Control Of The Digestive System

Question 1

What is the pancreatic nerve supply?

Answer 1

3 types greater splanchnic, lesser splanchnic and least splanchnic
Symp postgang fibres: emanate from celiac and superior messnreric plexuses
Para pregang fibres: distributed by branches of the vagi coursing down antral-duo region
- vagal fibres term at acini and islets or at the intrinsic cholinergic nerve of pancreas

Question 2

How does the pancreas understand to secrete enzymes and bicarb?

Answer 2

Acid and fat/prot from stomach enter the duo and interact with I and C cells which secrete CCK and secretin
CCK causes pancreatic enzyme secretion
Secretin causes pancreatic bicarb secretion

Question 3

What are the control mechanisms of small intestinal digestion?

Answer 3

Food enters the SI, interacts with I cells to secrete CCK that causes defeated gastric emptying and food intake, and increases enzymes, bile salts and electrolytes that help with digestion and absorption

Question 4

What is CCKs effect on digestion?

Answer 4

It activates the CNS to inhib food intake and gastric emptying and via the circ it stinks the gall bladder and pancreas

Question 5

What innervates the acinar cells and duct cells?

Answer 5

The vagus nerve

Question 6

How does the Ca get released to cause enzyme release?

Answer 6

CCK binds the recep, secondary messenger causes the RyR ch to release Ca
ACh binds recep, secondary messenger (IP3), act IP3R to release Ca

Question 7

What are the brain centres that control food intake?

Answer 7

Hypothalamic lesions: - satiety centres (ventromedial, paraventircular and hypothalamic nuc)

Question 8

How does leptin affect digestion?

Answer 8

Adipose tissue secretes leptin, this activates the POMC, which activates the effector nuc to reduce food intake
The pancreas secretes insulin and inhibs NPY/agrp, which inhibs the effector nuc and increases meta
All of these things found in the arcuate nuc

Question 9

How does leptin affect food intake

Answer 9

Inhibition:
- activates POMC and CART in the arcuate. If to inhib the lateral hypothal (hunger) and activates the paraventricular nuc (satiety)

Question 10

How does ghrelin affect food intake?

Answer 10

Activation:

• ghrelin inhibs the POMC and CART
• activates the lateral hypothal (hunger) and inhibs the paraventricular nuc (satiety)

Question 11

What is the function of b2-adr receps?

Answer 11

Relaxation of gut SM