Nervous and Endocrine Control

Question 1

GIT Sympathetic nervous control

Effects and Mediators

Answer 1

• Decrease motility (NE)
• Decrease secretions (NE)
• Constriction of sphincters (NE)

Question 2

GIT Parasympathetic control

Effects and Mediators

Answer 2

• Increase motility and secretions (ACh)
• Relaxation of sphincters (VIP through NO)
• Increase gastrin secretion (GRP by stimulating G cells)

Question 3

Gastrin

Source

Answer 3

G cells of stomach antrum and duodenum

Question 4

Somatostatin

Source

Answer 4

D cells of pancreatic islets and GI mucosa

Question 5

Cholecystokinin (CCK)

Source

Answer 5

I cells of duodenum and jejunum

Question 6

Secretin

Source

Answer 6

S cells of duodenum

Question 7

Glucose-dependent insulinotropic peptide (GIP)

Source

Answer 7

K cells of duodenum and jejunum

Question 8

Motilin

Source

Answer 8

Small intestine

Question 9

Vasoactive intestinal polypeptide (VIP)

Source

Answer 9

Parasympathetic ganglia in sphincters, gallbladder and small intestine

Question 10

Ghrelin

Source

Answer 10

Stomach

Question 11

Gastrin

Stimulants

Answer 11

• Increased by stomach distention/alkalinization, amino acids, peptides and vagal stimulation via gastrin releasing peptide (GRP)
• Decreased by pH < 1.5

Question 12

Somatostatin

Stimulants

Answer 12

• Increased by acid

- Decreased by vagal stimulation

Question 13

Cholecystokinin (CCK)

Stimulants

Answer 13

Increased by fatty acids and amino acids

Question 14

Secretin

Stimulants

Answer 14

Increased by acid and fatty acids in duodenal lumen

Question 15

Glucose-dependent insulinotropic peptide (GIP)

Stimulants

Answer 15

Increased by fatty acids, amino acids and oral glucose

Question 16

Motilin

Stimulants

Answer 16

Increased in fasting state

Question 17

Vasoactive intestinal polypeptide (VIP)

Stimulants

Answer 17

• Increased by distention and vagal stimulation

- Decreased by adrenegic input

Question 18

Ghrelin

Stimulants

Answer 18

• Increased in fasting state

- Decreased by food

Question 19

Gastrin

Action

Answer 19

• Increases gastric H+ secretion and motility

- Increases growth of gastric mucosa

Question 20

Somatostatin

Action

Answer 20

• Decreases gastric acid and pepsinogen secretion
• Decreases pancreatic and small intestinal fluid secretion
• Decreases gallbladder contraction
• Decreases insulin, glucagon and most other hormones release including growth hormone

Question 21

Cholecystokinin (CCK)

Action

Answer 21

• Increases pancreatic secretions
• Increases gallbladder contraction
• Causes relaxation of sphincter of Oddi
• Decreases gastric emptying

Question 22

Secretin

Action

Answer 22

• Increases pancreatic HCO3- secretion (to neutralize gastric acids and allow pancreatic enzymes to function)
• Increases bile secretion
• Decreases gastric motility and acid secretion

Question 23

Glucose-dependent insulinotropic peptide (GIP)

Action

Answer 23

• Exocrine: decreases gastric motility and acid secretion

- Endocrine: Increases insulin release

Question 24

Motilin

Action

Answer 24

Produces migrating motor complexes (MMCs)

Question 25

Vasoactive intestinal polypeptide (VIP) | Action

Answer 25

- Increases intestinal water and electrolyte secretion | - Increases relaxation of intestinal smooth muscles and sphincters

Question 26

Ghrelin | Action

Answer 26

Increases appetite

Question 27

Glucagon-like peptide (GLP) | Source

Answer 27

Duodenal cells

Question 28

Glucagon-like peptide (GLP) | Stimulants

Answer 28

Increased by carbohydrates

Question 29

Glucagon-like peptide (GLP) | Action

Answer 29

- Decreases gastric motility and acid secretion | - Decreases glucagon release

Question 30

Hormones that increases insulin release

Answer 30

- Gastric inhibitory peptide (GIP) | - Glucagon-like peptide (GLP)

Question 31

Gastrin | Notes

Answer 31

- Increased by chronic PPI use - Increased in chronic gastritis - Increased so much in Zollinger-Ellison syndrome (gastrinoma)

Question 32

Somatostatin | Notes

Answer 32

Octreotide is an analog that is used in treatment of - Acromegaly - Carcinoid syndrome - Variceal bleeding

Question 33

Cholecystokinin (CCK) | Notes

Answer 33

Acts on neural muscarinic pathways to cause pancreatic secretion

Question 34

Glucose-dependent insulinotropic peptide (GIP) | Notes

Answer 34

Oral glucose load lead to increase insulin compared to IV glucose due to GIP secretion

Question 35

Motilin | Notes

Answer 35

Motilin receptor agonists like erythromycin are used to stimulate intestinal peristalsis

Question 36

Vasoactive intestinal polypeptide (VIP) | Notes

Answer 36

VIPoma (non-alpha, non-beta islet cell pancreatic tumor that secrets VIP) will cause Watery Diarrhea, Hypokalemia and Achlorhydria (WDHA syndrome)

Question 37

Ghrelin | Notes

Answer 37

- Increased in Prader-Willi syndrome | - Decreased after gastric bypass surgery