Stomach

Question 1

What is the function of the suspensory muscle of the duodenum?

Answer 1

Contraction of the muscle allows widening of the flexure angle to aid movement of intestinal contents into the jejunum.

Question 2

In the cephalic phase, acetylcholine released due to vagal stimulation can bind to which cells?

Answer 2

1) Muscarinic receptors directly on parietal cells
2) ECL cells, causing histamine release which bind to H2 receptors on parietal cells
3) G cells, causing release of gastrin which bind to CCKB receptors on parietal cells.

Question 3

What triggers the cephalic phase?

Answer 3

Sight, smell, taste of food, up to 30 mins before food.

Question 4

What triggers the gastric phase?

Answer 4

Distension of the stomach (vago-vagal reflexes) and presence of amino acids and peptides (stimulate gastrin secretion)

Question 5

What triggers the intestinal phase?

Answer 5

Chyme in the duodenum.

Question 6

What are the excitatory components of the intestinal phase?

Answer 6

Amino acids and peptides stimulate intestinal gastrin release (carried to stomach via blood).

Question 7

What are the inhibitory components of the intestinal phase?

Answer 7

Low pH, fat, and distension. Result in the release of somatostatin from D cells (inhibit parietal cells acid secretion). Low pH results in secretin release into bloodstream by S cells and fatty acids cause GIP release from K cells and CCK release from I cells.

Question 8

What is the action of secretin?

Answer 8

Inhibits release of gastrin by G cells, stimulates pepsin release, stimulates pancreatic/biliary bicarbonate secretion.

Question 9

What is the action of GIP?

Answer 9

Inhibit parietal cell acid secretion and G cell gastrin release, and stimulates insulin release.

Question 10

What is the action of CCK?

Answer 10

Gallbladder contraction, pancreatic enzymes/bicarbonate secretion, inhibit parietal cell acid secretion and inhibit gastric emptying.

Question 11

What stimulates gastrin release?

Answer 11

Ingested proteins reach antral end of stomach

Question 12

What cells are found in oxyntic glands?

Answer 12

Mucus neck cells: secrete mucus
Parietal cells: HCl and intrinsic factor
Chief cells: pepsinogen
Enteroendocrine: ECL cells, D cells, VIP cells,

Question 13

What cells are found in pyloric glands?

Answer 13

Mucus neck cells: secrete mucus (majority)
G cells: gastrin
D cells: somatostatin
Parietal cells: HCl

Question 14

What additional cells are found in the small intestine?

Answer 14

I cells: CCK
S cells: secretin
K cells: GIP

Question 15

What are the 3 main motor functions of the stomach?

Answer 15

1. Storage of food
2. Mixing of food to give chyme.
3. Slow emptying of chyme into the duodenum.

Question 16

What gastric factors can increase gastric emptying?

Answer 16

• Food in the stomach causing distension

- Gastrin

Question 17

What intestinal factors can inhibit gastric emptying?

Answer 17

Via local enteric NS impulses to the stomach
Via sympathetic NS from prevertebral ganglia 
Via the brainstem
- inhibit pyloric pump
- increase pyloric sphincter tone
- duodenal distension
- irritation of duodenal mucosa
- acidity of chyme (pH <3/4)