Special pathology - hepatic disease Flashcards
(134 cards)
The liver of domestic animals has how many lobes?
Each liver lobe is composed of ?
5-6, species dependently
Each liver lobe is composed of lobules. There are approx. 700,000 lobules in a liver.
the portal triad consists of?
hepatic artery
portal vein
bile duct
Hepatic Sinusoid
Vascular spaces, termed sinusoids, run between the hepatic plates (cords).
main exocrine function of the liver
Production and excretion of bile
Bile is composed of: (5)
-water
-cholesterol
-bile acids
-bilirubin
-inorganic ions, other constituents
purposes for bile synthesis: (3)
excretory route (for metabolic by-products)
facilitation of digestion
buffers to neutralize acids
Functions of bile acids: (3)
-maintenance of cholesterol homeostasis
-stimulation of bile flow
-intestinal absorption of fats and fat-soluble vitamins
Bile acids are synthesized in the liver from cholesterol and are conjugated with
glycine or taurine before being excreted into the bile, in order to facilitate their interaction with other components of the bile and
to prevent precipitation into calculi when they are secreted.
The quantities of bile acids required far exceed
the liver’s capacity to produce them!
Thus, using the enterohepatic circulation, bile acids are reabsorbed from the ileum,
extracted from the portal blood, and resecreted into bile.
Interruption of this process results in fat malabsorption and a deficiency of fat-soluble vitamins.
Bilirubin is produced from
the metabolic degradation of hemoglobin.
The majority of bilirubin is derived from normal extrahepatic breakdown of senescent erythrocytes with a minor contribution from degradation of tissue heme-containing proteins.
Gut bacteria deconjugate bilirubin in the GI tract and degrade it to
colorless urobilinogens.
The urobilinogens are excreted in the feces, with minimal reabsorption and excretion into urine too.
Residual urobilinogen is metabolized by bacteria into the brown pigment called
stercobilin, imparting the typical color to feces.
Name 4 plasma lipids.
cholesterol,
triglycerides,
phospholipids, and
lipoproteins
Hepatocytes can synthesize fatty acids when energy levels are high, and they can oxidize fatty acids as an energy source when necessary.
xenobiotic definition
all substances foreign to the body
e.g. drugs, toxins etc.
Cytochrome P450 enzymes of the smooth endoplasmic reticulum (microsomes) of the hepatocytes serve as the major site of metabolism of these substances in preparation for excretion in bile or urine.
what is Cytochrome P450
a major group of hepatic enzymes that play a significant role in the detoxification of xenobiotics among other tasks
Cytochrome P450 enzymes of the smooth endoplasmic reticulum (microsomes) of the hepatocytes serve as the major site of metabolism of xenobiotics in preparation
for excretion in bile or urine
endogenous substances (steroids that are lipophilic)
require conversion to ? for elimination from the body
require conversion to water-soluble forms for elimination from the body
The liver is responsible for synthesis of approximately ?% of body proteins.
The liver is responsible for synthesis of approximately 15% of body proteins.
Synthesis of the majority of plasma proteins occurs mainly within
the rough endoplasmic reticulum of hepatocytes.
Proteins produced in the liver include plasma proteins:
(7)
albumin
variety of transport proteins
lipoproteins
clotting factors II, V, and VII to XIII
plasminogen
some acute phase proteins (e.g. CRP, SAA)
components of the complement system (C1- C9)
Highly toxic ammonia is generated through catabolism of
amino acids.
Metabolic conversion of ammonia into urea, a far less toxic compound, occurs through the urea cycle, which occurs almost exclusively in the liver.
Urea then enters the systemic circulation (blood urea nitrogen) and is excreted in the urine.
The liver has a significant immune function involved in:
(3)
systemic
local
mucosal immunity
Hepatocytes participate in the response to systemic inflammation through the synthess and release of
acute phase proteins.
Approximately ?% of the cells in the liver belong to the adaptive immune system or the innate immune system.
Approximately 10% of the cells in the liver belong to the adaptive immune system (T and B lymphocytes) or the innate immune system (Kupffer cells, natural killer lymphocytes, and natural killer T lymphocytes).
Compared with other organs, the liver is particularly enriched with cells of the
innate immune system, likely a result of the fact it is the site where foreign antigens from the gastrointestinal tract first encounter the innate immune system defenses.