Gastric Physiology

Question 1

Organisation of the stomach

Answer 1

Corpus -> secretes acid; ‘stores’ bulk of a meal
Antrum -> secretes gastrin; grinds food
Both -> secrete pepsinogen and mucus

Question 2

Cells of the gastric (corpus) epithelium

Answer 2

Surface epithelial cells
Proliferating cells
Parietal cells
Enterochromaffin-like cells
D-cells
Chief cells

Question 3

Role of surface epithelial cells in the corpus

Answer 3

Protection from acid

Question 4

Lifetime of most gastric cells

Answer 4

2-3 days

Question 5

D-cells

Answer 5

Link to negative feedback loop

Question 6

Chief cells

Answer 6

Make and secrete pepsinogen, responsible for digesting proteins

Question 7

Acid secretion by parietal cells - 5 processes

Answer 7

(Nb - all processes happen at the same time)
Proton pump(H+/K+ATPase)
2. K+channel
3. Cl- channel
4. Sodium pump
5. Cl-/HCO3- exchanger

Question 8

Proton pump

Answer 8

Moves H+ out
Requires ATP
Builds approx. 1 million fold conc. gradient across membrane

Question 9

Where do the H+ ions come from?

Answer 9

Carbonic anhydrase in the cell

Question 10

K+ channel

Question 11

Cl- channel

Answer 11

HCl dissociated into H+ and Cl- via ** on the baso-lateral surface