GI Physiology

Question 1

What organs make up the GI tract?

Answer 1

Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anal canal

Question 2

What are the accessory organs of the GI system?

Answer 2

Teeth, tongue, salivary glands, liver, gallbladder, pancreas

Question 3

What are the four histologic layers of the GI tract?

Answer 3

Mucosa, submucosa, muscularis externa, serosa/adventitia

Question 4

What is the function of the mucosa?

Answer 4

Absorption, secretion of mucus, enzymes, and hormones

Question 5

Which plexus is found in the submucosa?

Answer 5

Submucosal (Meissner’s) plexus

Question 6

What controls peristalsis in the muscularis externa?

Answer 6

Myenteric (Auerbach’s) plexus

Question 7

What is the difference between serosa and adventitia?

Answer 7

Serosa reduces friction in intraperitoneal organs; adventitia binds retroperitoneal organs

Question 8

Which germ layer forms the epithelial lining of the GI tract?

Answer 8

Endoderm

Question 9

Which part of the oral cavity is lined by keratinized epithelium?

Answer 9

Superior tongue surface and hard palate

Question 10

Which enzyme starts carbohydrate digestion in the mouth?

Answer 10

Salivary amylase

Question 11

What enzyme does the tongue secrete to digest lipids?

Answer 11

Lingual lipase

Question 12

Which salivary gland produces only serous secretions?

Answer 12

Parotid gland

Question 13

What is the function of the esophagus?

Answer 13

Transports food to the stomach via peristalsis

Question 14

Which muscles control the voluntary and involuntary phases of swallowing?

Answer 14

Voluntary: skeletal muscles; Involuntary: controlled by CN IX and X

Question 15

What are the three muscular layers of the stomach?

Answer 15

Inner oblique, middle circular, outer longitudinal

Question 16

Which cells secrete hydrochloric acid and intrinsic factor?

Answer 16

Parietal cells

Question 17

What activates pepsinogen to pepsin?

Answer 17

Stomach acid (HCl)

Question 18

Which stomach cells secrete mucus to protect epithelium?

Answer 18

Foveolar and mucous neck cells

Question 19

Where does most nutrient absorption occur?

Answer 19

Small intestine

Question 20

Which part of the small intestine is primarily responsible for absorption?

Answer 20

Jejunum

Question 21

What is the role of villi and microvilli?

Answer 21

Increase surface area for absorption

Question 22

What is the function of Brunner glands?

Answer 22

Produce bicarbonate to neutralize stomach acid in the duodenum

Question 23

What is the function of bile?

Answer 23

Emulsify fats for digestion

Question 24

Which enzymes does the pancreas secrete for digestion?

Answer 24

Trypsinogen, chymotrypsinogen, amylase, lipase, etc.

Question 25

What is the primary function of the large intestine?

Answer 25

Absorb water and electrolytes; form feces

Question 26

What vitamin is produced in the large intestine?

Answer 26

Vitamin K

Question 27

What signals the defecation reflex?

Answer 27

Stretch receptors in the rectum

Question 28

Which cells secrete Gastrin and where are they located?

Answer 28

G-cells; primarily in the stomach (pyloric antrum) and also in the upper small intestine

Question 29

What is the function of Gastrin?

Answer 29

Stimulates secretion of HCl by parietal cells and gastric motility

Question 30

Which cells secrete Cholecystokinin (CCK) and where?

Answer 30

I-cells; located in the duodenum and jejunum

Question 31

What is the function of CCK?

Answer 31

Stimulates gallbladder contraction and pancreatic enzyme secretion

Question 32

Which cells secrete Secretin and where?

Answer 32

S-cells; in the duodenum

Question 33

What is the function of Secretin?

Answer 33

Stimulates pancreatic bicarbonate secretion and inhibits gastric acid secretion

Question 34

Which cells secrete Gastric Inhibitory Peptide (GIP) and where?

Answer 34

K-cells; in the duodenum and jejunum

Question 35

What is the function of GIP?

Answer 35

Inhibits gastric acid secretion and stimulates insulin release

Question 36

Which cells secrete Somatostatin and where?

Answer 36

D-cells; found in the stomach, small intestine, and pancreas

Question 37

What is the function of Somatostatin?

Answer 37

Inhibits secretion of many GI hormones including gastrin

Question 38

Which cells secrete Motilin and where?

Answer 38

M-cells; in the duodenum and jejunum

Question 39

What is the function of Motilin?

Answer 39

Increases gastrointestinal motility during fasting (migrating motor complex)

Question 40

Which cells secrete Vasoactive Intestinal Peptide (VIP) and where?

Answer 40

Enteric neurons (parasympathetic ganglia) in the small intestine

Question 41

What is the function of VIP?

Answer 41

Relaxes smooth muscle, increases intestinal secretion, and dilates peripheral blood vessels

Question 42

Which cells secrete Pro-glucagon-derived peptides like GLP-1 and where?

Answer 42

L-cells; in the distal ileum and colon

Question 43

What is the function of GLP-1?

Answer 43

Enhances insulin secretion, inhibits glucagon release, and slows gastric emptying