Enzymes, Cofactors, Hormones, Vitamins and Their Functions

Question 1

Glucagon

Answer 1

Stimulates glycogenolysis by hepatocytes, thus elevating blood glucose levels.

Question 2

Somatostatin

Answer 2

Inhibits release of hormones by enteroendocrine cells locally

Question 3

Serotonin & Substance P (by EC cells)

Answer 3

Increases peristaltic movement

Question 4

Histamine

Answer 4

Stimulates HCl secretion

Question 5

Gastrin

Answer 5

Stimulates HCl secretion, gastric motility, and proliferation of regenerative cells

Question 6

Glicentin

Answer 6

Stimulates hepatocyte glycogenolysis, thus elevating blood glucose levels

Question 7

Cholecystokinin

Answer 7

33 amino acid peptide, Stimulates release of pancreatic hormone and contraction of gall bladder

Question 8

Gastric inhibitory peptide

Answer 8

Inhibits HCl Secretion

Question 9

Motilin

Answer 9

Increases intestinal peristalsis

Question 10

Neurotensin

Answer 10

Increases blood flow to the ileum and decreases peristaltic action of small and large intestines

Question 11

Pancreatic polypeptide

Answer 11

self-regulate pancreatic secretion activities (endocrine and exocrine); it also has effects on hepatic glycogen levels and gastrointestinal secretions.

Question 12

Secretin

Answer 12

Stimulates release of bicarbonate-rich fluid from the pancreas

Question 13

Vasoactive Intestinal Peptide

Answer 13

Increases peristaltic action of small and large intestines and stimulates elimination of water and ions by GI tract.

Question 14

Defensins

Answer 14

Antibacterial peptides

Question 15

Trypsin

Answer 15

Endopeptidase that breaks down arginine (R) and Lysine (K) residues on proteins into polypeptides.

Question 16

Chymotrypsin

Answer 16

Endopeptidase that breaks down proteins at aromatic residues

Question 17

Elastase

Answer 17

Endopeptidase that breaks down proteins at neutral aliphatic amino acids

Question 18

Carboxypeptidases A and B

Answer 18

Exopeptidases that hydrolyze 1 amino acid at a time from the C-(carboxy) terminus of proteins and peptides.

Question 19

Triacylglycerol Lipase

Answer 19

triacylglycerol + H2O diacylglycerol + a carboxylate

Question 20

Enterokinase aka Enteropeptidase

Answer 20

Cleavage of trypsinogen into trypsin

Anchored to membranes of epithelial enterocytes

Question 21

Amylase

Answer 21

Degrades starch (amylose and amylopectin) to maltose, isomaltose, and a-Dextrins.

**Free glucose is never the direct product of amylase digestion

Synthesized in active form in pancreas

Question 22

Ribonuclease

Answer 22

Cleaves RNA

Synthesized in active form in pancreas

Question 23

Maltase

Answer 23

Breaks maltose into glucose

Membrane anchored enzyme on apical enterocyte surface

Question 24

Isomaltase

Answer 24

Break isomaltose into glucose

Membrane anchored enzyme on apical enterocyte surface

Question 25

Intrinsic Factor

Answer 25

Required for absorption of Vitamin B12

Released by parietal cells

Question 26

Gastrin Releasing Peptide (GRP)

Answer 26

Elicits gastrin release and regulates gastric acid secretion and enteric motor function.

post-ganglionic fibers of the vagus nerve that innervate the G cells of the stomach release GRP, which stimulates the G cells to release gastrin.

Question 27

Lingual Lipase

Answer 27

Digests fat to monoglycerides and fatty acids

Question 28

Pepsin

Answer 28

Endopeptidase that breaks down aromatic residues on protein to polypeptides in stomach

Question 29

Colipase

Answer 29

A protein that helps anchor lipase to the surface of fat droplets

Question 30

Phospholipase A2

Answer 30

hydrolyzes the bond between fatty acids and the second carbon group of glycerol, releasing arachidonic acid and lysophospholipids.

Question 31

Cholesterol Ester Hydrolase

Answer 31

catalyzes the hydrolysis of sterol esters into their component sterols and fatty acids.

Synthesized in acinar cells of pancreas

Question 32

Sucrase-isomaltase (SI)

Answer 32

Breaks down a-Limit dextrin (branch points of starch) to Glucose

Question 33

Maltase-Glucoamylase (MGA)

Answer 33

Breaks down Maltotriose (linear forms of starch) to Glucose

Question 34

Lactase

Answer 34

Breaks down Lactose to Glucose

Question 35

Sucrase

Answer 35

Breaks down Sucrose to Glucose

Question 36

Aminopeptidase

Answer 36

Brush Border exoprotease that removes one amino acid at a time from N (amino) terminus

Question 37

Dipeptidyl Aminopeptidase

Answer 37

Brush Border exoprotease that removes TWO amino acids at a time from N (amino) terminus

Question 38

Dipeptidase

Answer 38

Brush Border Protease that converts dipeptides to amino acids

Question 39

Lactoferrin

Answer 39

primary role is to sequester free iron, and in doing so remove essential substrate required for bacterial growth.

widely represented in various secretory fluids, such as milk, saliva, tears, and nasal secretions.

Question 40

Mucins

Answer 40

key component in most gel-like secretions, serving functions from lubrication to cell signalling to forming chemical barriers.

Question 41

Prostaglandin E2

Answer 41

enhance secretion of gastroduodenal mucous, stimulate bicarbonate secretion, maintain mucosal blood flow during periods of potential injury

Question 42

Prostacyclin

Answer 42

Protects mucosa, synergistic with Prostaglandin E2

Question 43

Monitor Peptide

Answer 43

Stimulates release of cholecystokinin