gastric acid

Question 1

Phases of gastric acid secretion

There are 3 phases of gastric secretion:

Answer 1

Cephalic phase (smell / taste of food)

Gastric phase (distension of stomach )

Intestinal phase (food in duodenum)

Question 2

the cephalic phase produces how much acid

Answer 2

30% acid produced

Vagal cholinergic stimulation causing secretion of HCL and gastrin release from G cells

Question 3

the gastric phase produces how much acid

Answer 3

60% acid produced

Stomach distension/low H+/peptides causes Gastrin release

Question 4

the intestinal phase produces how much acid

Answer 4

10% acid produced
High acidity/distension/hypertonic solutions in the duodenum inhibits gastric acid secretion via enterogastrones (CCK, secretin) and neural reflexes.

Question 5

what factors increase gastric acid production

Answer 5

Vagal nerve stimulation - Vagal stimulation suppresses somatostatin release from delta cells,
Gastrin release
Histamine release (indirectly following gastrin release) from enterchromaffin like cells

Question 6

what factors decrease gastric acid production

Answer 6

Somatostatin (inhibits histamine release)
Cholecystokinin
Secretin -Secretin increases bicarbonate secretion from duodenal Brunner’s gland as well; this mechanism buffers the acidity from chyme and reduces secretion of acid by parietal cells.

Question 7

bicarbonate released from what glands to neutralise acid

Answer 7

brunners glands - the submucosa of the proximal duodenum