de Lisle: Secretion, biophysiology of GI Flashcards
why are parietal cells more eosinophilic?
more mitochondria
why are chief cells more basophilic?
more rough ER = more RNA = for transport of pesinogen
Where is secretory surface of partietal cell?
Canaliculus
are there chief cells in pyloric stomach?
no just body/fundus
Antrum and pyloric have what sort of cells?
Enteroendocrine cells: G and D cells.
Somatostatin blocks what portion of the Gi cascade?
Adenylate cyclase
Acetylcholine and Gastrin act through
PLC/IP3 and Ca cascade
CCKb has higher affinity for
Gastrin
Calcium and cyclate= synergistic affect exmaple
gastrin triggers Ca cascade also stimulate G cells in pyloric region to stimulate ECL cells to stimulate release Histamine which acts through Adenylate cyclase
Where is the H/ATPase on the cell?
Apical surface
parietal cell inhibitors?
Somatostatin
PGE2
CCK
PACAP (pituitary adenylate cyclase-activating peptide) stimulates ________ release from ECL cells ( in the body/fundus) when stimulates by _______ in the G cells of the pyloric region
histamine,
gastrin
HKatapse on the apical side of the parietal cell.
Pumps H out to the lumen, HCO3 pumps passes into the blood stream and Cl into the cell to balance the charge difference
Cl- exits through Chloride channel to form HCl.
What causes the alkaline tide?
HCO3 moving basolaterally into the blood as H moves to the lumen
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What enzyme is critical in producing H+ and HCO3- from CO2 and H2O and can be found in parietal cells of the stomach body, pancreatic and liver bile ducts, Brunner’s glands of the submucosa, and intestinal crypts?
Carbonic Anhydrase
In an inactive parietal cells, where are the H, K/ATPase’s located?
in the tubulovesicle
In the stimulated state, core actin filaments have vast rearrangements causing the canalicular space to fill with?
Microvilli
if you stained for actin in a stimulated parietal cell, you would see
super bright green staining
Why doesn’t the proton pump work when it’s in the tubulovesicle (not endocytosed with the canalliculi
the proton would be pumped into the tubulo vesicle and as it’s endocytosed the proton pump faces the lumen
What drug irreversibly inactivates the proton pump and could allow C Diff proliferation because of lack of acid.
omeprazole, lansoprazole (PPIs)
Where is protein first digested?
In the stomach by pepsin (pepsinogen released by chief cells)
Where does the alkaline tide from parietal cells circulate to?
goes through capillaries to epithelium to protect.
if the epithelia of the stomach are damaged what happens?
The living cells migrate up to the epithlia short term before cell division occurrs.
what epithelia over peyer’s pataches in the ileum?
squamous amongst ileal simple columnar epithelia
is M cell an antigen presenting cell?
no, just endocytoses.
Doesn’t digest anything,
what’s the major Ig of the body and where is it transported usually?
IgA, mucosal surfaces.
