MA - Digestive System II

Question 1

What are some features of the smooth muscle found in the GI tract?

Answer 1

• Involuntary
• Non-striated
• Contain gap junctions (communicate with surrounding cells)

Question 2

What are the two types of contraction in the gut?

Answer 2

Tonic - means that muscle contains mostly slow-contraction, long-duralibity fibers

Phasic - means that muscle contains mostly quick-contraction, hi-power, short-duralibity fibers

Question 3

What does the Migrating Motor Complex do?

Answer 3

Designed to move matter through the tract

Question 4

What does the enteric nervous system control?

Answer 4

Motility

Question 5

What are 3 GI-associated reflexes?

Answer 5

Short reflexes- Originate in the ENS and are integrated without the CNS

Long reflexes- Integrated into the CNS

Cephalic reflexes- Long reflexes that originate in the CNS

Question 6

Where are GI secretions released? (3)

Answer 6

• Blood
• Lumen
• Neigbouring Cells (Paracrine)

Question 7

What are the 3 main secretions of the pancreas?

Answer 7

1. Zymogens
2. Enzymes
3. Bicarbonate

Question 8

What cell produces bile?

Answer 8

Hepatocytes
* bile → bile canaliculi → bile duct

Question 9

How and where are carbohydrates digested?

Answer 9

• Broken down into monosaccharides

Absorption into the small intestine
* Requires transporters to cross from lumen into blood

Question 10

How are proteins digested?

Answer 10

Endopeptidases- Digests internal bonds within the protein structure

Exopeptidases- Releases amino acids

Question 11

How does protein size affect absorption?

Answer 11

Amino acids:
* Na+ cotransport

Di/tri-peptides:
* H+ cotransport

Small peptides:
* Endo/exocytosis, transcytosis across cell membrane

Question 12

How are lipids digested? (3)
(TGs, Cholestrol esters, Phospholipids)

Answer 12

TGs are cleaved to mono/diacylglycerides and FFAs

Cholestrol esters cleaved to AAs and cholesterol

Phospholipids cleaved by phospholipase A to fatty acids