Digestion of proteins by gastric juice.

Question 1

What is gastric juice?

Answer 1

a very acidic, thin almost colourless liquid, secreted by the glands of the stomach. (pH 1-3)

Question 2

What are essential constituents of gastric juice?

Answer 2

Digestive enzymes:
pepsin/chymosin
HCL
mucus

Question 3

Function of pepsin?

Answer 3

Converts protein into simpler moree easily absorbed substances.

Question 4

Inactive precursor of pepsin?

Answer 4

Pepsinogen

Question 5

What is pepsinogen?

Answer 5

Precursor of pepsin. Stored in stomach wall, converted to pepsin by HCl during digestion.

Question 6

Secretory product and function of mucous cells?

Answer 6

alkaline mucus–> secretion after mechanical stimuli by stomach content
protects muscosa against pepsin & HCl

Question 7

Secretory product and function of chief cells?

Answer 7

Production of pepsinogen, supported by acetylchline and gastrin.

Question 8

Secretory product and function of Parietal cells?

Answer 8

HCl –> pepsin activation
CT breakdown, destruction of MOs.
supported by acetylcholine, gastrin, histamine
(Production of intrinsic factor important for B12 absorption)

Question 9

Secretory product and function of enterochromaffine like cells (ECL)?

Answer 9

Production of histamine stimulated by acetylcholine and gastrin
–> stimulates parietal cells

Question 10

Secretory product and function of G cells?

Answer 10

Production of gastrin supported by acetylcholine and protein products.
–> stimulates chief, ECL cells

Question 11

Secretory product and function of D cells?

Answer 11

Production of somatostatin supported by acids.

–> inhibits parietal, G and ECL cells.

Question 12

What does digestive enzymes need for proper function?

Answer 12

Good conditions in temperature and pH.