Physiology: miscellaneous stomach

Question 1

What are the 3 ways in which the mucosal barrier protects the stomach against acidic gastric juice?

Answer 1

Layer of HCO3- rich mucous on the stomach wall (neutralises the acid)
Mucosal epithelial cells are joined by tight junctions - prevents leakage into underlying tissues
Damaged epithelial cells are rapidly replaced - via stem cells

Question 2

What are the 3 phases of gastric acid secretion?

Answer 2

• Cephalic phase
• Gastric phase
• Intestinal phase

Question 3

Do you need to know the stimuli at each of these phases?

Answer 3

Yes

Question 4

What are the 2 sites of stomach ulcers?

Answer 4

Gastric ulcers - stomach
Duodenal ulcers - duodenum

Question 5

What non infective causes can lead to stomach ulcers?

Answer 5

○ High acid and pepsin content
○ Irritation of mucosa
○ Poor blood supply
○ Poor mucus secretion

Question 6

What is an infective cause of stomach ulcers?
What 2 mechanisms does its presence lead to ulcers?

Answer 6

Inhibits somatostatin release from D cells –> more proton pump insertion –> more acidic
Breaks down mucosal cells –> more vulnerable to acid