Stomach

Question 1

Describe the different types of signalling molecule used in the stomach and their mode of action. (3)

Answer 1

Hormones: peptides released from endocrine cells that travel through the blood to their target
Paracrine: locally acting
Neurocrine: peptides released by neurones after an action potential.

Question 2

Gastrin: cell secreted

Answer 2

G cells stomach antrum

Question 3

CCK: cell secreted

Answer 3

I cells duodenum and jejunum.

Question 4

Secretin: cell secreted

Answer 4

S cells duodenum

Question 5

Somatostatin: cell secreted

Answer 5

D cells

Question 6

Gastrin: actions

Answer 6

Increase gastric acid secretion by increasing parietal cell action.

Question 7

Gastrin: stimulation and inhibition

Answer 7

Amino acids, stretch receptors, vagus nerve all stimulate G cells to produce Gastrin.
Somatostatin inhibits G cells.

Question 8

CCK: actions

Answer 8

Increases gallbladder and pancreatic secretions to be released intot he duodenum

Question 9

CCK: stimulation

Answer 9

Fat and protein in stomach

Question 10

Secretin: actions

Answer 10

Increases HCO3- from pancreas and gallbladder.

Decreases gastric acid

Question 11

Describe Gastrin inhibitory peptide

Answer 11

Same as secretin

Decreases gastric acid

Question 12

Explain why the stomach can distend so much. (1)

Answer 12

Has rugae which allow for large amounts of distension.

Question 13

Somatostatin: actions.

Answer 13

Inhibitory to gastric acid and pancreatic secretions.

Question 14

Parietal cells: actions

Answer 14

HCl and intrinsic factor

Question 15

Enterochromaffin like cells: action

Answer 15

Histamine

Question 16

Parietal cells: stimulation

Answer 16

Vagus nerve, histamine, Gastrin.

Question 17

Describe the structure of gastric glands/pits. (6)

Answer 17

U shaped, with gastric pits at the top with surface muscles cells.
Get deeper and enter gland which has neck mucous cells, parietal cells, chief cells and enteroendocrine cells

Question 18

Describe the inhibition of HCl production. (7)

Answer 18

Essentially an inhibition of G cells.
When food leaves stomach pH drops because food is a buffer.
Low pH activates D cells
D cells release somatostatin
Somatostatin inhibits G cells and ECL cells
Inhibits Gastrin and histamine.
No more acid secretion.

Question 19

Chief cells: action

Answer 19

Release pepsinogen

Question 20

Chief cells: stimulation

Answer 20

Gastrin and vagus nerve.

Question 21

Describe the cephalic phase of digestion. (4)

Answer 21

Parasympathetic of vagus stimulates G and parietal cells to make acid and Gastrin on sight, smell, taste of food.

Question 22

Describe the gastric phase of digestion. (9)

Answer 22

Distension of stomach - vagus - parietal and G cells produce HCl and Gastrin
Amino acid presence - G cells
Food acts as a buffer - removes inhibition on Gastrin production - more Gastrin - more histamine - more acid.

Question 23

Describe the intestinal phase of digestion. (4)

Answer 23

Empty stomach increases somatostatin which inhibits G cells - reduces vagus - chyme stimulates CCK and secretin.

Question 24

Explain how the problems of the stomach acid digesting the stomach is sorted. (3)

Answer 24

Stomach releases mucus with HCO3- from mucus cells.
High turnover of epithelial cells
Prostaglandins maintain blood flow.

Question 25

Describe things that can breach the stomach. (3)

Answer 25

Alcohol - dissolves mucus layer
Helicobacter pylori
NSAIDs - inhibits prostaglandins.

Question 26

Describe the regions of the stomach. (5)

Answer 26

Cardia - enterance
Fundus - top, above enterance
Body - main bit, below enterance 
Antrum - bottom
Pylorus - exit.