CL + VH + CH1 o Fc region is CH2 + CH3 binds to complement or cells

Answer 301

- antigen binds to a site between VL and VH - that portion of the antigen that binds to the binding site is called Epitope - the bond between antigen and antibody is o noncovalent ʹ ionic, hydrogen bridges o reversible - the rate of formation and degradation of the bond is based on the affinity of the antibody to the antigen - avidity is the strength of interaction of multivalent antibody with multivalent antigen

Answer 302

- the binding of the antibody to the antigen creates a so-called immunocomplex o This association has different results depending on the type of antibody and antigen - agglutination antibodies accumulate antigens closer to each other - macrophages do not have to run after each antigen, but they can eat many more at once - Opsonisation the so-called flavoring - of antibodies on the antigen increases the chance that the macrophage phagocytoses it - neutralization- antibodies by enveloping the bacterium prevent it from passing through the membranes and by enveloping the toxin may reduce or disturb its biological activity - antibody-dependent cell-mediated cytotoxicity (ADCC) - similar to opsonisation, only phagocytosis helps NK cells and T lymphocytes induce apoptosis in the target cell - complement activation- 2 IgG or 1 IgM can trigger the classical complement pathway

Answer 303

- There are several types of heavy chains and each type has its own class of antibodies o Types of chains - μ (IgM) δ (IgD), Y 1-4 (IgG1-4), α1-2 (IgA1-2) and ε (IgE) - there are two types of light chains (kappa and lambda) but they are not so different - any type of heavy chain can pair with any light chain - light and heavy chains are always identical in one immunoglobulin molecule - besides their specialized localization, all antibodies can be found in blood and lymph

Answer 304

- is a group of proteins produced by immune cells that act as signalling molecules and are responsible for signalling throughout the entire immune response o they affect the synthesis of other cytokines, enhance or cancel the signal of other cytokines, and ensure positive and negative regulation of immune responses - cellular responses to cytokines are mostly slow because they require mRNA and protein synthesis - there are many cytokine subtypes o chemokines - used in chemotaxis, which is the process of attracting cells of the immune system to a certain location, such as an infection site o interleukins- molecules that travel between leukocytes (therefore inter = between leukins) => ensure lymphocyte communication are produced by activated T-lymphocytes (mainly TH) o tumour necrosis factor (TNF) - can cause tumour death (hence the name) and trigger an immune response o interferons - named for their ability to prevent (interfere) the multiplication of viruses o transforming growth factors (TGF) & colony stimulating factors (CSF) - support proliferation and differentiation - their effects may be autocrine, paracrine or endocrine

Answer 305

- pleiotropy of action - one cytokine has several effects, depending on which cell it acts on o for example, IL-4 induces proliferation in mast cells and activation, proliferation and differentiation in B cells - redundancy- many cytokines perform one function - for example, IL-2, IL-4 and IL-5 induce proliferation in B cells o Cytokine receptors are heterodimers and family-like one͛s merge into families (= difficult to diagnose) - synergies- two different cytokines are needed for the signal - individually they don͛t do anything o the presence of both cytokines is required to produce the desired effect - antagonism- one cytokine can cancel the signal of another cytokine

Answer 306

- pro-inflammatory cytokines - anti-inflammatory cytokines - Growth factors - Humoral immunity cytokines - cellular immunity cytokines - cytokines with antiviral potential

Answer 307

produced by activated macrophages, NK-cells and others in response to infection o Their purpose is chemotaxis and killing o IL-1, IL-6, IL-8, IL-12, IL-18, TNF-α

Answer 308

- are mainly produced by T-lymphocytes and are there to inhibit the inflammatory response o IL-1Ra, IL-4, IL-10, TGF-ß

Answer 309

- IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-9, IL-11, IL-14, IL-15, G-CSF (granulocyte-CSF), erythropoietin (EPO)

Answer 310

- IL-4, IL-5, IL-9, IL-13 o participation in B-cell function and antibody production

Answer 311

- IL-2, IL-12, IFN-γ o play a role in T-cell function

Answer 312

IFN-α ͕ IFN-ß͕ IFN-γ

Answer 313

- Interferons - treatment of cancer and viral diseases - IL-2, IFN-γ͕ TNF-α - artificial activation of T lymphocytes in people with immunodeficient disorder - IL-2 and NK-cell activating lymphokine in the treatment of cancer - GM-CSF is used to increase leukocyte count after chemotherapy, bone marrow transplantation and AIDS - anti-cytokine antibodies in the treatment of autoimmune diseases and transplant rejection o for example, anti-TNF in rheumatoid arthritis and anti-IL2R to suppress rejection after transplantation - anti-TNF in the treatment of septic shock - anti-IL-2R-α in the treatment of adult T-cell leukaemia - anti-IL-4 in the future could treat allergies

Answer 314

their function is primarily cell adhesion and signal transmission

Answer 315

Groups of adhesive molecules bind to extracellular matrix components and membrane ligands o ICAM-1 or CD54 membrane integrin that is expressed on endothelial cells white blood cells can stick to it to slow down and pass through the vessel wall selectins mediate this binding on white blood cells

Answer 316

Groups of adhesive molecules - protein structures o The extracellular portions comprise one or more immunoglobulin-like domain domains o CAM, CD80 / 86 (costimulation in T cell activation by B cells), CD2

Answer 317

c a large group of proteins of non-immune origin that are able to recognize and bind sugars o Due to their ability to search for carbohydrate structures, lectins are often found on phagocytes, which use lectin receptors to search for carbohydrate signatures of microorganisms - for example, sugar mannose (6C) o not only for searching - a subset of lectins called selectins allow white blood cells to connect to the vascular endothelium and slow down during diapedesis

Answer 318

Groups of adhesive molecules these are very strongly glycosylated (mainly O-glycosylated) glycoproteins o may be secreted or membrane bound o Some membrane-bound carriers carry oligosaccharide chains and thus serve as a ligand for some selectins

Answer 319

- they are receptors on different cells that can bind Fc portions of antibodies o Fc receptor are specific for individual classes of immunoglobulins - are important for example in phagocytosis or mast cell degranulation - B-cell regulatory function, adhesive function

Answer 320

- molecules on the surface of most (but also exceptions) of cells, which, in addition to their biological function, serve to recognize individual cell types - CD3, CD5 = T lymphocytes o CD4 = T helper lymphocyte o CD8 = cytotoxic T lymphocyte - CD16 = Fcγ ;FcgammaͿ NK cell receptor, which is critical for proper ADCC progression - CD19, CD20 = B lymphocyte - CD34 = on the surface of stem hematopoietic cells - CD79 - molecule associated with antigen specific B cell receptor

Answer 321

the complement system is a humoral component of non-specific immunity - function - opsonization (designation for phagocytosis), chemotaxis, osmotic lysis of pathogen o a total of about 30 serum and membrane proteins, the main ones being C1 to C9 proteins o some of these proteins consist of subfolders, a and b, which can only be activated after cleavage grafts a create a gradient that guides phagocytes towards the pathogen - they act as chemotaxins grafts „b” have enzymatic activity (proteolytic) - they form so-called convertases (C3 and C5) the only exception to this rule is C2 - it's the other way around o in addition to C proteins, there are also regulatory factors - B, D, H, I - complement components are synthesized in the liver

Answer 322

Opsonisation, Chemotaxis and Osmotic lysis

Answer 323

- C3b encapsulate the pathogen͕ thereby flavouring͟ it - phagocytes have receptors for C3b - opsonization greatly facilitates (makes easier) phagocytosis

Answer 324

- directing leukocytes and phagocytes toward inflammation and facilitating phagocytosis o works on the basis of the chemotaxin concentration gradient - enhances the formation of oxygen radicals - complementary “a” fragment - C3a and C5a - have this function

Answer 325

- proteins C5 - C9 are able to create a channel (hole) in the membrane of a bacterium through which various substances and water can flow in - the bacterium is hypertonic to the surroundings, causing a large amount of water influx and lysis of the bacterium - but this does not work for all bacteria - for example, gram-positive bacteria have such a thick cell membrane that proteins simply do not reach that deep (this is an example of the evolutionary improvement of some bacteria)

Answer 326

- the goal of each individual activation pathway is to create C5b (triggers terminal phase) and C5a (triggers mast cell degranulation) - the difference is in the mechanism of activation and the formation of different convertases

Answer 327

begins with the binding of IgG or IgM to the microbial surface o IgG subclasses are mutually effective in complement initiation - delayed reaction - because we work with antibodies that are in specific immunity - reactions after 1-2 weeks o earlier, if it is a bacterium for which the body has developed immunity and has memory cells - complement antibody C1 binds to the antibody o protein C1 is a complex consisting of C1q, C1r and C1s o needs to bind to at least two Fc portions of Ig since IgG is a monomer, we need at least 2 IgGs per bacterium to initiate activation on the other hand, IgM is a pentamer, so we only need one IgM to start activation = IgM is more efficient o C1q binds to Ig, causing a conformational change and activating C1r and C1s that become active - C1s begin to split C2 and C4 into C2a, C2b, C4a and C4b - C4b and C2a combine into one complex - C4bC2a, a so-called classical C3 convertase - cleaves C3 into C3a and C3b - C3b combines with C4bC2a to form C4bC2aC3b, which is a C5 convertase -> C5b -> terminal phase of complement o lots of C3b stick to the microbial surface = bacterial opsonization

Answer 328

- is essentially the same as the classical route, except that the initiator is not C1 but the MBL protein - MBL is Mannan-Binding Lectin o MBL binds specifically to sugar residues that are typical for microorganisms - as soon as MBL finds the binding site, it joins and starts cleaving C2 and C4 (replacing the C1 function), then activation proceeds as in the classic activation path - it works exactly the same convertase as the classical pathway = C4bC2a

Answer 329

- C3 proteins spontaneously cleave into C3a and C3b - cleaved C3 may associate with factor B and D, which cleaves factor B into Ba and Bb - C3b and Bb combine to form C3bBb, which is a C3 convertase - C3bBb complex has a very short lifetime when it is not attached to the cell membrane o somatic cells have proteins on the surface that can inactivate C3bBb, but bacteria do not have these proteins o Factor P may also bind to C3bBb, which further stabilizes C3bBb - additional C3b is added to C3bBb to form C3bBbC3b, which is an alternative C5 convertase -> terminal complement phase

Answer 330

- the terminal phase is the same for all routes - begins with the complement fragment C5b - C5b adheres C6 and C7 to form C5bC6C7 complex on microbial membrane - C5bC6C7 complex captures one C8 protein and pushes it into the membrane (as an anchor) - 10-16 C9 proteins, are attached to C8 to form a membranolytic complement (MAC) complex in the membrane

Answer 331

- regulation is important to protect the cells themselves from the effects of complement - C1 inhibitor - blocks C1 activation - C3 convertases disintegrate upon interaction with DAF or C4-binding protein - Factor I cleave C3b (using MCP and CR1 membrane proteins or factor H) - CD59 blocks pore formation by binding between C8 and C9

Answer 332

- Hereditary angioedema - C1 inhibitor deficiency o each (though minimal and harmless) stimulus leads to the activation of the entire complement cascade o the classic clinical manifestation is an increase in bradykinin, a vasodilator o due to bradykinin, fluid can leak from the blood vessels into the tissues and cause swelling (especially in RS) - Meningitis o missing terminal components, which means susceptibility to various bacteria, such as Neisseria, that cause meningitis

Answer 333

Inflammation - physiological reaction to damage to the organism - protection against infection, localization of damage and healing - manifestations of inflammation - redness (rubor), swelling (tumor), itching (dolor), temperature increase (calor - local or systemic) and loss of tissue function - acute inflammation- usually resolves without problem and the injured tissue heals - chronic inflammation - pathological, tissue destruction occurs (at to some extent) and replaced by connective tissue - the signal for the development of inflammation comes from degranulated mast cells and phagocytes and substances released from damaged cells o this mix causes increased vascular permeability, increased endothelial adhesion and activation of fibrinolytic, kinin and complement systems - nerve endings (pain) and temperature regulation (pyrogens) become effected

Answer 334

- In the event of prolonged inflammation, antigen-specific mechanisms are activated o dendritic cells + macrophages = "snitches" - into the lymph nodes o antigens from inflammatory sites together with APC travel to lymph nodes and stimulate lymphocyte activation and differentiation o activated Th1s move to the site of inflammation where they can better activate macrophages o Antibody producing B cells help in opsonisation and activation of complement - acute phase proteins are synthesized in the liver at a greater extent of inflammation

Answer 335

- With the activation of inflammatory processes, even the reparative ones are activated - macrophages are responsible for the elimination of damaged cells (phagocytose them) - activation of fibroblastic mechanisms and angiogenesis - If the phagocyte has nothing to bind and destroy, it dies (apoptosis) - tissue regeneration and remodeling o in chronic inflammation fibroblastic mechanisms predominate - instead of functional tissue it will be fibrous

Answer 336

- physiological response of the organism to damage - signs of inflammation - Celsius signs (redness, pain, fever, swelling) + loss of tissue function (functio laesa) - types of inflammation - acute and chronic - signalling molecules that play a role in inflammation - histamine, cytokines (IL-1), prostaglandins, eicosanoids

Answer 337

- contain twenty carbons (their name, Greek - eikosi - twenty) - are derived from fatty acids - most eicosanoids are synthesized from arachidonic acid

Answer 338

- is based on eicosanoic acid (twenty carbons, saturated fatty acid) - arachidonic acid = eicosatetraenoic acid - four double bonds o double bonds in unsaturated fatty acids are unconjugated (they would be conjugated if the single bond was alternated with the double bond regularly) o marking of double bond sites: Δ (deltaͿ system - calculated from COOH, so arachidonic acid would be Δ5,9,11,14 ω (omegaͿ system - calculated from the end, only the first double bond is written, so arachidonic acid would be ω-6

Answer 339

o linoleic acid (C18: 2 ω-6), γ-linolenic acid (C18: 3 ω-6), dihomolinolenic acid (C20: 3 ω-6) , arachidonic acid (C20: 4 ω-6)) o palmitic fatty acid (16 carbons) is synthesized in the body o elongase enzymes can extend fatty acids by two carbons o double bonds are treated by desaturases, but they form a double bond on carbon ω-7 and above ω-1, ω-2, ω-3, ω-4, ω-5, ω-6 acids are all essential (the body cannot produce them)

Answer 340

o when we need it quickly (e.g in inflammation) we need to get it out of that membrane quickly - through phospholipases o phospholipids have a fairly constant structure - glycerol with saturated fatty acid at the 1st position, unsaturated fatty acid at the 2nd position and phosphoric acid at the 3rd position phospholipase A1 cleaves the phospholipid at the 1st position phospholipase A2 cleaves the phospholipid at the 2nd position phospholipase C cleaves the phospholipid at the 3rd position phospholipase D cleaves the phospholipid downstream of the phosphorus atom to form phosphatidic acid o we need phospholipase A2 to release arachidonic acid

Answer 341

- cyclic o prostaglandins (PG) o thromboxane (TX) - linear o leukotriene (LT) o lipoxins (LX) - individual eicosanoids are marked with three letters and number - first PG / TX / LT / LX, then another letter and number which determines the number of double bonds in the molecule (the number of double bonds helps to determine the origin and function of the eicosanoid) o often (not always) eicosanoids with numbers 1 and 3 act exactly in the opposite way to the eicosanoids 2.

Answer 342

- eicosanoids are synthesized from arachidonic acid - enzymes cyclooxygenase (COX) or prostaglandin endoperoxide H synthase (PGHS) are the first enzymes in the synthesis of cyclic eicosanoids - they synthesize prostaglandin H - enzymes lipoxygenase (LOX) enzymes are enzymes that initiate the synthesis of linear eicosanoids Lipoxygenase (LOX) - their first product is hydroperoxy-eicosatetraenoic acid (HPETE) Cyclooxygenase (COX) (very important) - Generally, two are important - COX-1 and COX-2 - COX-1 - constitutively active enzyme, ensures common things, eg regulates blood pressure in glomeruli, mucus production in stomach mucosa - that's why it is called housekeeping enzyme - we need it for normal body function - COX-2 - induced by inflammation

Answer 343

- Large amount of effects - most eicosanoids are mediators of inflammation - they contribute to pain, temperature increase, vasodilatation, redness͙ - prostaglandins- increase body temperature during inflammation and stimulate mucus production in the stomach - thromboxane- stimulates platelets to form blood clots - leukotrienes- causes bronchoconstriction - in addition, there are other versions of eicosanoids that cause the exact opposite (vasoconstriction͕ bronchodilation͙Ϳ

Answer 344

- the oldest way to treat inflammation is by inhibiting COX, eg ibuprofen, aspirin (acetylsalicylic acid), paracetamol - ibuprofen and aspirin are non-selective inhibitors of cyclooxygenases, which means that they inhibit both COX-1 and COX-2 o blocking COX-1 reduces mucus production, which increases the risk of digestion of the gastric mucosa and its bleeding o unlike ibuprofen, aspirin is an irreversible inhibitor and is therefore used in small doses to prevent myocardial infarction - in small because normal cells do synthesize new COX and do not mind aspirin, but platelets do not have a nucleus and are thus permanently effected (until new platelets come) - today there are quite a lot of selective COX-2 inhibitors, they can be identified by reading COXIB somewhere in the name of a drug - non-steroidal anti-inflammatory drugs may cause asthma attacks in susceptible people - also act as antipyretics and analgesics

Answer 345

it blocks COX-2 - at high doses, it is very toxic to the liver (it can easily kill you)

Answer 346

- function through inhibiting phospholipase A2, which prevents arachidonic acid from mobilizing - glucocorticoids and their (more potent) derivatives are used - glucocorticoids stimulate the synthesis of proteins in the nucleus - eg lipocortins that inhibit phospholipase A2 - in addition, glucocorticoids reduce the division of white blood cells and otherwise anti-inflammatory - so they are used with caution

Answer 347

- zafirlukast or montelukast - asthmatic reaction antagonists - leukotrienes cause bronchoconstriction, so blocking their receptors should help o truly helps, but only in a few types of asthma

Answer 348

o exoantigene - foreign substance recognized by the immune system (infectious microorganisms) o autoantigen - antigen from own cells immune system response to this antigen = autoimmune disease (DM 1, myasthenia gravis) o superantigene - exoantigen non-specifically activating lymphocytes independently of their antigen specificity acts like a tsunami - activates the entire immune system o allergen - causes a pathological (allergic) immune response in a susceptible individual, but is not autoimmune - antigens are macromolecules or low molecular weight substances bound to a high molecular weight carrier o Proteins͕ glycoproteins͕ polysaccharides͕ lipoproteins͕ lipids͕ nucleic acids ͙ - they may be soluble or expressed on the cell surface - epitope - part of the antigen that the immune system recognizes - immunocomplexes - antigen-antibody complex

Answer 349

- MHC stands for Major Histocompability Complex o This is a large complex of genes present in vertebrates human MHC is called HLA (Human Leukocyte Antigen) o Molecules named after their features which were first noticed by the MHC researchers - they found that these molecules play a critical role in the compatibility of transplanted organs and their recipients

Answer 350

MHC molecules are glycoproteins that are found on the outside of all vertebrate nucleated cells o Serve to hold randomly selected peptides derived from the cytoplasm of a cell and display this molecule to the immune system which determines if this molecule is normal or not - 5 MHC species are currently known, but MHC IV and V are not well known and probably not important o MHC I is present on all nucleated cells and enables cell status control o MHC II is on antigen-presenting cells and calls lymphocytes for help o MHC III does not functionally belong to the same group as MHC I and II, instead they are proteins which are secreted into the blood and help with different physiological processes Part of MHC III are some complement components, stress proteins and the cytokine TNF

Answer 351

- MHC molecules are encoded at 6p21 o these genes are codominant and show high polymorphism, which considerably complicates organ donation There are tens to hundreds of allelic forms in the population At the same time, codominance is manifested, so both legacy alleles contribute to the outcome o genes for MHC I - HLA-A, HLA-B, HLA-C and less polymorphic HLA-E, HLA-F, HLA-G o genes for MHC II - HLA-DR (highest polymorphism), HLA-DP, HLA-DM, HLA-DQ, (and their subgroups, which are not that important) - more frequent occurrence of specific HLA alleles is in most cases associated with certain diseases => eg Bechterew's disease (about 98% of affected patients have the HLA-B27 allele => this disease affects and gradually immobilizes spine and limb joints)

Answer 352

- on all nucleated cells of the body (some more and some less, but all are nucleated) - select random 8-10 amino acid-long endogenous peptides from the cytosol of the cell, bind them, and expose them o MHC I is unstable without a bound peptide and degrades rapidly o cells of the immune system (cytotoxic T and NK) check the exposed peptides, and if they conclude that the peptide is of foreign origin (such as viral or tumorous), they destroy the cell - cells with receptors for MHC I o cytotoxic T lymphocytes - receptor CD8 o natural killers (NK) ʹ activation receptors KAR (MICA, MICB, ULBP) and inhibitory receptors KIR (HLA-C, HLA-G)

Answer 353

- consists of two polypeptide chains - α and β o α is longer, crosses the membrane and contains three domains - α1͕ α2 a α3 o β is smaller (microglobulin), is called β2-m, noncovalently associated with α͕ is non-polymorphic and is coded outside HLA (on the 15. chromosome) - the walls of the groove for peptide placement are α1 and α2 and its bottom is made of 8 antiparallel β chains - the whole glycoprotein is anchored to the membrane by one unit

Answer 354

- two MHC I groups - classical and non-classical (differ in polymorphism) - classical MHC I - HLA-A, HLA-B, HLA-C o HLA-A a HLA-B are significantly polymorphic (ц ϳρϬ allelesͿ, HLA-C slightly less o all HLA-C variants bind to inhibitory NK receptors and thereby inhibit their cytotoxic activity - non-classical MHC I - HLA-E, HLA-F, HLA-G o their expression on cells is variable - there may be many, few, or none on the cells o HLA-G is found only on trophoblasts - they inhibit NK cells protects the cells of the trophoblast (= placenta) from damage by the mother's immune system o Non-classical MHC I proteins include molecules with the abbreviations MIC, ULBP and CD1 MIC - on epithelial cells, they are expressed under stress, they activate NK cells ULBP - they are expressed under stress, they activate NK cells CD1 - not encoded in HLA, present antigens of non-protein character (eg. Glycolipids) - the trophoblast cells have HLA-C, HLA-E and HLA-G on them

Answer 355

- MHC molecules are transported to ER during synthesis -> in the ER lumen both MHC chains ;α and B2-m) are folded together, creating a peptide binding site o MHC I are unstable unless a peptide is attached to them - meanwhile, the proteasome cleaves the ubiquitin-labeled cytoplasmic proteins and the resulting small peptides are transferred to RER by the TAP1 and TAP2 proteins (Transporters Associated with antigen Processing) - only when the peptide is bound to the MHC molecule, does the entire complex travel from the ER through Golgi to the cell surface - upon disconnection of the peptide MHC I changes its conformation͕ β2-m dissociates and α chain is internalized into the cell and degraded

Answer 356

- MHC I may present peptides from extracellular sources - cross-presentation - the material that accumulates on the cell surface receptors is endocytosed and reaches the endosomes - where it can be partially (but not completely) degraded and transported to the cytoplasm where it is cleaved in proteasomes and its peptides then transported to the ER - another way how extracellular peptides can reach MHC I is the fusion of late phagosomes (containing peptide fragments) with ER - Cross-presentation is most effective in dendritic cells

Answer 357

- not everywhere, only in antigen-presenting cells (APC - monocytes, macrophages, B lymphocytes...Ϳ - present exogenous peptides (from foreign organisms) to the membrane to which T lymphocytes react (with CD4 receptor)

Answer 358

- they are heterodimers composed of one α and one β chain o both chains are glycoproteins o both chains have an external, linking, transmembrane and cytoplasmic region o both chains are divided into two parts, so we have α1͕ α2͕ β1 a β2 α1 and β1 are variable, α2 and β2 are constant o both chains are non-covalently bound via the interaction with other external domains - inside the cell, the chains are synthesized separately, then they are associated with the third chain γ o when this complex reaches the plasma membrane͕ the γ-chain is dissociated and only the two-chain complex is exposed to the membrane - MHC II holds to the membrane by two units/legs - The peptide binding site is open (the binding site is not ͞bounded͟ so that even longer peptides that may protrude beyond its edges may bind to it) and present peptides of 15 or more amino acids in length

Answer 359

- The beginning is similar to MHC I - chains are synthesized separately and folded together in RER - but here the MHC II joins the so-called invariant chain (abbreviation Ii)- thus creating a trimer o Ii blocks the MHC II binding site - prevents any cellular peptide from entering the antigen site - the resulting trimmer is sent to GA, packed there in a secretory vesicle and sent to the cytoplasm - in the case of phagocytosis of the pathogen, the pathogen is destroyed in the endosome, which then fuses with the secretory vesicle (in which it is MHC II) - after this coupling, Ii degrades to a smaller peptide (the so-called CLIP), which is removed to free up space for the exogenous peptide - the MHC II with the pathogen then slides out of the membrane and waits for the T cell

Answer 360

- a place where B and T lymphocytes (bone marrow, thymus) mature B-lymphocytes - Bone marrow T-lymphocytes - Thymus

Answer 361

- place where mature B and T lymphocytes are waiting for activation they are divided according to their encapsulation and localization encapsulated and non-mucosal organs - lymph nodes, spleen unencapsulated and inside the mucosa of the organs = MALT (mucosa-associated lymphoid tissue) x tonsils, appendix, Peyer plates x can be further divided into GALT (gut, including Peyer plates), BALT (bronchus), SALT (skin)͙

Answer 362

- reticular connective tissue - consists of reticular cells (fibroblasts) and reticular fibers (collagen III) o Reticular cells - produce intercellular matter, cytokines, and adhesion molecules - Dense lymphoid tissue - high lymphoid cell content - Loose lymphoid tissue - - large sinuses for lymph and lymphocyte flow

Answer 363

lymphatic follicles

Answer 364

- monochromatic, contains a large number of B lymphocytes these follicles are converted to secondary ones when antigen is presented to lymphocytes and their proliferation begins

Answer 365

- consists of a central lighter area (germinal center) surrounded by a dark lymphocytic mantle Mantle zoneʹ mature B-lymphocytes are activated in the mantle zone by antigens presented to them by follicular dendritic cells (FDC) - activated lymphocytes move to the germinal centre where they are selected and subsequently proliferated germinal centre - can be further subdivided into a lighter and darker part (the difference in shade is slight), but both are lighter than the mantle zone around x in the lighter part of germinal centre, B-lymphocytes are selected according to their affinity of their antibodies to the antigen (these lymphocytes become so called centroblasts) ї the selected lymphocytes move to the darker part of the germinal centre x in the darker part of the germinal centre, activated B cells proliferate with the help of Th lymphocytes o so-called clonal expansion and also rearrangement of variable parts of antibody chains ;somatic hypermutationͿ ї centrocytes are formed - they must be activated secondarily and become a plasma or memory cell

Answer 366

o activated B-lymphocytes ;ͣcentroblasts ͞Ϳ - proliferate and at the same time undergo mutations of V-segment genes o centrocytes - are the result of centroblast multiplication and are subject to selection o APC follicular dendritic cells, macrophages o Th- lymphocytes- help B cells proliferate o plasma cells ʹ only a little

Answer 367

- lies next to the B-dependent region and is populated by T-lymphocytes - besides T lymphocytes it contains so-called interdigitating dendritic cells, which are professional APCs, which interact with naive T lymphocytes - there are high endothelial venules, through which lymphocytes pass into tissues o they return to the blood through the lymphatic vessels - naïve T-lymphocytes preferably return to the T-dependent region, where they may encounter an antigen - effector and memory cells travel to different places than the lymphatic organs o have so-called homing receptors on their surface, which interact with specific ligands on the endothelium and are able to direct (hence the name homing) these cells where they need

Answer 368

- primary (central) lymphatic organs - thymus and bone marrow o a place where primary lymphocyte differentiation occurs - naive B and T cells - secondary (peripheral) lymphatic organs - spleen, lymph nodes, tonsils, o instead of an immune response

Answer 369

- it is the primary lymphoid organ of the T-lymphocyte system - unlike secondary lymphatic organs, it is not formed by reticular connective tissue but by reticular epithelium, which is already inhabited in the early fetal period by precursors of the T-cell line - mature bone marrow lymphocyte precursors colonize the thymus and undergo terminal differentiation and proliferation

Answer 370

o T-cell maturation involves positive and negative selection o positive selection - if the T lymphocyte does not recognize the pathological antigen, it is killed by apoptosis o negative selection - if the T lymphocyte misidentifies the normal body antigen as pathological and attacks it, it is killed by apoptosis o In total, about 95% of T lymphocytes are eliminated by these mechanisms

Answer 371

o The thymus itself consists of two lobes connected by the connective tissue o the surface of the organ is soft and elastic and is covered by a thin fibrous membrane that penetrates inside the thymus in the form of septum o septa divide the lobes into smaller lobules - each lobulus has a cortex (lobe at the edges, darker) and medulla (inside lobe, lighter) o cortex - where the first developmental steps and positive selection of T-lymphocytes occur nurse cells - special epithelial cells in the thymus cortex, which are essential for proper development of T-lymphocytes o medulla - site of negative selection of T-lymphocytes epithelial cells in the pulp cluster into so-called Hassal bodies, whose meaning is not yet fully understood x cells in the center of Hassal bodies undergo keratinization

Answer 372

o cortex - there are juvenile, developing T-lymphocytes in the cortex, which should be protected from circulating antigens, so we have a barrier in the form of cortical epithelial cells, endothelial continuous capillaries and their fused basal laminations o medulla - we only have immunocompetent T lymphocytes in the pulp, so there is no need for a barrier free access between blood and thymus pulp is provided by special cortico-medullary venules through which immunocompetent T-lymphocytes go to T-dependent areas of secondary lymphatic organs - thymus reaches its maximum size during childhood and gradual involution occurs from puberty to age 50 o however, small residues of thymic tissue is preserved, suggesting continuous T-cell maturation throughout life o the weight of the whole thymus decreases during involution, but the cortex is most affected, while the marrow is preserved as a thin continuous belt

Answer 373

- a secondary lymphoid organ where mature B and T lymphocytes accumulate and await activation - the surface of the node is covered by a capsule of rigid collagen tissue, fibrous trabeculae protrude inwards - several afferent lymphatic vessels flow into the lymph node and one large efferent lymphatic vessel flows o the place where the efferent lymphatic vessel leaves the lymph node is called the hilus o blood also flows through the hilus - the interior of the node can be divided into 3 parts - cortex, paracortex and medulla o cortex - contains primary and secondary lymphatic follicles B-dependent region plus follicular dendritic cells there is a subcapsular sinus between the cortex and the capsule = an enlarged area that is lined with a discontinuous wall that can be penetrated by lymphocytes - the sinus serves to slow down the flow of lymph (this will make filtration more efficient) o paracortex - T-dependent region, contains high endothelial venules o medulla - medullary sinus, blood and lymph capillaries, plasma cells͕͙

Answer 374

- its function is to filter blood, remove old and damaged red blood cells and also plays a role in lymphocyte activation - similar to nodules but without lymphatic vessels

Answer 375

white pulp - a system of lymphatic follicles in which blood-born antigens can trigger an immune response consists of three components - PALS (periarteriole lymphatic sheath), lymphatic follicles and marginal zone PALS is a layer of lymphatic tissue surrounding all arteries in the spleen x there are mainly T lymphocytes lymphatic follicles - lymph node nodes linked to PALS x In addition to B cells, they also contain follicular dendritic cells marginal zone - the external zone of the follicle forming the border between the white and red pulp

Answer 376

- Captures and destroys old and damaged red blood cells consists of spleen cords ("Billroth cords"), with venous sinuses running inside blood does not travel from the arteries directly into the veins, but flows into the extravasal space Many macrophages reside in the tissue of red pulps, which phagocytose defective red blood cells

Answer 377

- there is a capsule on the surface from which the fibrous trabeculae protrude - in the hilus, it opens into the spleen of the artery, which gradually branches and brings blood to the red pulp, from which it is drained by veins ending in the hilus and coming out of it o a. lienalis, enters the hilus, passes through the capsule and then branches into the fibrous trabecula in the form of aa. trabeculares o aa. trabeculares exit the trabecula and continue to pulps = aa. Centrales o aa. centrales are encapsulated with a layer of lymph tissue (PALS) and are usually also surrounded by lymph nodes further branching and thus emerging from the white pulp to red ʹ into extravasal space ʹ into sinusoids

Answer 378

o filtration occurs in sinuses- they do not have a continuous endothelium, so they can enter erythrocytes (however, they must be sufficiently flexible - old erythrocytes are not elastic, so they do not stretch through the endothelium and macrophages, which occur in the vicinity of sinus) o from the sinus, the blood continues through the post-capillary veins into the medullary veins, which converge into the fibrous trabecula = trabecular vein, which eventually merge to form the v. lienalis (which then flows into the v. portae) o veins and arteries run in trabeculae side by side - they just carry blood in opposite directions

Answer 379

- organized lymphatic tissue in the lamina propria of many mucous membranes - is based on reticular connective tissue, lymph nodes (B-dependent zones) and between them T-dependent regions - some components of MALT are separate organs or macroscopic structures- for example tonsils (palatina, pharyngea, lingualis, tubaria) and Peyer's plates in the intestinal wall (mainly ileum) - the epithelium is a stratified squamous non-keratinized or stratified-row cylindrical

Answer 380

- components of antigen-specific immune responses - main function - production of immunoglobulins - carry the B-cell receptor (BCR), which is a surface immunoglobulin (antibody permanently attached to the cell membrane of a B-cell) and associated molecules - forms 5-15% of circulating white cells

Answer 381

- BCR consists of surface immunoglobulin and other associated proteins mainly Igα and Igβ the main component of the receptor is a surface immunoglobulin, which has a standard structure => 2 light and 2 heavy chains it is a transmembrane molecule = heavy chains are anchored in the membrane, light chains look away most often belong to the IgD or IgM class molecules associated with BCR - CD Igα and CD Igβ or CD79A and CD79B 􏰀 they are kinases involved in triggering signalling cascades of other molecules in the BCR neighbourhood 􏰀 CD 21 - or CR2 􏰆 A complement receptor that enhances the signal from BCR 􏰆 it can bind fragments of complement components -> eg C3b, thereby regulating the immune response 􏰀 CD 19 - this receptor is found only on B cells and is therefore a useful marker of B cells

Answer 382

- localization of genes for chains o all heavy chains - chromosome 14 o light kappa chain - chromosome 2 o light lambda chain - chromosome 22 - the single chain genes that make up the antibody consist of several parts or segments o heavy chain gene for the variable part has 3 segments that eventually join together - V (variability), D (diversity) and J (joining) the segments are drawn one at a time, but only for simplicity - in fact there are many V, D and J segments in sequence the gene for the constant part has 5 segments from which one is chosen, this determines the type of antibody types of constant parts of heavy chains - 􏰈 IgM δ IgD γ IgG IgE α IgA o light chain 􏰂 gene for variable part has 2 segments that join together - V (variability) and J (joining) 􏰂 there are two types of constant parts of light chains: lambda and kappa but each is on a different chromosome o all heavy chains - chromosome 14 o light 􏰆 􏰀kappa􏰁 chain - chromosome 2 o light 􏰇 􏰀lambda􏰁 chain - chromosome 22 - the single chain genes that make up the antibody consist of several parts or segments

Answer 383

- it is the first step in the development of B-lymphocyte - it takes place in the nucleus at the DNA level o After this process, the B-lymphocyte progenitor becomes a B-lymphocyte precursor - basically, one of the many V segments, one of the many D segments, and one of the many J segments is randomly selected, and the three random segments merge together while all the others are chipped o the so-called D-J rearrangement first - a certain segment between random D and J segments is selected, and is cut out o V-DJ rearrangement occurs - the segment is selected again, this time between the V segment and the newly created D-J segment, which is then cut and the remaining parts are joined - gene segment rearrangement occurs on both chromosomes 14 simultaneously and the whole process is completely random - the aim is to obtain as many original (unique) antibodies as each will have a different affinity for individual antigens and as a result will cover as wide a spectrum of antigens as possible o we have about 100 V-segment, 50 D-segment and 9 J-segment versions, bringing together 45,000 unique combinations (100 * 50 * 9)

Answer 384

if the rearrangement on one chromosome is active (successful transcription takes place) then the rearrangement on the other chromosome is stopped (it is not entirely clear why, but it is happening)

Answer 385

- second step of B-cell development - B-cell precursor becomes immature B-cell - it is the same process as for somatic heavy chain recombination, but here we have only V and J segments, so the number of original light chains will be considerably smaller -as with the heavy chain, the rearrangement takes place on two chromosomes simultaneously - if during any somatic recombination process an antibody is produced that responds to normal body cells, the B-lymphocyte producing these antibodies is destroyed by apoptosis o control of B cells is not so strict - if by chance an autoreactive B cell escapes, usually nothing happens because it would need a similar autoreactive T cell to activate, and they are controlled much more strictly

Answer 386

- refers to the constant part of the heavy chain - while the process of somatic recombination is in progress, the constant part of the heavy chain must still be selected to determine the type of antibody - either IgM and IgD are always selected o however, it does not affect its affinity for antigens - it only plays a role in what cells it will interact with (eg mast cells have an Fc receptor for the IgE C region)

Answer 387

- once the B-lymphocyte has its finished antibody, it leaves the blood marrow through the lymphatic system and settles in the follicle of some lymph node - when nested, it is called mature B-lymphocyte

Answer 388

- in the lymph node, a mature B-cell waits until it encounters a call for activation from a follicular dendritic cell (FDC) - once activated, the B-cell travels to the germinal center of the lymphatic follicle, where it becomes a centroblast and starts to proliferate very quickly o this process is called clonal (one cell as another) expansion - during proliferation, however, there are other changes at the DNA level called somatic hypermutations

Answer 389

- it takes place on variable parts of both chains - it concerns V, D and J segments - after several rounds of proliferation, the centroblasts will express the enzyme AID, which will start random point mutations in the DNA in the V, D and J segments o these changes will lead to a changes in antibodies - to increase or decrease their affinity for the antigen that initiated the activation of mature B-lymphocytes - if the changes in the variable part are negative (= if the affinity of the antibody for the antigen decreased), the B- lymphocyte undergoes apoptosis - if the changes in the variable part are positive (= if the affinity of the antibody for the antigen increased), then the B- lymphocyte lives on and becomes a centrocyte

Answer 390

- refers to the constant part of the heavy chain - after somatic hypermutation, the B-cell may be instructed to change the type of antibodies it produces o Thus, instead of IgM and IgD, the B-cell will begin to produce IgG, IgE or IgA - the aim is to produce the type of antibody that is most effective against the pathogen to which the B-cell responds o If the pathogen has been found in the pancreas or lymph nodes, the immune system will produce IFN-γ which instructs the B-lymphocyte to produce IgG, the most common antibody o If the pathogen was found in mucosal tissue, TGF-β and IgA􏰉 an antibody that can penetrate into the mucosal tissue, will be produced and will therefore be most effective against this type of pathogen o however, if it is a parasitic infection, eosinophils, basophils and mast cells will secrete IL-4, signaling B- lymphocytes to start producing IgE, an antibody directed to parasites - at the end of B-cell development it may become a plasma cell that circulates in the blood and produces antibodies, or a memory cell that is important for immune memory

Answer 391

Summary - B-lymphocyte progenitor-> somatic heavy chain recombination -> B-cell precursor -> somatic light chain recombination -> mature B-lymphocyte-> lymph node leaving the bone marrow + nesting in the lymph node-> mature B-lymphocyte -> activation + germinal migration -> centroblast -> proliferation + somatic hypermutation -> centrocyte -> isotype switching -> plasma cell or memory cell

Answer 392

- components of antigen-specific immune responses - have different subtype functions

Answer 393

- consists of two parts - the antigen recognition module and the protein complex o antigen recognition module- is similar to an antibody has 2 transmembrane chains - α β or less frequently γ δ the heavy chain equivalent is a beta chain - having V, D, and J regions the light chain equivalent is the alpha chain - it has V and J regions cooperates with CD4, CD8 co-receptors in antigen recognition -without them the receptor is inoperative 􏰅 CD4 - helps bind to MHC II 􏰅 CD8 - helps bind to MHC I o complex protein - CD3 complex it is a transmembrane system through which the signal from the TCR is transmitted to the cell - somatic recombination is activated by the RAG gene o the same process as B-lymphocytes

Answer 394

- TCR is the first step in the development of a T-lymphocyte progenitor (pro-T) to become a T-lymphocyte precursor (pre-T) - the next step is to create CD4 and CD8 co-receptors - the so-called double-positive T lymphocyte or CD4 + / CD8 + T lymphocyte o adult T cell has only one of these receptors, depending on its function CD4+ T- lymphocyte = Th lymphocyte = helper, forms cytokines for activation and regulation of immune response CD8+ T- lymphocyte = Tc lymphocyte = cytotoxic, killing cells infected by intracellular parasites

Answer 395

- positive selection - double-positive T lymphocyte must meet MHC molecule in thymus for its differentiation o If it meets MHC I - it binds to it by its CD8 receptor and CD4 disappears = it becomes Tc o if it meets MHC II - it binds to it by its CD4 receptor and CD8 disappears = it becomes Th - negative selection - immature Tc or Th lymphocyte cannot be directly discharged into the blood - must be checked to ensure that it is not autoreactive o dendritic cells present somatic antigens in the thymus - if an immature T lymphocyte binds to one of them, it is immediately killed by apoptosis - T cells that have undergone both positive and negative selection are now mature and leave the thymus

Answer 396

- pro-T -> TCR synthesis -> pre-T -> CD4 and CD8 synthesis-> double positive T lymphocyte-> positive selection-> immature Tc / Th -> negative selection-> mature Tc / Th -> travel to the blood and settle in peripheral lymphatic organs - pre-T is sometimes also referred to as a double negative T-cell (because it has neither CD4 nor CD8)

Answer 397

T-lymphocytes - have a role in the elimination of cells infected with intracellular parasites and in the regulation of B-cell development - there are minimal morphological differences between T and B lymphocytes - we distinguish them on the basis of specific surface CDs o B lymphocytes - CD19, CD20 o T lymphocytes - CD3, CD4, CD5, CD8

Answer 398

- Th lymphocytes are the start-ups - they start and regulate the other components of the immune response - cell coming from the thymus into the lymph node is inactive and needs several signals to start functioning properly o antigen recognition - APC presenting antigen on MHC II o costimulation - CD28 receptor on the surface of Th lymphocytes must also be stimulated for activation ligands of this receptor are CD80 and CD86 on the surface of APC without costimulation, Th-lymphocyte gets into a state called anergy - it recognizes the antigen, but does nothing o presence of cytokines - first two signals the Th-lymphocyte needs for activation, cytokines regulate what exactly will be activated IL-12 -> Th1 IL-4 -> Th2 IL-17, IL-22 -> Th17 - there are several types of activated Th lymphocytes - the most important are Th1 and Th2

Answer 399

- promote cellular immunity - activates cytotoxic T-lymphocytes and macrophages o important to defend against intracellular infections - IL-12 from macrophages increases Th1 production - promote the production of IgG antibodies (to improve opsonisation and complement activation) - important cytokines o IL-2 - comes from Th1, but a bit from Th2 stimulates the growth of T-lymphocytes activates B-lymphocytes and NK cells o IFN-γ activates macrophages and improves their phagocytosis capabilities activates Th1 production and inhibits Th2 production stimulates the production of MHC I and MHC II

Answer 400

- promote molecular immunity - activate B-lymphocytes and stimulate antibody production, mainly IgE and IgA - important cytokines o IL-4 - a major Th2 cytokine activates Th2 production and inhibits Th1 production Supports IgE production - important for defence against parasites and allergies o IL-5 - activates eosinophils supports IgA production - important for mucosal immunity against intestinal bacteria o IL-10 - an anti-inflammatory cytokine inhibits Th1 production has no inflammatory effect - „bystander help”- Th2 can deliver costimulatory signal to B cells by connecting Th2 CD40L with B cell CD40 o Useful if B-lymphocytes recognizes the antigen but has not received a costimulatory signal

Answer 401

- important in the defence against intestinal bacteria and helps in infections with intracellular pathogens by producing IL- 17, which has similar effects to IFN-γ

Answer 402

- something between NK and T lymphocytes - recognize non-classical MHC molecules, CD1 and others

Answer 403

- their main role is to find and destroy tumor cells and virus-infected cells - recognize antigens presented on MHC I o Since MHC I is found in all nucleated cells, Tc-lymphocytes have many potential APC - mechanisms of cell killing o perforin-granzin system same as for NK cells - Tc releases perforins and granzymes into the intercellular space perforins create channels in the membrane of the target cell through which granzymes can enter, once within the cytoplasm of the target cell, granzymes activate caspases and trigger apoptosis o Fas-Fas ligand interaction Tc have an important structure called fas ligand on their surface Fas ligand binds to Fas, which is CD95, on the surface of many cells this binding activates caspases in the cytoplasm of the target cell and thus leads to apoptosis

Answer 404

- they are not perfectly understood - they carry CD4, CD3 and especially CD25, which is their distinguishing label - suppresses inflammatory response - produce anti-inflammatory cytokines IL-10 and TGF-β

Answer 405

- main function - kills human cancer cells + virus-infected cells + produce IFN-γ to activate macrophages - kills infected cells - some MHC I viruses bypass the mechanism by simply blocking the production of MHC I o no molecules on display = no help from T lymphocytes o NK cells solve this problem by killing all cells having a reduced number of MHC I on their surface - NK cells are lymphocytes - although they belong to innate immunity, they originate from the same developmental line as B and T lymphocytes - carry numerous granules with proteins such as perforin and granzymes in their cytoplasm o perforin - creates a channel on the membrane through which the granzymes can reach the target cell o granzyme - a group of serine proteases that trigger apoptosis by activating caspases

Answer 406

o it is the cooperation of innate and adaptive immunity - antibodies (adaptive immunity) envelop the pathogen and NK cells or eosinophils (innate immunity) destroy it, other than phagocytosis o NK cells bind to IgG and destroy pathogen-infected cells o Eosinophils bind to IgE and destroy pathogens, especially large parasites (which are too large for phagocytosis)

Answer 407

o CD16 - binds to Fc part of IgG = important for ADCC o CD56

Answer 408

immunoglobulins and antibodies have many unique functions: o participate directly in protection against infection o also help with other mechanisms → phagocytosis, complement activation o activate inflammatory cells B-lymphocytes primarily differentiate into plasma cells (they form Ig), T-lymphocytes and phagocytes are also affected B-lymphocytes present antigen

Answer 409

B-lymphocytes: the main feature of B-lymphocytes the production of immunoglobulins (respectively their differentiation into plasma cells and subsequent formation of Ig)) during B-cell ontogenesis, individual developmental stages can be identified by progressive rearrangement of the Ig heavy and light chain genes along with special changes in the cell membrane phenotype (changes related to CD molecules and BCR) B-cell maturation alone depends on bone marrow stromal cells and IL-7 produced by them approximately 15% of peripheral leukocytes are B-lymphocytes molecules on the surface of B cells - CD20, CD19, CD21 CD34 - on the surface of stem cells

Answer 410

each B cell can only produce one specific antibody → all its antigen receptors have the same specificity after the B-lymphocyte meets the antigen, clonal selection and expansion occur o selection = lymphocytes (with specific receptors) are selected to participate in the immune response o selection is followed by expansion = these particular lymphocytes proliferate → rapid increase in the number of B- and T-lymphocytes that can recognize antigen However, B cells are under the regulatory control of T cells o activated T-lymphocytes and NK cells produce eg IL-22 (inhibits Th2, which commonly supports B-lymphocytes) o immune response is also generally regulated by mutual interactions of Th1 and Th2 lymphocytes → both Th species inhibit each other by their products Th1 produce IL-2, INF-γ͕ IL-12 Th2 produce IL-4, IL-5, IL-6, IL-10

Answer 411

B-cell differentiation (antigen-independent): takes place in the bone marrow - a B-lymphocyte progenitor is formed, which gradually transforms into an immature lymphocyte and leaves the bone marrow (further differentiation takes place in secondary lymphatic organs and is dependent on the antigen) changes the lymphocyte undergoes: o morphological changes (lymphoblast, mature lymphocyte, plasma cell) o changes in membrane conetent o rearrangement of gene segments encoding antigen for B-cell antigen (BCR) → same mechanism as for TCR (V, D, J recombination)

Answer 412

random combinations V (D) J pairing of heavy and light chains mutations of VH, VL (variable strands) o even without mutationsi > 107 different clones model of "selection in ready-made shop͞ the principle of the "anticipatory" system

Answer 413

antigenic stimulation takes place in secondary lymphoid organs (response to most antigens requires cooperation with T- lymphocytes) o activation=> proceeds by direct binding to antigen and also by T lymphocytes (cell contact / cytokines) → primary and secondary antibody response to increase the likelihood that lymphocytes will encounter specific antigens, they must migrate across the body (lymphocytes spend about 30 minutes in the blood within one cycle) o The immune response against antigens located in the blood usually starts in the spleen o The response against microorganisms in the tissues starts in the local lymph nodes most pathogens enter the body by inhalation or ingestion => by entering through mucous surfaces activate MALT cells

Answer 414

lymphocytes are activated by antigens → they bind non-covalently to a specific part of the antigen = epitope o recognize epitope by BCR ---activation---- proliferationʹ--- clone formation o the epitope is recognized by its shape → completes the shape of the antibody the specific site of an antibody that binds an antigen is the complementarity-determining region = CDR Small antigen binding site can be a pocket, scratch, wavy surface antibodies / BCR exceptionally recognize continuous epitope sequence → usually recognize discontinuous epitopes o antigenicity ability to act as an antigen → stability of the antigen structure is important for it - denaturation / disruption of binding decreases antigenicity (there are exceptions where the disruption of the bonds reveals the epitope and has completely the opposite consequences) most responses are made up of many different B cell clones = polyclonal o humoral response in vivo is normally strongly polyclonal ("antiserum") → it means that different B-lymphocytes are activated so that different Igs are produced o monoclonal antibodies means that the production of a particular type of antibody predominates and the production of others is inhibited this may occur in some pathological conditions -> chronic inflammatory stimulation, in a plasma cell tumor (myeloma)͙ polyclonal antibodies are produced by activation of several B-cell clones → unlike monoclonal antibodies they are not identical and act on different parts of antigen ->mosaic of determinants (epitope cluster)

Answer 415

CpG motifs (single-stranded DNA molecules that act as PAMPs) can stimulate B-lymphocytes directly (also adjuvant properties = a substance that enhances the immune response against an antigen) epitope spreading (the immune system is stimulated by one epitope; other epitopes of the antigen may be bound to the response - eg the production of autoantibodies) cryptic epitopesʹ they are actually hidden epitopes (they are presented only after APC stimulation with pro-inflammatory cytokines -MBP)

Answer 416

immunogenicity = ability to call for an immune response → requirements: o Foreignnessʹ only foreign molecules are immunogenic o Molecular size immunogenic: molecules <10 kD (weak or not at all), the strongest are Ag> 100 kD non-immunogenic: extremely small molecules (AA, m-carbohydrates) o chemical complexity Æ immunogenicity increases with chemical complexity (simple synthetic peptides = weak immunogens, aromatic AA = more immunogenic) o stability

Answer 417

o drift = point mutations : minor change in antigenic characteristics the subtypes formed are the cause of recurring minor epidemics → it allows reinfection of people who have already had the disease mutations represent a problem for memory cells (if drift is not possible, infection in the secondary immune response is likely to be suppressed before it can manifest) o shift = genetic recombination between viruses (more severe) → a practically new type of virus is created that is responsible for large pandemics antigenic shift causes phenotype change an example is the influenza pandemic

Answer 418

different types of B cells form different types of antibodies we distinguish between B1 a B2 lymphocytes: o B1 during B-cell ontogenesis arise first most of them express CD5 trait, adhesive and signal membrane molecules they are the source of so-called natural IgM antibodies are often polyreactive (eg they recognize several different antigens, often including common pathogens and autoantigens - similar to mitogens) natural antibodies have a relatively low affinity o B2 are the majority of the B-cell population do not have the CD5 character mature B2 cells simultaneously express IgM and IgD antibodies before contact with Ag they become memory cells after activation → they usually start to express IgG, IgA, or IgE as their BCR when B2 cells in germinal centers encounter antigen → isotype switching → IgG, IgA, or IgE production → somatic hypermutation → plasma cells in secondary lymph. tissue generally live short - half-life only a few days, only some plasma cells survive for weeks (BM)

Answer 419

T independent antigens = TI → are specific antigens that are able to induce antibody production without cooperation with Th First line of defence against surface polymers of microorganisms activation activates intensive "cross-linking" of membrane Ig, which replaces auxiliary signals => no need for contact with Th → cytokines from T and NK cells are sufficient there is no affinity maturation and there is no immunological memory these antigens are divided into two groups: o TI-1 antigens bind at different concentrations to different BCR receptors, resulting in polyclonal BCR activation TI-1 = e.g bacterial lipopolysaccharide low-affinity IgM antibodies are produced after B-cell activation TI-1 are similar to plant lectins or bacterial superantigens - activators of T-lymphocytes o TI-2 antigens are polymers, repetitive structures typical of cell walls of encapsulated bacteria (Pneumococci) or polymeric proteins (flagellin - several subunits of bacteria) - repetitive structures (epitopes) react with multiple BCRs, intensively aggregate BCRs and activate mature B- lymphocytes

Answer 420

only mature B cells are able to react with T1 antigens immature B-lymphocytes are anergized (= functionally inhibited) there is a need for a cytokine help (IL- 2, IL-3, IFN gamma),

Answer 421

T-dependent antigens: the response to most antigens requires cooperation with T lymphocytes characteristics: primary and secondary immune responses o these two phases can be separated (low dose of antigen, intervals between doses) or they can be continuous (naturalinfection) the result is memory cells, high affinity antibodies

Answer 422

3-4 days after immunization firstly stimulation of B-lymphocytes by BCR, then stimulation of Th (→ Th2) by APC (MHC + protein) o Th2 produce cytokines → B-cell costimulation → development of plasma cells and antibodies (part of B-cells differentiate into memory cells that trigger a secondary immune response) activation results in the formation of low affinity IgM antibodies o IgM immunocomplexes and antigen are stored on the surface of follicular dendritic cells (FDCs))

Answer 423

conditions: o recognition of antigens on FDCs in primary lymphatic follicles o signals from Th lymphocytes affinity maturation in secondary lymphatic follicles (specifically in germinal centers) => affinity maturation includes somatic hypermutation and clonal selection o only B-lymphocytes with very high affinity survive (others die) affinity maturation result => affinity of antibodies is 4-6 orders higher than in IgM primary response subsequently, isotype switching occurs -> constant region change of the antibody o isotype switching regulation: IL-4 ї IgE, IgG1, inhibitory IgG2 IFN-γ ї IgG2a, IgG3 TGF-β ї IgG2b, IgA IL-10 ї IgA secondary immune response results in antibodies with high affinity, antibodies with different effector function (complement activation, FcR function), memory cells

Answer 424

Antibodies: immune protection by antibodies: o neutralization: antibodies can neutralize the activity of toxins, viruses, other microorganisms mechanisms: binding to critical epitopes - preventing cell adhesion or cell entry o complement activation, opsonisation classical way of complement activation: IgM or IgG → C1 → formation of C3b͙ o Cytotoxicity caused by antibodies NK cells can cause -> IgG-mediated antibody-dependent cytotoxicity (ADCC) IgE-dependent cytotoxicity macrophages, eosinophils and platelets are involved in cytotoxic mechanisms if the target cell is too large for phagocytosis → perforins, granzymes, or sometimes reactive oxygen metabolites are used

Answer 425

B-lymphocyte binds via BCR antigen → phagocytosis → B-lymphocyte Ag processes and exposes it on its surface to MHC II complex→ MHC II with peptide is recognized by Th

Answer 426

Regulation of immune system function: an effective immune response eliminates the antigen and returns to basal level some other mechanisms initially tune the activity, then attenuate the activity IgG itself can turn off the response to the appropriate antigen (negative feedback) immunocomplexes containing the relevant antigen → the result is the transfer of the inhibitory signal to the B-cell nucleus

Answer 427

Edman degradation - the whole method is based on the marking of the N-terminal amino acid and its subsequent cleavage from the rest of the chain o other methods (chromatography, electrophoresis, etc.) determine which amino acid we actually cleaved - however, this procedure is limited to the length of the peptide chain - the maximum useful length is about 30 amino acids Mass spectrometry - a technique that analyses and divides samples (in biochemistry proteins) according to their charge-to-weight ratio - there is a database full of known proteins with which the measurement result is compared

Answer 428

Microscopic techniques - protein localization is determined on compartments - eg in mitochondria / ER / GA Detection using antibodies - direct and indirect immunodetection ʹ in both cases we use fluorophore and antibody o Direct immunodetection - fluorophore is attached to the primary antibody o indirect immunodetection - fluorophore is attached to the secondary antibody this will allow signal amplification - fluorophore = molecule capable of absorbing radiation of a certain wavelength and emitting radiation of a different wavelength (= detected signal) Fluorescence vs. confocal microscopy - fluorescence microscope - the eyepiece receives a signal from the entire tissue sample, which means that the relative position of the molecules cannot be reliably detected because the signal from different layers of the sample overlaps - confocal microscope ʹ eliminates the main problem of fluorescence microscopy, thanks to which the eyepiece receives a signal only from one specimen plane/layer (so-called confocal plane) Detection by GFP (green fluorescent protein) labelling - GFP is a small protein and natural fluorophore, isolated from the jellyfish Aequorea victoria, binds covalently o is used as a reporter protein, which assists in determining the location of a given protein in a cell - it is necessary to transfect (insert by virus) the cells with an expression vector containing the sequence coding for the respective protein linked to the sequence coding for GFP - risk of artifacts - in order for GFP to function properly, it must associate with the target protein - but this binding may affect the target protein parameters (biological function, binding interactions and localization itself) - visualization is performed by confocal or fluorescence microscopy Cell fractionation - the lysed cells are subjected to centrifugations of different centrifugal force - which fraction contains the protein is studied by other methods - purity of individual fractions is confirmed by organelle markers (eg COX IV for MIT, lamin A / C for core)

Answer 429

SDS-PAGE + Western blot - for WB detection we can use calorimetric reaction or chemiluminescence - negatively charged proteins are pulled through the gel to the positive electrode -> shorter proteins travel further than longer - Detection of specific proteins usually occurs by specific antibodies and chemiluminescence or color reaction to form an insoluble product o to compare expression between samples it is necessary to analyze the same amount of protein in all samples - the same application is proved by detection of some housekeeping protein ;actin͕ tubulin͕ GAPDH) 2D electrophoresis - separation by two parameters - isoelectric focusing (charge separation) and SDS-PAGE (size separation) - after SDS-PAGE, proteins are identified by Coomassie Brilliant Blue and mass spectrometry ELISA = Enzyme-linked immunosorbent assay - we can use specific antibodies and a calorimetric equation - allows detection and quantification of the test substance in a sample of body fluid ;plasma͕ serum͕ or urine͙ o is used routinely in immunology - eg for the detection of HIV infection - method procedure - example: screening for antibodies against a specific antigen in serum - ELISA is used to detect antibodies (allergy, vaccination success rate), viral infections (hep B, hep C, HIV), hormones (HCG, LH, TSH, T3, T4), pro-inflammatory markers in the blood (cytokinesͿ͙

Answer 430

Flow cytometry - is mainly used in hematology and immunology to analyze the expression of surface molecules - used to analyze individual cells - detection with fluorescently labeled antibodies or other fluorescent probes o eg propidium iodide - analysis of cell cycle phases - this method allows to analyze several parameters simultaneously and at the same time can sort them according to certain selected qualities - intracellular protein expression can also be determined after plasma membrane destruction

Answer 431

Gene knock-down and siRNA - siRNA = small interfering RNA - decrease of protein expression from cellular mechanisms of defense against dsRNA (mechanisms of antiviral defense) - is performed by modifying the genetic material of the test cell and observing the effect of significantly decreasing the expression of the respective protein Gene knock-out - both alleles of a particular gene are deleted or their expression reduced to 0 - allows you to get an idea of the role of the knockout gene - loss of some genes is lethal already in embryonic development - eg knock-out of caspase 9 in the mouse degenerates the brain Protein over-expression - the effect of excess protein is monitored - used for protein purification for another method (eg for determination of enzyme kinetics, 3D structure) - it is necessary to transfect the cells with an expression vector containing the sequence encoding the protein of interest - bacterial cells can be used to propagate expression vectors (so-called expression vector transformation)

Answer 432

- the immune system is one of the basic mechanisms for maintaining the stability of the internal environment o recognizes harmful from harmless and thus protects the body against external and internal threats - immunogenetics studies the inheritance of antigen recognition inheritance - antigen - any factor that induces an immune response - immunity is divided into natural and adaptive and each of these types has a cellular and humoral component

Answer 433

- first-line - skin and mucosa integrity, mechanical defence (cilia movement), chemical defence (gastric juice), microbial defence (intestinal microflora) - second line self-specific defence o cellular component - phagocytic cells, NK cells o humoral component - complement system, interferons

Answer 434

- specific to vertebrate animals only - features of adaptive immunity o specificity - specialized antibodies to individual antigens o Diversity o memory - B memory cells are stored after the first infection and function faster and more efficiently at the next infection o clonal expansion - immune cells multiply by mitosis of the clone that is most effective against a particular antibody o specialization o contraction and homeostasis o No reactivity with the body's own cells - cellular component - T lymphocyte, B lymphocyte - humoral component - antibodies produced by B lymphocytes - the large variability of specific immune responses is encoded in the genome - specific selective response is the result of somatic recombination and gene rearrangement (antigen receptors - TCR and Ig) as well as extensive gene polymorphism (antigen-presenting molecules - HLA)

Answer 435

- a receptor formed from immunoglobulins - 2 light chains - there are 2 isotypes κ and λ o marked as L as Light o The Ig receptor heavy chain genes are located on chromosomes 2 and 22 - 2 heavy chains - there are ρ isotypes μ, δ, γ, ε, α o marked as H as Heavy o The Ig receptor heavy chain genes are located on chromosome 14 o determine the class of immunoglobulins (M, D, G, E, A) - TCR (T-cell receptors) o they consist of a basic α н ß chain or δ н γ chain and may have other additional chains o each chain contains a constant region and a variable region with V, (D), J subsegment - antigen binding site o always transmembrane

Answer 436

- during lymphocyte activation, immunoglobulin genes are randomly rearranged so that each newly matured lymphocyte has a different receptor - allelic exclusion - immunoglobulin chains are formed only by genes of 1 chromosome (1 allele) - single chains consist of a combination of V, D and J segments o V 1-100 "variable" segment o D 1-20 "diversity" segment - part of ß chains only o J 1-10 "joining" segment - other ways of creating more unique chains are o Inaccuracy of connecting individual segments o randomly inserting nucleotides into the segment junction region o somatic mutations in the J segment - in total, up to 1011 different immunoglobulins and 1016 different T cell receptors can be generated by these mechanisms

Answer 437

o MHC genes are inherited as haplotypes, no crossing over o Cross-testing: donor-recipient HLA transplant testing͖ many other tests before transplantation͙

Answer 438

- AB0 genes do not encode structural proteins - new information - genes for antigens A and B are on chromosome 9 o The H antigen gene is on chromosome 19 o antigen D (determining factor of Rh system) is on chromosome 1 o there is also MN system - blood group M (genotype MM), N (genotype NN) and MN (genotype MN) - there may be a so-called hh allele (Bombay allele, ), which is an example of recessive epistasis

Answer 439

- Humoral (antibodies, acute phase proteins and complement system) as well as the cellular component of the serum sample are investigated - assessed cellular immunity factors o the representation of immunocompetent cells o number of individual cell types / subpopulations / precursors o Functional tests - change of phenotype (membrane trait) in transformation of function (activation) in vivo and in vitro o production of cell products (antibodies, cytokines) o Changes in nuclear material - almost all tests are based on an antigen-antibody reaction - immunocomplexes are rarely visible by themselves and are therefore conjugated to an enzyme, fluorochrome or solid - the antigen can be expressed in the tissue, which then makes the tissue or cell visible

Answer 440

Agglutination, Precipitation in gel, Turbidimetry and nephelometry, Immunoreaction with marked antibodies, Electrophoresis, Immunofixation, Immunoblotting (Western blot), Indirect immunofluorescence

Answer 441

- principle- reaction between antibody and antigen results in the formation of a clot visible to the naked eye (called agglutinate) - application of agglutination- detection of infectious and autoimmune diseases, determination of blood groups

Answer 442

- in an agarose gel - antigen is injected into one cell and serum into the other; Antibodies and antigens travel in all directions, and when they meet, they form a "cloudy solution / clot" - It takes a long time

Answer 443

- they are fast, fully automated methods suitable for analyzing large quantities of samples - both these methods use the same experiment, but measure different parameters - a beam of light is sent from the source through the sample container and the resulting intensity is measured a o The intensity of the scattered light is measured in nephelometry o In turbidimetry, the intensity of light passing through the sample in the original direction is measured - principle- measuring the amount of antibody-antigen immune complexes in excess of antibodies - evaluation- the antigen concentration is directly proportional to the rate of turbidity formation and density of the resulting turbidity - use- determination of serum immune protein concentration

Answer 444

- RIA - antibodies are labeled with a radioisotope - EIA - antibodies labeled with an enzyme o detection of reaction by substrate - photometry, fluorometry or luminometry - ELISA - the antigen is bound to the solid phase o the determination of optical density is done photometrically - the higher the color saturation of the resulting solution, the higher the concentration of the substance to be determined o application- high sensitivity (<1ng / l), high specificity and reproducibility determination of IgG against Clostridium tetani

Answer 445

- Immunofixation - detection of paraprotein (product of pathological plasma cell clone) / monoclonal immunoglobulin o diagnosis of monoclonal gammopathies (multiple myeloma, macroglobulinemia, CLL, B-lymphoma)

Answer 446

1) electrophoresis - size division 2) transfer of proteins from the gel to the nitrocellulose membrane in an electric field 3) immunodetection - serum sample + labelled secondary antibody (HRP) + substrate = color reaction - demonstration of the presence of antibodies against individual antigens (bacterial, autoantigens, ...) - Detection of several antibodies against specific antigens at the same time - immunoblot - commercially artificially purified or recombinant membrane-fixed antigens

Answer 447

- direct immunofluorescence has fluorescently labelled primary antibodies - indirect immunofluorescence has fluorescently labelled secondary antibodies o This leads to so-called amplification - the signal is then much more detectable - autoantibodies- somatic antibodies that react with or to their own bodies components o physiologically in very low concentrations, with age their number increases o an organ can be non-specific or organ specific (against B-cells = type 1 diabetes mellitus) - ANA antibodies (anti-nuclear) - react with nuclear antigens (dsDNA, histones, nucleoli, mitotic apparatus)

Answer 448

Flow cytometry (FACS, Fluorescence-activated cell sorting), Functional lymphocyte tests, Phagocytic function tests

Answer 449

- a method based on the change of direction of the laser beam when it hits the cell o the solution flows through a thin glass tube to which the laser is illuminated - the cells in the solution will reflect the laser in different directions and according to the different properties of the emitting beam the peripheral PC can determine which cells are in the solution - FACS can simultaneously measure many parameters of flowing cells such as size, pH, membrane potential, granularity, expression of surface - application- cell phenotyping (diagnosis of primary immunodeficiencies, autoimmune diseases, leukemia and lymphocytes, monitoring of patients after transplantation), functional tests of leukocytes and platelets, evaluation of spermatogenesis, detection of viruses, bacteria and parasites, chromosome examination, enzyme activity examination, intracellular calcium

Answer 450

- expression of activation markers - early (CD69, CD25, CD71) and late (VLA) markers - proliferation - cytotoxicity - cytokine secretion - production of antibodies - use of lymphocyte functional tests o SCID diagnostics o diagnosis and prognosis of malignant tumours o monitoring of cellular immunity (secondary immunodeficiencies, traumas, sepsis, postoperative conditions) o monitoring graft development following bone marrow transplantation o testing of new drugs (pharmacology, anti-tumour immunotherapy)