Liver, Pancreas, Gallbladder Flashcards
What structures are included in the hepatic functional unit?
sinusoids, central vein, bile duct, arteriole of hepatic artery, portal venule
What is included in the portal triad?
branch of portal vein, branch of hepatic artery, bile duct
True/False: sinusoids contain only oxygenated blood from the hepatic artery
false, it contains a mixture of oxygenated and deoxygenated blood from hepatic arteriole and portal venule
What are kupffer cells? functions?
macrophages, that play an important role in innate immunity
What are stellate cells? functions?
perisinusoidal cells/pericytes that store vit A and produce extracellular matrix in response to liver damage
Briefly describe the process of lipid absorption
in the small intestinal lumen, bile salts emulsify the lipids, they are then packaged into micelles and transported across the epithelium
Describe the life cycle of bile
- bile flows out of the liver through bile ducts into the gallbladder for storage
- in response to fat, CCK is released and causes contraction of the gallbladder which releases bile into the duodenum
- bile salts do their thing with fat and then are recirculated back to the liver via portal vein
- extraction of bile salts from portal blood by hepatocytes
True/False: bile salts function throughout the length of the small intestine, from duodenum to ileum before they are recirculated back to the liver
true
What percent of bile salts end up recycled
95%
What is the purpose of bile conjugation
reduces the passive reabsorption through the lipid bilayer of cell membranes, they are more water soluble so they stay in the lumen longer
How are bile salts reabsorbed in the ileum
they are actively absorbed by Na2+ dependent secondary active transport
What are the two primary bile acids
Cholic acid
chenodeoxycholic acid
What are the two secondary bile acids
deoxycholic acid
lithocholic acid
Where are water and ions added to bile?
bile duct epithelial cells
What is the pH of bile? why?
alkaline due to the addition of HCO3- by bile duct epithelium
What are the 3 functions of the gallbladder
- store bile
- concentrate bile
- eject bile
Why do horses have no gallbladder and ruminants have gallbladder short retention time
Because they have continuous digestion and have bile flowing into the small intestine continuously
What are 7 of the essential proteins produces and released by the liver
-Glutathione
-ALB
-Clotting factors
-C reactive proteins
-Carrier proteins
- hormones and prohormones
-apolipoproteins
What are the two phases of toxin neutralization in the liver?
Phase I: conversion rxn catalyzed by enzymes (ie cytochrome P450)
Phase II: conjugation of substances
what is first pass metabolism
modification of oral drugs by the liver before entering systemic circulation
The liver is the only visceral organ with the capacity for ____
compensatory hyperplasia
What are the two functions of pancreatic secretion
-HCO3- neutralizes H+ delivered to the duodenum from the stomach
-Enzymes digest carbs, proteins, and lipids into absorbable molecules
What is the sympathetic effect on the exocrine pancreas?parasympathetic?
sympathetic inhibits pancreatic secretion
parasympathetic stimulates pancreatic secretion
Pancreatic secretion has an enzymatic part and and aqueous component, where are each secreted?
enzymes are secreted by acinar cells and the aqueous component by centroacinar and ductal cells
Which enzymes are secreted already active and which are secreted inactive?
amylase and lipase are already active while proteases are inactive
True/False: pancreatic secretion is isotonic to plasma?
true, but ionic composition can change
Which cells secrete trypsin inhibitor? why?
pancreatic gland cells, as a safeguard against proteases
Describe proenzyme activation
trypsinogen and other inactive proteases are secreted into intestine, trypsinogen is converted to trypsin by enteropeptidases, trypsin stimulates more conversation of trypsinogen as well as activates the other inactive proteases
Concentration of which ions in the aqueous component of pancreatic secretion are influenced by flow rate and which do not change
HCO3- and Cl- are influenced by flow rate
Na+ and K+ do not change
The cephalic and gastric phase of pancreatic secretion are mediated via ___
the vagal nerve
the intestinal phase of pancreatic secretion is mediated by ____
both hormonal and neural mechanisms
What phase of digestion is most pancreatic juices secreted?
intestinal
True/False: pancreatic secretion has three methods of regulation, hormonal, neural, and enteric
false, there are no enteric reflexes
What stimulates the release of CCk by the I cells of the duodenal epithelium?
nutrients in the lumen of the small intestine
Acinar cells have receptors for what molecules?
Ach and CCK
What stimulates the release of secretin by the S cells of the duodenal epithelium?
acidic contents in the lumen of the small intestine
What is the function of secretin
stimulate HCO3- rich secretion
When is secretin
