Final Exam Flashcards
Types of thyroid hormones
Thyroxine (T4) tetraiodothyronine
3, 5, 3 tiiodothyronine (T3)
3, 3, 5 triiodothyronine (rT3)
Thyroid follicle
circle surrounded by blood capillaries. Thyroid colloid in centre that has precursor protein to form all thyroid hormones
Thyroid hormone
only iodine containing hormone
thryoglobulin
must be synthesized to get the tyrosine
Thyroglobulin synthesis
1) tyrosines on thryoglobulin
2) iodination of tyrosine residues - thyroid peroxidase
3) conjugation of iodinated tyrosine residues to form iodinated thyronine (coupling reaction) thyroid peroxidase
4) storage of iodinated thyroglobulin in the colloid (centre part of follicle)
5) Reabsorption of colloid by phagocytotic action of thyroid epithelial cells
6) Enzymativ processing of reabsorbed thyroglobulin in thyroid epithelial cells
DI-Tyr + DI-Tyr=
T4
MI-Tyr +DI-Tyr=
T3 or rT3
MI-Tyr + MI-Tyr=
T2 forms
MI-Tyr +Try=
T1 forms
DI-Tyr + Tyr=
T2 forms
Pathways
Brain - hypothalamus (TRH for positive, DA for negative) - pituitary thyrotropes (TSH for positive) - thyroid - T4 and T3 - action on target cell
TSH receptor effects
cAMP/PKA
cAMP to thyroglobulin
PKA to pentose pathway and ATPase pathway
Thyroid hormone on frog metamorphosis
TRH affects prometamorphosis, TSH affects middle of metamorphosis, T3/T4 more for the end part. Prolactin is a precursor for this.
why do we need more T4 than T3, when T3 seems to be used in more situations?
T4 binds to thyroid hormone binding globulins (TBG) albanin and pre-albanin and there is lots of TBG to be bound to
Glucocorticoid (GRE) Hormone response element
Estrogen (ERE) hormone response element
Thyroid Hormone (TRE) hormone response element
Vitamin D3 (DR+3, VDRE) hormone response element
<AGGTCA
HRE
Hormone Response Elements
are often palindromic
Steroid hormone receptor action on transcription
1) change in conformation and DNA independent phosphorylation
2) Receptor dimerization via Leu-rich region
3) DNA binding & DNA dependent hyperphosphorylation
4) Stabilization of receptor dimer and DNA binding
5) Recruitment tof adaptor proteins and interactions with nuclear transcription factors and transcription activators/regulators elements
6) Regulation of gene transcription
BP
plasma binding protein
TR alpha
TR beta
isoformsq
TR alpha in heart
TR beta in liver
TR and RXR
in mitochondria - can affect maternal mitochondrial DNA
Nuclear Receptors
mediate action of membrane permeant steroid and thyroid hormones (but sometimes they still bind to membrane receptors)
Thyroid on the PLC pathway
Only when TH bind to membranes - alphaVbeta3 - it binds TETRAC (T4)
Deamination of T3 and T4
T4 - TETRAC
T3 - TRIAC
Insufficient Iodine
TSH induced Hypertrophy and goiter
Excess of Iodine
poisoning of peroxidase enzyme
Inhibitors of iodine uptake
cabbage, brussel sprouts, turnips, broccoli (form thiocyanates upon digestion) thioamides can also hinhibit peroxidase enzyme and deiodinase
MSH
Melanotropin Stimulating Hormone (action on skin color in vertebrates)
- mimic background
- skin heat absorption and relection
- visual signalling cues (behaviour)
- protection from UV radiation
Chromatocytes
all colored/pigmented skin cells
chromatophores
subgroup of cells - can rapidly redistribute pigments within them
Two types of color change
Morphological color change (slow, long term affects)
Physiological color change (relatively fast, short term affects)
Chromatosome
organelle containing the pigments
POMC
Pro-opiomelanocortin
(precursor for multiple potentially active peptides)
Pars distalis
Pars intermedia
Pars Distalis
alpha msh and clip (corticotropin like peptide) -> ACTH
beta msh, blank, end (endorphin) -> beta LPH
Pars Intermedia
alpha msh and clip
beta msh and blank -> gamma LPH
end
Physiological color change
melanosome aggregated in melanophore (skin light in color), then add MSH to get melanosome dispersed in melanophore and more surface area is covered by melanin-containing melanosomes, so skin darkens and is less reflective
Melanosomes
organelles than contain melanin
melanin
dark or dark brown pigments
melanophores
cells that contain melanosomes
norepinephrine causes…
aggregation of chromosomes
Irridophore
causes amphibians to appear irridescent - have crystals in cells
Releasing factor of color change
CRH (corticotropin releasing hormone)
Release inhibiting factor for color change is
dopamine
peptide hormone signal transduction
hormone - receptor - G protein - Generation and/or modulation of second messenger levels - modulation of some intracellular biochemical event - biological response
exopeptidase
chews N (aminopeptidase) or C (carboxypeptidase) end of peptide
endopeptidase
chews middle of peptide
Typrsin inhibitor
Part of pancreatic enzymes
Lumen and Brunner’s glands
Lumen is centre open part of gut, surrounded by Brunner’s glands
Peristalic action
circular muscle contraction, coordinated with longitudinal smooth muscle action
Segmentation
hard contraction of circular muscles to create small bolus
Secretin
blood borne factor released by acid on duodenum that stimulates pancreatic enzyme release
Carbohydrate digestion
complex polysaccharides (starch and glycogen) are digested by polysaccharidase (pancreatic amylase) into disaccharides. Then maltase, sucrase, and lactase further breakdown disaccharides to monosaccharides (pentose/hexose) which can be absorbed in gut epithelium via Carrier Mediated Transport Systems
Glycogen
more extensive branching than starch. animal based carbs.
Acidic climates of digestion
mouth - alkaline
stomach - acidic (4-5 ph resting, 1-2 during acid secretion)
intestine - alkaline
GLUT2
only used in high glucose conditions - for glucose fructose and galactose (in enterocyte cells)
GLUT5
for fructose (in enterocyte cells)
Cellulose
Cellulase enzyme to break down in bacteria, snails, anthropods, other vertebrate ferment in gut with bacteria creating short chain fatty acids and methane gas.
Short chain fatty acids
easily absorbed since water and fat soluble.
Chitin
Chitinase to break down, in insect eating animals
Cecum
larger in animals that ferment more (cows and horses) for cellulose digestion
Metabolites and microflora
Microflora release microbolites which decrease inflammatory responses and cancer, probiotics help grow helpful microflora
Lipid Digestion
triglycerol with a glycerol backbone and 3 fatty acid side chains or a phosphosugar and 2 fatty acid side chains
Acidic Lipases
Lingual lipase
gastric lipase
tributyrinases
Alkaline lipases
pancreatic lipases
pancreatic triacyglycerol lipase
lipid emulsifier
bile salts
micelle
single layer of fatty acids, monoglycerides, glycerol and bile salts with HYDROPHILLIC heads OUTSIDE.
can pass through plasma membrane of enterocytes at the microvillus
chylomicrons
lipid droplets coated in proteins formed in epithelial cells of intestine. carried via lymphatic system to venous blood and processed in liver
Glycerol and Fatty acids processed by
Kerb’s cycle and beta oxidation pathways
Most lipid digestion takes place in…
the intestines - pancreatic lipase and cholesterol esterases and bile salts
Protein Digestion
proteases or peptidases (endopeptidases and exopeptidase) endopeptidase usually acts first (found in stomach)
Endopeptidase
Breaks bond in middle of peptides (eg. pepsin in stomach secretion, trypsin and chromotrypsin in pancreatic secretion)
pepsin
needs acidic environment
trypsin and chymotrypsin
needs slightly alkaline environment
Exopeptidase
cleaves off terminal amino acids produced by pancreas
Tripeptidase and dipeptidase
finish off digestion of small peptide fragments in intestine
amino acids and dipeptides absorbed in gut by
carrier mediated transports (amino acid-Na co-transport)
nucleic acid broken down by
nucleases, nucleotidases, nucleosidases
esters
esterase breaks down, formed from an alcohol and an acid
How does the stomach not eat itself?
pepsinogen (inactive) can be cleaved by acid to pepsin (active). thick layer of sugar based mucus. proenzymes and zymogen
proenzymes and zymogen
inactive precursor molecules
trysinogen and chymotrypsinogen
secreted zymogens from pancreas. high pH enterokinase can turn trypsinogen to trypsin.
which in turn, trypsin turns chymotrypsinogen to chymotrypsin.
Nueral vs endocrine
neural is quick
endocrine is more long term
enterochromaffin like cells system
neural and endocrine control of digestive system
etero=gut
chromaffin=a cel type stainable with silver salts
Oral cavity digestion
amylase (in saliva, starts carb digestion)
food chewed to small bolus
mucin (in saliva, glycoprotein; poteinaceous mucopolysaccharide. acts like lubricant for swallowing)
Gastric secretions digestion in stomach
carbs, protein, and some fat digested.
pepsin, amylase, lipase, tributyrase present.
3 phases
3 phases of gastric secretions
Cephalic - initiated and controlled by neuronal input from CNS
Gastric - initiated and controlled by gastric secretions
Intestinal - initiated and controlled by intestinal secretions
Ach
Acetylcholine
SS
somatostatin
GRP
Gastrin releasing peptide
GIP
Gastric inhibitory peptide
VIP
Vasoactive intestinal peptide (stomach motility decrease)
CCK
cholecystokinin (contracts sphincter when exposed to fat)
Intestinal Digestion
completes protein starch and fat digestion. pancreas secretes enzymes for it.
pancreas source of alkaline fluid secretion in intestines.
bile secretion required for fat digestion
Ghrelin
orexigenic hormone (motilin family). secreted in stomach. absorbed in blood. fasting increases ghrelin mRNA expression. levels drop within an hour of feeding. can be trained with schedule of eating regularly. acts on brain to stimulate hunger. stimulates pituitary GH secretion ad GH in turn inhibits ghrelin release
Leptin
anorexigenic hormone. produced by adipocytes. indicator of fat storage. reduce hunger and increase satiation. released by stomach into blood after feeding. can act locally on stomach to decrease gastric secretion and motility. works with ghrelin as antagonistic pair.
Pathogen types
virus, fungus, parasite, bacterium
SCID
Severe combined Immunodeficiency syndrome - no T and B cells (adaptive immunity)
CD4 cells are
essential to having an aquired immune system response
Autoimmune disorder triggers
Stress hormones metals food antigens pesticides & poisons
Cells of innate immunity
granulocytes
monocytes
macrophages
dendritic cells
Cells of adaptive immunity
T cells
B cells
Humoral components (innate)
complement antimicrobial proteins
enzymes
cytokines
receptors
humoral components (adaptive)
antibodies
cytokines
1st, 2nd, and 3rd lines of defense
1st & 2nd are innate (skin, ,mucos membranes, chemicals then phagocytosis, complement, interferon, inflammation, fever)
3rd is adaptive (lymphocytes and antibodies)
Chemical factors as barriers to infection (innate)
fatty acids in sweat
enzymes in tears, saliva, mucos
low pH of sweat and gastric secretions
defensins (small antimicrobial proteins)
Biological factors as barriers to infection (innate)
normal bacterial flora of the skin and GI tract
inhibit colonization by pathogenic bacteria
Secrete toxic substances and compete for nutrients and attachment sites
Hematopoiesis
formation and differentiation of blood cells
Lymphoid progenitor creates ____ Cells
Nk cells
T cells
B cells
dendritic cells
Myleoid progenitor creates _____ cells
monocyte/macrophage neutrophil eosinophil basophil platelets erythrocyte dendritic cells
Myeloid lineage cells are
the first responders to infection
types of granulocytes (which are myeloid in lineage)
neutrophils
basophils
mast cells
eosinophils
myeloid antigen presenting cells
monocytes
macrophages
dendritic cells
Granulocyte granules..
directly damage pathogens, regulate immune cell movements, regulate the activities of other immune cells, and contribute to tissue damage and remodelling
chemokines
major chemoattractant
What is complement system
cascade of immune proteins activated by infections. different complement proteins have different functions
lactoferrin & transferrin
proteins that bind iron that is required for bacterial growth
lysozyme
enzyme that breaks down the cell well of bacteria
interferons (type of cytokine)
immune proteins that limit virus replication in cells
cytokines
hormones of the immune system, proteins that initiate and regulate immune response (kenkines are smaller cytokines) (interlucin is a cytokine)
monocytes vs macrophages
monocytes - more immature form of macrophage - looks like small compact cell
macrophage - involved in phagocytic processes, picking up stuff in envionrment for antigen recognition (further differentiated monocyte) - look like ball with lots of pieces coming off
