5. Regulation of gastric secretions

Question 1

What are the two cell types in the antral gland responsible for the regulation of gastric acid secretion?
What binds to these cells?

Answer 1

D cells - Hydrogen ions

G cells - food

Question 2

What is the function of G cells and the subsequent events involved in the regulation of gastric acid secretion?

Answer 2

G cells respond to food in the pyloric antrum by secreting gastrin into the blood.
Gastrin then activates and then stimulates parietal cells to secrete hydrogen ions (upper body of stomach)
When food is not detected by its receptors, G cells stop producing gastrin - negative feedback

Question 3

How are D cells involved in the regulation of gastric acid secretion?

Answer 3

Hydrogen ions binding to D cells activates them, causing the production of somatostatin
Somatostatin acts on parietal cells to inhibit adenyl cyclase.
Adenyl cyclase antagonises the stimulatory effects of histamine and therefore reduces acid production