Stomach

Question 1

Functions of the stomach

Answer 1

Store food
Minimise ingestion of bacteria
Dissolve & partially digest macromolecules in food
Regulate rate of stomach contents into S.I
Secrete intrinsic factor

Question 2

What are the two parts of stomach for motility?

Answer 2

Orad = fundus & body
Caudad = visceral part of body & antrum

Question 3

What occurs in receptive relaxation?

Answer 3

Empty stomach is contracted & folded into rugae, which undo when food enters stomach & increases volume from 50ml to 1.5L

Question 4

What occurs in the mixing stage?

Answer 4

Peristaltic waves in body of stomach moves contents towards antrum, causing contraction that closes the pyloric sphincter. This forces contents back into the stomach body, causing retropulsion.

Question 5

What occurs in the emptying stage?

Answer 5

Coordinated contractile activity of the stomach, pylorus & proximal S.I

Question 6

What is the pyloric sphincter?

Answer 6

Ring of smooth muscle & connective tissue between gatric antrum & duodenum.

Question 7

What are the contents of gastric secretions?

Answer 7

HCl, mucus, enzymes & intrinsic factor

Question 8

What are the 4 main secretory epithelial cells of the stomach & what do they secrete?

Answer 8

Parietal cells (in oxyntic gland) - HCl + intrinsic factor
Suface mucous cells - mucus
Chief cells - pepsinogen
G cells (in antrum) - gastrin

Question 9

How is acid secreted in the stomach?

Answer 9

1. H+ + HCO3- produced from CO2 + H2O
2. H+ secreted into lumen by H+/K+ATPase pump
3. HCO3- moves out of cell across basolateral membrane via Cl- antiport
4. Cl- diffuses into lumen via Cl- channel

Question 10

What stimulates acid secretion?

Answer 10

ACh - released near parietal cells from peripheral nerves
Gastrin - secreted from G cells, travels in blood to parietal cells.
Histamine - secreted from ECL cells, diffuses into parietal cells.

Gastrin & ACh cause histamine release.

Question 11

What inhibits acid secretion?

Answer 11

Somatostatin - inhibits gastrin & histamine release, inhibits proton pump on parietal cells
Prostaglandins - inhibits proton pump

Question 12

What is the purpose of mucus in the stomach?

Answer 12

It forms a gel to act as a gastric mucosal barrier against acid, proteolytic enzymes & mechanical damage

Question 13

What are the relations of the stomach?

Answer 13

Diaphragm, spleen, L. kidney, pancreas, L. colic flexure, transverse colon

Question 14

What is the nerve supply to the stomach?

Answer 14

Splanchnic nerve

Vagus nerve

Question 15

What is the blood supply to the stomach?

Answer 15

Short gastric
L & R gastroepiploic
Gastroduodenal
Superior pancreaticoduondenal

Question 16

What is the lymphatic drainage of the stomach?

Answer 16

Thoracic duct –> L. subclavian vein –> Subclavicular nodes
(Virchow’s nodes)