GI enzymes

Question 1

gastrin (source, target, action)

Answer 1

Source: antrum of stomach
Target: parietal cell in stomach
Action: increase H+ secretion, increase pepsinogen secretion

34aa, 17 aa

Question 2

CCK (source, target, action)

Answer 2

Source: duodenum and jejunum
Target: pancreas and gallbladder
Action: increase enzyme secretion, increase contraction

33 aa

Question 3

secretin (source, target, action)

Answer 3

Source: duodenum
Target: pancreas ducts and bile ducts
Action: increase HCO3/fluid secretion by pancreatic/bile ducts

27 aa

Question 4

gastrin releasing peptide (GRP)

source, target, action

Answer 4

Source: vagal nerve endings
Target: antrum of stomach
Action: increase gastrin release

Question 5

somatostatin (source, target, action)

Answer 5

Source: stomach and duodenum
Target: stomach, pancreas, liver
Action: decrease gastrin release, decrease endocrine/exocrine secretions, decrease bile flow

Question 6

gastrin inhibitory peptide (GIP)

source, target, action

Answer 6

Source: duodenum and jejunum
Target: pancreas
Action: decrease fluid absorption

Question 7

as the digestive products are emptied into the small intestine it is important to maintain a ____ pH. How does this happen?

Answer 7

near neutral pH

Stomach acid is neutralized by HCO3– from the liver and pancreas.
• Inactivates pepsin
• Prevents acid-pepsin damage to duodenal mucosa
• Provides functional pH for pancreatic and enterocyte specific enzymes
• Increases solubility of bile acids and fatty acids

Question 8

SI enzymes, secreted or membrane-bound?

Answer 8

membrane bound

enterokinase
disaccharidases
peptidases