4 Secretions of the stomach

Question 1

What do mucous neck cells secrete?

Answer 1

mucous

bicarbonate

Question 2

What do parietal cells secrete?

Answer 2

Acid

IF

Question 3

What do EC like cells secrete?

Answer 3

histamine

Question 4

What do chief cells secrete?

Answer 4

pepsinogen

lipase

Question 5

What do D cells secrete?

Answer 5

somatostatin

Question 6

What do G cells secrete?

Answer 6

gastrin

Question 7

What are the 4 main parts of the stomach?

Answer 7

fundus
corpus
antrum
pylorus

Question 8

How does the parietal cell secrete acid?

Answer 8

H2O into the cell
broken into OH- and H+
H+ out into lumen (H+/K+ transporter)
OH- joins with CO2 to form HCO3-
ALKALINE TIDE OUT
Cl- channel into gut lumen forms with HCl in gut lumen

Question 9

What are the 3 stimuli for acid secretion, their receptors, and the cell pathways?

Answer 9

ACh - M3 - Gq
Histamine - H2 - Gs
Gastrin - CCK(B) - Gq

Question 10

What are G cells, and where are they located?

Answer 10

Secrete gastrin, in the anturm of the stomach, into the blood. It then stimulates acid production in other areas. sitmulated by ACh (Vagus nerve)

Question 11

What is somatostatin?

Answer 11

inhibitor of acid secretion, secreted by D cells. binds to parietal cell receptors actin in a Gi mechanism, or onto ECL cells to inhibit histamine release.
inhibited by vagus nerve

Question 12

What causes ACh release by the Vagus nerve?

Answer 12

stomach distension

Question 13

What stimulates Gastrin release?

Answer 13

ACh

products of proein digesrtion stimulate G cells to release gastrin - positive feedback

Question 14

What is secretin?

Answer 14

released by duodenal S cells

stimulated by fat and acid in the duodenum, it inhibits antral gastrin release and promotes somatostatin release

Question 15

What is CCK?

Answer 15

cholecystokinin

preoduced by I cellsin the duodenum and jejenum is response to fat, decreasing parietal cell acid secretion

Question 16

What is Omezaprole?

Answer 16

PPI

Question 17

What is are Cimetidine and Ranitidine?

Answer 17

H2 receptor antagonists

Question 18

What are the 4 stages of acid secretion?

Answer 18

basal phase - contemplative
cephalic phase - smell and taste
gastric phase - proper
instestinal phase - stimulated by partially digested stuff

Question 19

What are pepsinogens stimulated by, what happens to them?

Answer 19

ACh stimulation of chief cells, they turn into pepsins when pH<5, works by autocatalysis
activation is irreversible at pH 7.2

Question 20

What does the mucous layer do?

Answer 20

traps local HCO3-, maintaining a local pH = 7

Question 21

What are prostglandins important for?

Answer 21

maintaining mucosal diffusion barrier
1 - inhibit acid secretion
2 - stimulate HCO3- secretion
3 - stimulate mucus secretion

Question 22

What can H.Pylori cause in the antrum?

Answer 22

G cell gastrin hypersecretion
D cell somatostatin hyposecretion
ultimately hypergastrinaemia - ulcers

Question 23

What can H.Pylori cause in the corpus?

Answer 23

reduced acid secretion and hypochlorhydria

Question 24

What is intrinsic factor needed for?

Answer 24

Vitamin B12 absorption in the terminal ileum, produced by parietal cells
Without it it can cause pernicious anaemia