Reg. GI Fxn

Question 1

Five Functions of the gut

Answer 1

motility
secretion
digestion
absorption
storage

Question 2

Paracrine definition

Answer 2

peptides secreted from cells with subsequent diffusion through the interstitial space to contact and affect other cells

Question 3

Autocrine definition

Answer 3

secretions of a given cell modify or regulate functions of the same cell

Question 4

Neurocrine definition

Answer 4

secretion by enteric neurons of neuromodulators or regulatory peptides that affect nearby muscle cells, glands, or blood vessels.

Question 5

Secretin: production site

Answer 5

duodenum and upper jejunum; S cells

Question 6

Secretin: Action

Answer 6

stimulates HCO3- secretion and inhibits acid secretion (nature’s anti-acid). Stimulates exocrine pancreatic and biliary secretions of water, bicarb. gastric mucus and pepsinogen; endocrine pancreatic secretions of insulin, glucagon, and somatostatin; and pancreatic growth
Inhibits gastric acid secretion, motility of intestine and gastric mucosal growth.

Question 7

Secretin: Release stimulus

Answer 7

Gastric acid, fat, protein, bile acids, and herbal extracts

Controlled by action of hormones: CCK, hormonal-neuronal control (CCK-vagal)

Question 8

Gastrin: prod. site

Answer 8

stomach (pylorus and antrum) and duodenum G cells

Question 9

Gastrin: Action

Answer 9

Stimulates acid secretion and growth of stomach epithelium (cancer marker)

Question 10

Gastrin: Release stimulus

Answer 10

Protein, increased high gastric acidity, gastric distention

Question 11

Cholecystokinin: Production site

Answer 11

Duodenum, jejunum, ileum; endocrine I (“i”) cells and enteric neurons of duodenum and jejunum

Question 12

Cholecystokinin: Action

Answer 12

Stimulates pancreatic enzyme secretion and gallbladder contractions; inhibits food intake and gastric emptying

Question 13

Cholecystokinin: Release stimulus

Answer 13

Fats and protein

Question 14

Gastric inhibitory polypeptide: Production site

Answer 14

duodenum and jejunum

Question 15

Gastric inhibitory polypeptide: action

Answer 15

inhibits gastric secretions and emptying and stimulates insulin secretion. Slows movement of ingesta particularly from stomach to intestine.

Question 16

Gastric inhibitory polypeptide: release stimulus

Answer 16

fat and glucose (glu. in duodenum)

Question 17

Motilin: Production site

Answer 17

M cells of duodenum and jejunum (jejunum lesser extent than duod.)

Question 18

Motilin: Action

Answer 18

induction/regulation of phase III of the MMC (migrating motor complex) during fasting (digestive state). Works on both muscles and nerves. Stimulates gastric emptying between meals and secretion of pepsinogen (protein digesting enzyme)

Question 19

Motilin: Release stimulus

Answer 19

Acetylcholine

Question 20

Cholinergic neurons are typically _________ to gut? inhibit or stim? Molecule?

Answer 20

stimulatory, Acetycholine

Question 21

adrenergic neurons are typically __________ to gut? inhibit or stimulatory? Molecule?

Answer 21

Inhibitory: adrenaline/epinephrine

Question 22

Gastrin forms

Answer 22

G-17 (90%) and G-34 (10%, duodenum)

Question 23

Gastrin binds to ____________

Answer 23

CCK-2 receptor, g-protein coupled receptor. Causes stimulation of gastric acid secretion and hyperplasia of enterochromaffin-like cells.

Question 24

Gastrin & histamine =?

Answer 24

Gastrin increases acid secretion indirectly by stimulation of histamine release from ECL which can activate H2 receptors on acid secreting gastric parietal cells.

Question 25

CCK receptors and locations

Answer 25

CCK-1 alimentary, CCK-2 brain

Question 26

Aldosterone: definition

Answer 26

steroid hormone (mineralocorticoid) secreted by outer zone glomerulosa of adrenal cortex after low-salt diet, angiotensin, adrenocorticotropic hormone, or high potassium levels.

Question 27

Aldosterone: function

Answer 27

act on distal convoluted tubules and collecting ducts of the kidney causing secretion of K+ and reabsorption of Na+ and H2O.

Question 28

Aldosterone: GI fxn.

Answer 28

stimulates sodium and water reabsorption from the gut and salivary glands in exchange with K+ ions. Species dependent: water and Na+ reabsorption in proximal colon and decrease absorption in distal colon.