GIT Physiology AB

Question 1

Gastrin - which cells secrete this and where are the cells located?

Answer 1

G cells in the antrum of the stomach

Question 2

Gastrin - what stimulates secretion?

Answer 2

Food
High antral pH
Vagus nerve
Luminal peptides/amino acids

Question 3

Gastrin - what inhibits secretion?

Answer 3

Low antral pH

Somatostatin

Question 4

Gastrin - which cells does it target?

Answer 4

Parietal cells (H+)
D cells (somatostatin)

Question 5

Gastrin - what are the 3 major functions?

Answer 5

1. Increase HCL, pepsinogen and IF secretion
2. Increases gastric motility
3. Stimulates parietal cell maturation

Question 6

Cholecystokinine - which cells secrete this?

Answer 6

I cells in the proximal small bowel

Question 7

Cholecystokinine - what stimulates secretion?

Answer 7

Partially digested proteins and triglycerides

Question 8

Cholecystokinine - what are the 5 major functions?

Answer 8

1. Increased pancreatic enzyme secretion
2. Contraction of gallbladder
3. Relaxation of sphincter of oddi
4. Decreased gastric emptying
5. Induces satiety

Question 9

Somatostatin - which cells secrete this?

Answer 9

D cells in the stomach and pancreas

Question 10

Somatostatin - what stimulates secretion?

Answer 10

Fat, bile salts and glucose in the intestinal lumen

Question 11

Somatostatin - what are the major functions?

Answer 11

1. Decreases acid and pepsin secretion
2. Decreases gastrin secretion
3. Decreases pancreatic enzyme secretion
4. Decreases insulin and glucagon secretion
5. Inhibits trophic effects of gastrin
6. Stimulates gastric mucous production

Question 12

Secretin - which cells secrete this?

Answer 12

S cells in the upper small bowel

Question 13

Secretin - what stimulates secretion?

Answer 13

Acidic chyme, fatty acids

Question 14

Secretin - what are the 3 major function?

Answer 14

1. Increases secretion of bicarbonate-rich fluid from pancreas and hepatic duct cells
2. Decreases gastric acid secretion
3. Trophic effect on pancreatic acinar cells

Question 15

Vasoactive intestinal peptide - where is this secreted from?

Answer 15

Myenteric inhibitory motor neurons/submucosal neurons

Question 16

Vasoactive intestinal peptide - what stimulates secretion?

Answer 16

Neural stimulation

Question 17

Vasoactive intestinal peptide - what is the function?

Answer 17

1. Stimulates secretion by pancreas and intestines

2. Inhibits acid secretion

Question 18

Parietal cell - where is it located?

Answer 18

Body and fundus of stomach

Question 19

Parietal cell - what stimulates this cell and via which receptor?

Answer 19

Histamine - H2 receptor

Gastrin - CCK-B receptor

ACh - M3 receptor via vagus nerve

Question 20

Parietal cell - what does it secrete?

Answer 20

HCL

Intrinsic factor

Question 21

What are the causes of hypergastrinaemia?

Answer 21

Prolonged acid inhibition with PPI/H2RA - commonest
Atrophic gastritis - pernicious anaemia, H pylori
Vagotomy/SB resection

Rare: ZE syndrome, renal failure, hypercalcaemia

Artefactual: hyperlipidaemia

Question 22

The action of the brush border enzyme maltase results in the formation of what?

Answer 22

maltase: cleaves disaccharide maltose to glucose + glucose

Question 23

The action of the brush border enzyme sucrase results in the formation of what?

Answer 23

sucrase: cleaves sucrose to fructose and glucose

Question 24

The action of the brush border enzyme lactase results in the formation of what?

Answer 24

lactase: cleaves disaccharide lactose to glucose + galactose