Gut Motility

Question 1

Effect of CCK on Gallbladder, Pancreas, Stomach, Sphincter of Oddi:

Answer 1

Gallbladder: Contraction
Pancreas: Acinar secretion
Stomach: Reduced emptying
Sphincter of Oddi: relaxation

Question 2

What causes release of CCK?

Answer 2

Ach
CCK-releasing peptide
Gastrin releasing peptide

Question 3

What inhibits CCK release?

Answer 3

Trypsin by degrading CCK-RP

Question 4

Where is secretin produced?

Answer 4

In the duodenum by S cells

Question 5

When is secretin released?

Answer 5

In response to low pH and polypeptides

Question 6

Effect of increased Ca++ intracellularly:

Answer 6

Contraction

Question 7

Effect of increased cAMP intracellularly:

Answer 7

Relaxation

Question 8

Effect of Ouabain:

Answer 8

Inactivates the Na/K pump to causing a buildup of Na intracellularly

Question 9

What are the effects of cAMP and Ca++ on intestinal secretions?

Answer 9

Increase of cAMP and Ca cause an increase in secretions by stimulating epithelial cells to transport ions in to the lumen (causing the rhea)

Question 10

How does the NaCl transport process drive the absorption of short-chain fatty acids in the colon?`

Answer 10

Using the sodium-monocarboxylate transporter (SMCT) it uptakes SCFA and Na (Na/K pump pumps out the Na)

Question 11

What is needed for expression of the SMCT?

Answer 11

SMCT1 gene (reduction results in some colon cancers)

Question 12

What layer are the Interstitial cells of Cajal found?

Answer 12

Muscularis externa

Question 13

How does SM action potentials differ from other muscle types?

Answer 13

They are much longer resulting in slow wave contractions

Question 14

What is the effect of epi and norepi on the SM AP?

Answer 14

It causes a hyperpolarization so that Ca channels cannot be activated and muscle relaxes

Question 15

What is the effect of VIP and NO on SM?

Answer 15

Relaxation

Question 16

Effect of Ach and substance P on SM?

Answer 16

Contraction

Question 17

What does a SM look like at a rest?

Answer 17

Has slow wave contractions

Question 18

What does the SM AP look like when food is ingested?

Answer 18

Slow wave with spikes on top of them due to Ach and Sub P release

Question 19

What is the muscle composition of the esophagus?

Answer 19

Proximal portion is skeletal muscle

Distal portion is smooth muscle

Question 20

Why does the LES have increased pressure?

Answer 20

To stop gastric acid from coming out to the esophagus

Question 21

What nerve causes relaxation of the esophagus?

Answer 21

Vagus (releasing NO and VIP)

Question 22

How does a bolus move?

Answer 22

Dorsal vagus complex releases NO at the distal end of the bolus and Ach at the proximal end

Question 23

What does residual food cause?

Answer 23

A secondary peristaltic event to clear the food

Question 24

What occurs when the stomach is full?

Answer 24

Stretch receptors are activated causes a release of CCK that acts on DVC releasing NO and VIP to cause relaxation

Question 25

Where in the stomach are the pacemaker cells found?

Answer 25

Greater curvature (where the slow waves are generated)

Question 26

What occurs during times of fasting?

Answer 26

A very slow wave of muscle contraction moves from the stomach all the way down to the end of the SI; does not occur in the colon (would cause defecation)

Question 27

What are the muscle compositions of the anal sphincters?

Answer 27

Internal: Smooth muscle
External: Skeletal muscle

Question 28

What occurs in the defecation reflex?

Answer 28

Sensing the rectum is full an impulse is sent to relax the internal anal sphincter

Question 29

What does CCK act on?

Answer 29

Dorsal vagal complex to facilitate gallbladder contraction and relaxation of the Sphincter of Oddi

Question 30

What is achalasia?

Answer 30

The LES is contracted/not relaxed so esophagus gets distended