Exam 2 Flashcards
Hormones
-carried by the blood stream
-chemical compounds secreted by endocrine glands
Steroid hormone
-lipid soluble
-formed from cholesterol
-produced by gonads and adrenal cortex
-ex: cortisol
Protein hormone
-water soluble
-consists of amino acid chains
-3 sub groups
-ex: parathyroid hormone
3 subgroups of protein hormones
-polypeptides
-oligopeptides
-glycoproteins
Biogenic amine
-water soluble
-derived from amino acid that is modified
-ex: norepinephrine
a hormone will only affect a cell that has a specific ___ for that hormone
receptor
agonist
chemical that binds a receptor and initiates a biological response
antagonists
a chemical that binds a receptor and inhibits a biological response
affinity
how tightly a ligand (hormone) binds to a protein (receptor)
efficacy
the relative ability of a drug-receptor complex to produce a functional response
half-life
the time it takes for a chemical to be removed or deactivated by the body
plasma membrane bound receptors
-G-coupled receptors
-receptor tyrosine kinoses
-cytokine receptors
Intracellular receptors
steroid-like receptors
G-protein coupled receptors
bound to the plasma membrane and allow for signal amplification
Hydrophobic hormones
act via intracellular receptors and direct gene activation
Three types of stimuli that can cause hormone secretion
- humoral stimulus
- neural stimulus
- hormonal stimulus
Humoral stimulus
-hormone release caused by altered levels of certain critical ions or nutrients
-Stimulus: low concentration of Ca2+ in capillary blood
Response: parathyroid glands secrete parathyroid hormone (PTH), which increases blood Ca2+
Neural Stimulus
-hormone release caused by neural input
-Stimulus: action potentials in preganglionic sympathetic fibers to adrenal medulla
-Response: adrenal medulla cells secrete epinephrine and norepinephrine
Hormonal stimulus
-hormone release caused by another hormone (a tropic hormone)
-Stimulus: hormones from hypothalamus
-Response: anterior pituitary gland secretes hormones that stimulate other endocrine glands to secrete hormones
Feedback loops
the main regulatory mechanism for hormone secretion in the endocrine system
Hypothalamus
-the master regulator of hormone release
-paraventricular nucleus (PVN)
-supraoptic nucleus (SON)
the pituitary gland lies
directly beneath the hypothalamus in the skull
what connects the pituitary gland to the hypothalamus?
pituitary stalk/ infundibulum
anterior pituitary
-mostly endocrine gland cells: adenohypophysis
Posterior pituitary
-mostly axons/terminals: neurohypophysis
-ADH
-oxytocin
-peptide hormones produced in neurons supraoptic and paraventricular nuclei of hypothalamus
-“long axon pathway” to posterior pituitary
-hormone released from axon terminals
-small 9 aa peptides with 2 aa difference
How the hypothalamus controls release of hormones from the posterior pituitary gland
-Neuroendocrine cells
1. Hypothalamic neurons synthesize oxytocin or antidiuretic hormone (ADH)
2. Oxytocin and ADH are transported down the axons of the hypothalamic hypophyseal tract
3. Oxytocin and ADH are stored in axon terminals in the posterior pituitary
4. When associated hypothalamic neurons fire, action potentials arriving at the axon terminals cause oxytocin or ADH to be released into the blood
How the hypothalamus controls release of hormones from the anterior pituitary gland: hypothalamic-hypophyseal portal system
- hypothalamic neurons secrete releasing and inhibiting hormones into the hypothalamic capillary bed
- Hormones travel through portal veins in the infundibulum
- hypothalamic hormones exit the anterior pituitary capillary bed to bind to receptors on anterior pituitary cells
- hypothalamic hormones stimulate or inhibit secretion of hormones from the anterior pituitary cells
Hormones controlled by the hypothalamus
-TSH
-PRL
-FSH
-LH
-GH
-ACTH
Multi-tiered negative feedback loop
-controls hormone release
1. hypothalamus releases hormones
2. anterior pituitary releases hormones
3. target organs release hormones
-effects: hormone levels increase and effects on other cells-return to normal range
pituitary hormones activate__
target gland hormone production
hormones from target glands regulate__
target tissue and provide feedback to pituitary and/or hypothalamus
Anti-diuretic hormone
-ADH- vasopressin
-diuresis: water retention
-antidiuresis: water retention
-increases water absorption at kidey
-increases thirst
-vasoconstriction increases BP
3 triggers for ADH release
- low BP
- low BV
- high blood osmolarity (dehydration)
Oxytocin
-GPCR activation causes smooth muscle contractions in mammary gland ducts and for wall of uterus
-in CNS: appears important for social-behavioral
Anterior pituitary hormones are controlled by___
releasing/inhibiting hormones for hypothalamus
Growth hormone (GH)
-anabolic hormone that has metabolic and growth promoting actions
-GHRH
-GHIH
GHRH
-GH releasing hormone
-produced by anterior pituitary somatotropin cells
-function is to regulate and control growth
-anabolic hormone builds macromolecules
-target tissues of GH pathway include muscle, adipose, liver, cartilage, and bone
-direct and indirect effects
direct effects of GH
-adipose: stimulate lipolysis, decrease glucose uptake
-liver: increases gluconeogenosis, increases IGF production
-muscle: stimulates aa uptake/protein synthesis, decreases glucose uptake
indirect effects of GH (from IGF signaling)
-increase organ size and function
-stimulate linear bone growth
Growth hormone disorders
-GH hypersecretion: gigantism and acromegaly
-GH hyposecretion: pituitary dwarfism
Prolactin (PRL)
-stimulates milk production in females
-tonic release in both males and females
-release is primarily controlled by inhibitory hormone from hypothalamus, prolactin inhibitory hormone (PIH, dopamine)
Lactotrophs
-in anterior pituitary release prolactin
-females: target mammillary glands by increasing milk production, suckling inhibits PIH to increase milk production
Gonadotropins
-FSH
-LH
-regulate function of the gonads
Hypothalamic gonadotropin releasing hormone (GnRH)
-stimulates anterior pituitary gonadotroph cells
gonadotrophs
produce and secrete FSH/LH
Female gonadotropins
-FSH promotes ovarian follicle/egg maturation and estrogen production
-LH surge triggers ovulation and release of ovarian hormones
-estrogen/progesterone provide negative feedback to anterior pituitary and hypothalamus
Male gonadotropins
-FSH stimulates tetes to induce spermatogenesis
-LH stimulates testes to produce testosterone
-testosterone provides negative feedback to anterior pituitary and hypothalamus
thyroid gland location
-in the anterior neck
-wraps around anterior and lateral trachea
-inferior to larynx
-adjacent to common carotid arteries, internal jugular veins, vagus nerve
Anatomy of the thyroid glands
-consists of 2 lobes connected across midline by the isthmus
-follicle cells: enclose follice
-parafollicular cells: between follicles
thyroid follicles produce__
-thyroid hormone
-microscopic spheres: thyroid follicles
-bounded by follicle cells that produce thyroid hormone
-interior follicle filled with a sticky glycoprotein called colloid which is the storage form of the thyroid hormone
TH
-thyroid hormone
-major metabolic hormone released into circulation as T3 and T4
process of thyroid hormone
- hypothalamus releases TRH: thyrotropin releasing hormone
- anterior pituitary releases TSH: thyroid stimulating hormone
- thyroid follicles produce thyroid hormone in response to TSH (T3 and T4)
3 major biological effects of TH
-regulation of metabolic rate and thermoregulation
-promotion of growth and development
-synergism with sympathetic nervous system
Role of iodide and thyroglobulin
- iodide ions and thyroglobulin are secreted into the colloid
- iodide ions are converted to iodine atoms that attach to thyroglobulin
- iodinated thyroglobulin enters the follicle cell by endocytosis and is converted to T3 and T4 by lysosomal enzymes
- T3 and T4 are released into the blood
How T3 and T4 are released from the thyroid gland
-iodinated tyrosine bound to thyroglobulin in colloid
-pulled from colloid into cell and cleaved from thyroglobulin
-TH’s bind to thyroid-binding globulin for transport
-~90% hormone produced is T4
__ is the form of TH with the greatest biological activity
T3
-amino acids are non-polar and hydrophobic, allowing thyroid hormone to act like a steroid hormone
3 categories of physiological effects of TH
-regulation of metabolic rate and thermoregulation (BMR)
-promotion of growth and development
-synergism with sympathetic nervous system
basal metabolic rate
amount of energy required at rest
Regulation of TH
-Stimulus: decreased levels of free T3 and T4 in the blood or exposure to cold
-Receptor: receptors in hypothalamus detect change
-1st tier control: hypothalamus secretes TRH
-2nd tier control: anterior pituitary secrete TSH
-3rd tier control: thyroid gland is stimulated to produce and secrete T3 and 4 into the blood, and also to grow and develop
-effects: increased levels of T3 and T4 in the blood, increased metabolic rate
hypothyroidism
-BMR falls to 40% of normal
-poor memory, lethargic, listless, poor cold tolerance, goiter
-iodide deficiency= can’t make functional TH but pituitary keeps stimulating (high TSH circulating)
hashimoto’s disease
autoimmune antibodies destroy thyroid gland (high levels TSH)
hyperthyroidism
-BMR 10-100% above normal
-nervousness. fine tremor, weight loss, insatiable eating, increased pulse pressure, heat intolerant, sweating, goiter (enlarged thyroid gland)
grave’s disease
autoimmune antibodies activate TSH receptors resulting in increased T3/T4 production (low TSH circulatin)
3 hormones that control calcium balance
-parathyroid hormone (PTH)
-Calcitrol (vitamin D3)
-Calcitonin: parafollicular cells of thyroid gland
3 sites of hormone action
- bone: larger reservoir of body calcium
- kidney: site of calcium excretion
- gut/GI tract: site of calcium absorption
Parathyroid hormone (PTH)
-increases plasma Ca2+ concentration
-PTH mobilizes Ca2+ from bone
-PTH enhances renal reabsorption of Ca2+
-PTH indirectly increases intestinal absorption of Ca2+
Calcitrol (D3)
-facillitates the intestinal absorption of calcium
-synthesized from vitamin D in body
-2 steps: first in liver, second in kidney (requires PTH)
-main hormone that facilitates absorption of calcium from intestine
-helps renal absorption and mobilization from bone
Calcitonin
-reduces plasma calcium concentrations
-produced by thyroid gland parafollicular cell (c cells)
-decrease blood calcium, opposite to PTH and calcitrol
-inhibits activity of osteoclasts allowing for unopposed bone growth
___ and ____ are main hormones regulating blood calcium concentration
parathyroid hormone and calcitrol
Anterior pituitary coricotroph cells
regulate hormones from the adrenal gland
Adrenal Gland
made up of the outer adrenal cortex and the inner adrenal medulla
Adrenal cortex
-an endocrine gland with 3 continuous layers
-Zona glomerulosa
-Zona fasciculata
-zona reticularis
adrenal medula
-secretes the catecholamines epinephrine and norepinephrine under control of the sympathetic nervous
Zona glomerulosa
-produces mineralocorticoids including aldosterone
Mineralocorticoids
-regulates electrolyte balance
-maintaining chemical gradients is critical to cellular function
changes in Na+ can alter BP
-changes in K+ can change resting membrane potential in neurons
Primary mechanisms of aldosterone secretion
-renin-angiotensin-aldosterone mechanism (RAAS)
-plasma K+ concentrationS
Secondary mechanisms of aldosterone secretion
-adrenocorticotropic hormone (ACTH) from anterior pituitary
-atrial natriuretic peptide (ANP) from atria in response to high atrial stretch (increase in BP)
Cortisol
-mediates the body response to stress primarily by regulating the concentration of blood glucose
-produced by the zona reticularis and zona glucocorticoids
-lipophilic, can enter cells
-binds to cystolic glucocorticoid (steroid) receptors (GR)
-complex acts as transcription factor to activate or repress genes on a variety of tissues
cortisol secretion is controlled by
hypothalamic pituitary-adrenal (HPA) axis
Metabolic cortisol actions
-metabolic-liver: stimulates gluconeogenesis
-fat: stimulates lipolysis, inhibits glucose storage as fat
-muscle: stimulates protein catabolism (amino acids for glucogenesis, inhibits glucose uptake)
Vascular cortisol actions
enhances adrenergic receptors (epinephrine) function to maintain vascular tone and pressure
Anti-inflammatory/immunosupressive cortisol actions
-stress increases inflammatory mediators -> tissue damage
-cortisol inhibits inflammatory agents
-reduces T lymphocytes/interferon production, decreases antibody production
-important in inhibitation of transplant rejection
chronic stress or medication cortisol actions
-centripital (trunk) obesity
-muscle wasting and thin skin from connective tissue loss
-increased infections from immune supression
-bone reabsorption/loss: osteoperosis
-sodium reabsorption and potassium loss
Cushings disease
-excess cortisol
-results from tumor in cortisol producing cells
-iatrogenic cushings syndrome results from long-term administration of corticosteroids
-symptoms: elevated blood glucose, loss of muscle and bone, water and salt retention: hypertension + edema, poor wound healing
Addisons disease
-results from hyposecretion of cortisol and aldosterone
-deficits in glucocorticoids and mineralocorticoids
-symptoms: weight loss, plasma sodium and glucose levels decrease, potassium levels go up, dehydration and hypotension
Androgens
-male sex hormone
-produced by adrenal cortex
-weak androgens that are converted to testosterone
-small amount compares to gonads
Exocrine pancreas
acinar cells produce digestive enzymes and buffer
Endocrine pancreas
islets of langerhans cells produce hormones
pancreatic islets
-produces insulin and glucagon
-alpha: cells (20%) secrete peptide hormone glucagon
-beta: cells (80%) secrete peptide hormone insulin
Glucagon
-promotes reactions that increase blood levels of glucose
-extremely potent hyperglycemic agent
-primary target is the liver
-breakdown of glycogen to glucose (glucogenolysis)
-formation of new glucose (glucogenesis)
-increases lipolysis
-release of amino acids from muscle tissue
insulin
-promotes reactions that decrease blood levels of glucose, promote protein synthesis and fat storage
-primary targets are liver,muscles, adipose tissue, brain
-inhibits breakdown of glycogen to glucose
-inhibits conversion of amino acids or fats to glucose
-
How does an islet cell know to reduce insulin?
-increase in blood glucose results in glucose entry into B-cells through the Glut2 glucose transporter
-cellular glucose metabolism results in increase ATP
-increase in ATP inhibits intracellular K+ efflux
-increase in cellular results in cell depolarization and calcium entry
-increased intracellular calcium stimulates insulin release from secretory granules
Insulin causes glucose uptake into muscle and fat cells by
regulating insertion of GLUT4 transporters
Insulin regulates glucose movement at liver cells by
regulating bidirectional GLUT2 transports
the skin is composed of
epidermis and dermis
epidermis
keratinized stratified squamous epithelial resting on basement membrane
dermis
-loose and dense irregular connective tissue
-deep to the epidermis
hypodermis
loose connective and adipose tissue
functions of the integumentary system
- protection: mechanical trauma, invasion of pathogens
- sensation: sensory receptors
- thermoregulation: maintenance of internal body temperatures through negative feedback loops
-excretion: waste products lost through sweat - Vitamin D synthesis: UV light reaction with modified cholesterol to produce cholecalciferol
keratinocytes
-main cell type in skin
-production of keratin
-desmosomes anchor cells to neighbors
melanocytes
synthesize melanin
dendritic (langerhans) cell
-phagocytose foreign substances
-activate immune system
Merkel (tactile) cells
-sensory receptor for touch
-associated with sensory nerve endings
Stratum basale
-deepest layer attached to dermis
-closest to blood supply
-youngest keratinocytes
-single row of stem cells continually dividing
stratum spinosum
-several layers thick
-systems of intermediate filaments of spanning cytosol and connecting to desmosomes
-contains dendritic cells
stratum granulosum
-1-5 cells thick
-initiate keratinizations-flatten, nuclei and organelles disintegrate
-prominent cytoplasmic granules
-keratohyalin granules
-lamellar granules
-epidermal wastes barrier
keratohyalin granules
help to form keratin
lamellar granules
contain water-resistant glycolipid
stratum lucidum
-thin translucent band
-transition region between s. granulosum and s. corneum
-cut off from nutrients
stratum corneum
-anucleate keratinocytes
-outermost layer: protection against abrasions and penetration
-glycolipid from lamellar granules creates near waterproof layer
-callus formation-repeated pressure
skin layers are held together by
desmosomes and hemidesmosomes
papillary layer
-20% thickness
-loose areolar connect
-dermal papillae
-meissner corpuscle, free nerve endings, capillaries extended up under epidermis
-blisters form between epidermis and papillary layer
dermal papillae
raised areas of papillary layer
reticular layer
-(80% of thickness)
-dense irregular connective tissue
-collagen and elastic fibers
-striae-stretch marks due to this layer
-blood vessels and accessory structures
epidermal ridges
-form fingerprints
-in thermal skin dermal papillae are arranged on top of dermal ridges
-dermal ridges indent epidermis forming epidermal ridges
-provide enhanced grip
cleavage lines
gaps in the bundles of collagen fibers in the dermis
flexure lines
-dermal folds that occur at or near a joint
melanin pigment
-ranges from orange to black
-synthesized from tyrosine: rate of synthesis increased by UV radiation
-packaged into melanosomes and delivered to keratinocytes
-melanin absorbs UV radiation to protect keratinocyte DNA
Carotene
accumulates in stratum corneum of thick skin giving a yellow-orange pigment
hemoglobin
crimson color of oxygenated blood
accessory structures of the skin
-nails
-hair
-glands (sweat+sebaceous)
Nails
-scale-like modifications of the epidermis
-hard keratin
-nail matrix: nail growth
-clinical indicator of health
yellow tinge of nails
respiratory or thyroid disorder
thickened yellow of nails
fungal disorder
concavity of nails
iron deficiency
horizontal lines in nails
malnutrition
Hair
-consists of dead, keratinized cells
-insulates the head
-grows within follicle
-hair grows from bulb
hair shaft
above the surface
hair root
below the surface
3 concentric layers of hair
-medulla, cortex, cuticle
-dermis brings blood supply to bulb
-movement of hair stimulates sensory nerve endings in bulb
arrector pili
smooth muscle pulls on root to lift hair shaft
Sebaceous glands
-secrete sebum
-found in skin everywhere except palms and soles
-most are outgrowths of hair follicles
-contractions force sebum out to lubricate hair
sweat glands release sweat through
ducts
eccrine sweat glands
-more abundant
-duct extends to pore at skin surface
-merocrine secretion of sweat
-sweat is 99% water its also made of salt, waste, and antibodies
-sympathetic regulation
apocrine sweat glands
-axillary and anogenital
-duct empties into hair follicle
-merocrine secretion of sweat with fatty substances and protein
-bacteria on skin produce odor
-sympathetic regulation
ABCDE rule
-asymmetry
-borders
-color
-diameter
-evolution
pathogens
agents that cause disease
-microorganisms, bacteria, fungi, viruses, single cell protozoans, parasites
abnormal “self” cells
body cells that have been invaded by virus or become cancerous
what provides the first line of defense?
skin and mucosa
intact skin epidermis
-acid mantle of skin
-keratin
intact mucous membranes
-mucus
-nasal hairs
-cilia
-gastric juice
protective chemicals
-lysozyme
-defensins
-dermcidin
-mucin
lysozyme
enzyme that breaks down bacterial cell walls
defensins
antimicrobial peptide
dermcidin
antimicrobial protein
mucin
form mucus in digestive and respiratory pathways
leukocytes
-WBCs
-primary cells responsible for the immune response
-granulocytes and agranulocytes
Granulocytes
-neutrophil
-eosinophil
-basophil
agranulocytes
-monocyte
-lymphocyte
chemotaxis
cell movement in an amoeboid fashion following a chemical gradient
phagocytosis
the process of engulfing and ingesting a target pathogen
-cells that do this are phagocytes (neutrophils, macrophages, dendritic cells, B lymphocytes)
antigen-presenting cells
cells that display fragments of foreign proteins in their cell surface
-macrophage/monocyte, dendritic cells, B lymphocytes
cytoxic cells
attack and directly kill pathogens
-eosinophils and some lymphocytes, NK cells and T cells
phagocytes
-can ingest foreign pathogens by phagocytosis
-phagocytic cell recognizes something as foreign
-binds to it and engulfs it in membrane vesicle: “phagosome”
-phagosome fuses with lysosome in cell
-enzymes from lysosome digest engulfed material
opsonization
makes pathogens more visible to phagocyte cells
opsonins
molecules like compliment proteins of antibodies that stick to foreign material
-phagocytes then recognize opsonin
antigen presentation
-digested fragments of pathogen are bound to protein on plasma membrane
-alerts other immune cells to presence of foreign material
Natural killer cells
-type of lymphocyte
-provide rapid response to virus infected cells and tumor cells
-less picky about cellular targets compared to other lymphocytes in adaptive immune system
actions of natural killer cells
-activated only by abnormal cells
-altered balance of normal to abnormal signals
-kills unhealthy cells (cytoxic)
-secrete preforins, punch holes in target cell membrane
-secrete granzymes, enter perferations and trigger opposite in target cells
-secrete interferons and pro-inflammatory chemicals
-activate other immune system activities
Inflamation
hallmark reaction of the innate immune system
4 cardinal signs of inflammation
-redness
-heat
-swelling
-pain
role of histamine prostaglandin in inflammation
-produced from mast cells, most important chemical causing inflammation
-increases capillary permeability
-attracts/activate other immune cells
-increase sensitivity of pain fibers
common drugs to prevent inflammation
-antihistamines block histamine receptors
-aspirin and ibuprofen block prostaglandin synthesis
what is the second stage of the inflammatory response?
phagocyte mobilization
leukocytosis
increase in release and production of neutrophils in the red bone marrow
margination
interaction between cell adhesion molecules (CAMs) on vessel walls and neutrophils
diapedesis
WBCs squeeze through capillary wall
positive chemotaxis
neutrophils reach inflamed area first and monocytes follow (differentiate into macrophages)
interferons
-antimicrobial protein
-help protect unaffected cells from virus
-virus invades healthy cell and uses its cell machinery to make new virus
-interferon protein is packaged into secretory granules and released by exocytosis
-neighboring cells bind interferon which stimulates them to “beef up” their defenses
compliment proteins
-antimicrobial protein
-plasma proteins that help destroy pathogens
-“compliments” the innate and adaptive immune systems in 3 ways
3 ways the compliment proteins affect the innate and immune systems
-opsonization
-enhance inflammation
-insertion of MAC into membranes inducing cell lysis
fever
a systematic response to invading microorganisms
pyrogens
released from damaged cells, raise body temp
3 important aspects of adaptive immunity
-specific
-systemic
-has memory
antigens
substances that trigger the adaptive immune system
functional properties of complete antigens
-immunogenicity
-reactivity
immunogenicity
the ability to stimulate specific lymphocytes to proliferate
reactivity
the ability to react with activated lymphocytes and released antibodies
self antigens
produced by bodies own cells
non-self antigens
produced by bacteria, virus, or from substances outside the body
B lymphocytes
-part of adaptive immune system
-become plasma cells
-recognize an antigen if they have a surface receptor for that particular antigen
-stay in red bone marrow and begin maturation there before being released into general circulation
T lymphocytes
-CD-4
-CD-8
-recognize an antigen if they have a surface receptor for that particular antigen
-migrate to the thymus gland to mature there before being released into fciruclation
Each lymphocyte makes ___ particular antigen receptor, but has many copies of that receptor on its surface
one
immunocompetence
lymphocyte must be able to recognize one specific antigen
-each B or T cell will display a unique surface receptor
-MHC proteins are expressed by all cells
Self-tolerance
must be unresponsive to self-antigen
-failure to ignore normal body cells leads to autoimmune diseases
naive
when a cell hasn’t been exposed to a foreign antigen
Activation of B lymphocytes
-b lymphocyte is activated if its surface receptor binds to the antigen specific for that receptor
-some clone cells differentiate into plasma cells which make millions of antibodies
-other clone cells go dormant as memory B cells
humoral immunity
-in body fluids
-b lymphocyte activation leads to production of antibodies
-can be active, passive, natural, or artificially aquired
memory b cells
provide and enhanced response in a second exposure to an antigen
antibody structure
-4 polypeptide chains (2 light 2 heavy)
-fab region (variable)
-fc region (constant region)
Fab region of an antibody
-variable region
-forms antigen binding sites and confer specificity for a unique antigen
-2 binding sites per antibody
Fc region of an antibody
-constant region
-the same for a given class of antibodies
-dictate the type of cell the antibody can bind to
-dictates how the antibody functions to eliminate antigens
immunoglobins
-5 functional classes of antibodies
-class dictated by Fc region
-IgG most abundant in plasma
-IgD are found on B cell surface
cell-mediated immunity
-t lymphocytes only recognized antigens presented by other body cells
-MHC protein on cell of the surface of a body cell is specific to an individual person and are the basis of tissue matching in organ donation
T cells recognize
both MHC and its antigen
T cell education in the thymus
immunocompetence and self tolerance
positive selection
if T cells can recognize the self-MHC proteins on thymus cells
negative selection
T cells survive if they ignore self antigens
CD4
-type of T lymphocyte
-T helper cells
-interact with class II MHC on antigen-presenting cells
CD8
-type of T lymphocyte
-cytotoxic T cells
-interact with class I MHC on antigen-presenting cells
Class I Major Histocompatibility complex
-found on all nucleated human cells
-all cells synthesize proteins and recycle them, the fragments are then displayed on cell surface
-healthy cell: “self antigen”
-unhealthy cell: “non self antigen”
Class II major histocompatibility complex
-found primarily on antigen presenting cells
-phagocytic cells engulf and digest pathogens and display fragments
major antigen presenting cells
marophages, dendritic cells, b lymphocytes
T cell activation requires
MHC/antigen recognition and co-stimulation
-co stimulatory molecules are only present when cells are abnormal or pathogens are detected
CD8 T cell activation forms
cytoxic T cells
-naive CD8 cells are activated when they encounter abnormal body cells
clone formation of CD8 lymphocytes leads to
-cytoxic T cells
-memory Tc cells
activated T cells release..
cytokines
-signaling molecules influencing activity of immune cells
Cytoxic T cells are the only T cell that can…
directly attack and kill abnormal cells
2 proteins that release from Tc cell and induce cell death
-preforins
-granzymes
immune surveillance
when cytoxic T cells work in tandem with natural killer cells
-NK cells interact with cells that cease to display MHC I
-Cytoxic T cells cannot see cells without MHC I
CD4 T cell activation forms
Helper T cells
clone formation of CD4 leads to…
-helper T cells
-memory Th cells
What is required for full humoral immunity response?
Th cell activation of B cells
What is a more efficient mechanism to activate Tc cells?
cytokines from Th activating them
lymphatic system
-returns leaked fluids to the cardiovasculatory system
-network of lymphatic vessels
-lymph
-lymph nodes
lymphoid organs and tissues
-structural basis of immune system
-spleen, thymus, tonsils, lymph nodes, MALT
lymphatic vessels
-excess interstitial fluid is collected
-more fluid is pushed out than in
-fluid = lymph
lymphatic capillaries
-highly permeable
-overlapping endothelial cells
-collagen filaments tie overlapping “flaps” to surrounding connective tissues
-fluid and solutes enter, including bid proteins, cells, bacteria
capillary flaps close when
interstitial pressure < lymphatic pressure
capillary flaps open when
interstitial pressure is > than lymphatic pressure
flow of lymph
-returned to the blood near the heart
-collecting vessels –> lymphatic trunks –> lymphatic ducts
-lymph empties into subclavian vein close to heart
-right lymphatic duct drains upper right quandrant
lymphoid tissue
-contains cells of innate and adaptive defenses
-B lymphocytes
-T lymphocytes
-antigen presenting cells (macrophage, dendritic cells)di
diffuse lymphoid tissue
no apparent pattern to arrangement of lymphoid tissue
lymphoid follicles
-solid, spherical bodies packed with lymphoid cells and reticular fibers
-lighter central area= germinal center with dividing B cells and plasma cells
primary lymphoid organs
-where B+T lymphocytes mature
-thalamus, red bone marrow
secondary lymphoid organs
-where mature lymphocytes first encounter antigens and are activated
thymus
-genertes immunocompetent T lymphocytes
-no follicles, lack B cells
-does not directly fight antigens
spleen
-site of lymphocyte proliferation, immune surveillance, and blood cleansing
-largest lymphoid organs
-filters blood
white pulp
-spleen
-immune function
-composed of lymphocytes suspended on reticular fibers
-forms cuffs around central arteries
red pulp
-where worn out RBC’s and blood borne pathogens are destroyed by macrophage
lymph nodes
-clusters of lymphatic tissue located along lymphatic vessels
-hundreds embedded in connective tissue
-clusters in axillae, cervical, inguinal, and mesenteric regions
-filters the lymph
functions of lymph nodes
-cleansing the lymph-mcarophages in the node
-immune system activation-site of lymphocyte antigen interactions
lymph node structures
-capsule, cortex, and medulla regions
flow of lymph through lymph node
-lymph flows into node through afferent lymphatic vessels
-flows through cortex, filled with lymphoid follicles
-B cells, T cells, macrophage, and dendritic cells diffusely distributed in cortex and medulla
-lymph flows out efferent lymphatic vessels
-lymph is screened by lymphocytes and phagocytic cells as it travels one way through the lymph node
MALT
-mucosa-associated lymphoid tissues
-collection of lymphoid tissue clustered in areas prone to pathogen exposure
-found in GI tract
-tonsils, preyers patches, appendix
-composed of spherical clusters of lymphoid follicles (B cells)
