GI 1

Question 1

4 layers of the GI tract

Answer 1

Mucosa (epithelium, lamina properia, muscularis mucosae)
Submucosa
Muscularis externa
Serosa

Question 2

Paneth cells

Answer 2

Secrete antibacterial peptides

Question 3

2 sources of innervation of the GI tract

Answer 3

Intrinsic (enteric nervous system - by nerve plexuses of the gut wall)
Extrinsic (Autonomic NS)

Question 4

2 plexuses in the enteric NS

Answer 4

Submucosal plexus (controls epithelium and GI blood flow)
Myenteric plexus (controls muscles)

Question 5

3 types of neurons in the enteric plexuses

Answer 5

Sensory
Motor
Interneurons

Question 6

Acetylcholine

Answer 6

Excitatory
Contraction of smooth muscle, relaxation of sphincters
Increased salivary, gastric, and pancreatic secretions

Question 7

Norepinephrine

Answer 7

Inhibitory
Relaxation of smooth muscle, contraction of sphincters
Increased saliva secretion

Question 8

Gastrin

Answer 8

Produced by G-cells in the antrum of the stomach
Release is stimulated by ingestion of a meal, small peptides and amino acids in the stomach, and distension
Stimulates gastric acid secretion from parietal cells, and growth of gastric mucosa
Inhibited by increased acidity of the stomach

Question 9

Secretin

Answer 9

Secreted by S cells of the duodenum
Release is stimulated by the entry of gastric juice into the small intestine
Causes release of bicarb to buffer the acidic stomach contents

Question 10

Cholecystokinin

Answer 10

Secreted by I cells in the duodenum and jejunum
Release is stimulated by fats, fatty acids, and monoglycerides in the intestine (also proteins, amino acids, and peptide releasing factors)
Causes the release of bile from gall baldder

Question 11

Motilin

Answer 11

Controls the pattern of smooth muscle contractions in the upper GI

Question 12

Glucose-dependent insulinotropic peptide (GIP)

Answer 12

Secreted from K cells in the first part of the small intestine
Enhances the release of insulin in response to infusions of glucose

Question 13

Glucagon-like peptide 1

Answer 13

Enhances the release of insulin in response to glucose
Suppresses secretion of glucagon
Used in diabetes therapy

Question 14

Glucagon-like peptide 2

Answer 14

Increases the size of the villi

Question 15

Ghrelin

Answer 15

Released from stomach
Stimulates appetite and feeding
Increased plasma concentration during fasting and just before meals
Target for anti-obesity treatment

Question 16

3 mechanisms of communication in the gut

Answer 16

Neurocrine
Paracrine
Endocrine

Question 17

6 types of cells in the small intestine epithelium

Answer 17

Villus absorption cells
Enteroendocrine cell
Goblet
Paneth
Stem cell
Undifferentiated crypt cell

Question 18

What cell type is missing in the large intestine that is present in the small?

Answer 18

Paneth cells

Question 19

Sensory neurons respond to which 4 stimuli?

Answer 19

Osmotic
Mechanical
Thermal
Chemical