Green - Bile Secretion And Large Intestine Flashcards
Substance that stimulates bile secretion
Choleretic
Reduction or stoppage of bile flow
Cholestasis
Transport of bile salts from the liver through the small intestines and blood back to the liver
Enterohepatic circulation
Bile acids synthesized by the liver from cholesterol
Primary bile acids
Primary bile acids that are modified by bacteria become?
Secondary bile acids
Relaxation of the internal anal sphincter when fecal material enters the rectum
Rectosphincteric reflex
What collects on the insides of bile salts?
Free fatty acids,
Monoglycerides
Fat-soluble vitamins
Cholesterol
What are the contents of bile?
Bile acids
Cholesterol
Phospholipids
Bile pigments
Bile’s primary excretory pathway for cholesterol is thru?
Loss of bile salts in feces
Metabolite of hemoglobin
Insoluble in water until the liver conjugates it to glucoronic acid
Leaves liver as soluble salt - glucuronide
Not in micelles
Principle bile pigment
Bilirubin
Bilirubin is secreted from the liver as ___
The soluble salt bilirubin gluconoride
Most common causes of jaundice (x2)
Increased destruction of RBC’s
Obstruction of bile duct/damage to liver cells
Predominant electrolyte composition of bile?
Na
Cl
HCO3-
A total pool of bile salts must cycle ___ times per meal
2
In the terminal ileum, where bile salts are reabsorbed for reuse, what is the transporter that does this?
Apical sodium-dependent bile salt transporter
______ bile acids can be absorbed by passive diffusion
Deconjugated
Hepatocytes extract bile salts along w/ Na from portal blood via. __________
Sodium-taurocholate cotransporting peptide (NCTP)
Defects in BSEP can cause?
Cholestasis
What is the bile-independent fraction of biliary secretion?
Volume of secretion of water and electrolytes
Bile-dependent fraction of biliary secretion is what?
Quantity of bile salts secreted by liver
Bile salts and bile acids are potent ______ of bile secretion
Stimulators
Increased secretin levels does what to the contents of the bile?
Increased bicarb
How does the gallbladder concentrate the bile?
By actively removing Na, Cl, and HCO3-
This causes water to follow the osmotic gradient
Major stimulus for gallbladder contraction?
CCK (released in response to fatty acids and small peptides in duodenum)
[vagal activity also stimulates contraction]
What are the actions of CCK on the gallbladder?
Contract smooth muscle
Relax sphincter of oddi
80% of gallstones in western societies are formed from?
Cholesterol
Pigment gallstones are composed of ?
Calcium bilirubinate
How does digestion change after cholecystectomy
Normal digestion and absorption unaffected
Bile constantly released from liver into duodenum
Fats can still be absorbed but high fat diets should be avoided
As more bile salts are recirculated to the liver, the rate of new bile acid synthesis _________
Decreases
When the ileum is distended the ileocecal sphincter ______
Relaxes
Contents flow into colon
When the colon is distended, the ileocecal sphincter _______
Contracts
Reflux into ileum prevented
______ propel material into rectum
Mass movements of the distal colon
How are suppositories able to be absorbed?
The segmentation contractions of the rectum are more frequent than that of the sigmoid colon. This means that there is retrograde material of fecal matter towards the sigmoid colon
When rectum is filled to ____ of capacity, urge to defecate is produced
25%
What happens if material enters the rectum, and the rectosphincteric reflex is triggered, but the external anal sphincter maintains its tonic contraction and defecation does not occur?
The internal anal sphincter contracts and the rectum relaxes to accomodate the fecal material w/in it and the urge to defecate subsides
Explain Hirschprung’s disease
Hirschprung’s disease, or congenital megacolon, is a disease in which there is lack of enteric nervous system for a section of colon. The enteric nervous system is inhibitory in nature, so this section is tonically contraction. This causes loss of coordinated movement and constriction, leading to build up of material proximal to the area, dilatation of the colon and severe constipation.
Increased time of passage or transit of material thru the colon
Constipation
What are the two colonic changes in function seen in constipation
Increased storage capacity of the cecum and ascending and transverse colon
Decreased propulsive capacity of the descending and sigmoid colon
What are some causes of constipation or decreased frequency of bowel movements?
Old age
Medications
Ignoring urge to defecate
Lack of exercise
Long term use of laxatives
