Bile Secretions/Large Intestine

Question 1

Bile Salts

Answer 1

Addition of Na+ to bile acid; form cylindrical micelles to contain FAs, cholesterol, monogylcerides, etc.

Question 2

Bile Pigments

Answer 2

Bilirubin; soluble when conjugated in the liver and secreted from liver as salt glucuronide

Question 3

Bile Salt Reabsorption

Answer 3

Bile salts initially actively reabsorbed in the terminal ileum

Reabsorbed into liver from portal blood by Na+-cotransport and secreted across apical membrane via ATPase-dependent bile pump

*Reabsorption from portal blood dependent upon activity of Na+/K+-ATPase

Question 4

Bile-independent fraction of biliary secretion

Answer 4

Influenced by activity of secretin

Increases HCO3- and water

Question 5

Bile-dependent fraction of biliary secretion

Answer 5

Amount of bile secreted is directly related to the amount of bile reabsorbed

*Example: Increased secretion => Increased return => Decreased synthesis

Question 6

Actions of CCK on gall bladder (2)

Answer 6

1. Contracts smooth muscle

2. Relaxes sphincter of Oddi

Question 7

Cholelithiasis

Answer 7

A. Cholesterol (more common)
-Ppt. of cholesterol due to supersaturation

B. Pigment
-Unconjugated bilirubin ppts. w/ Ca2+

Question 8

Cholecystectomy

Answer 8

Performed for the treatment of gallstones; bile will empty slowly and continuously into the duodenum since there is no place for storage

*High-fat meals should be avoided

Question 9

Most common contraction in colon

Answer 9

Segmentation; partly responsible for appearance of haustra

Question 10

Rectal contractions

Answer 10

Segmental contractions greater here than in sigmoidal colon

=> Retrograde movement of fecal matter

Question 11

Rectosphincteric reflex

Answer 11

Contraction of the rectum and relaxation of the internal anal sphincter in response to fecal matter being forced into the rectum

Question 12

Hirschsprung’s Disease

Answer 12

Absence of inhibitory enteric nervous system in a part of the colon resulting in tonic constriction

=>Accumulation of contents proximal to this constriction causing severe constipation

Treatment= removal of segment of colon

Question 13

Responsible for movement of fecal material into the rectum

Answer 13

Mass movement

Question 14

Primary Bile Acids

Answer 14

Produced by the liver from cholesterol; primarily cholic and chenodeoxycholic acids

Question 15

Reabsorption of deconjugated bile acids

Answer 15

Passive

-Could be deconjugated by intestinal flora

Question 16

Changes in colonic fnxn w/ Constipation

Answer 16

1. Increased storage capacity of colon

2. Decreased propulsive capacity of descending and sigmoidal colon