Histo Lecture 18
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Histo Lecture 18
What are some functions of the liver?
Flitration of blood
Metabolism of proteins, fats, carbohydrats
Formation of bile
Storage of vitamins and iron
Formation of coagulation factors, plasma proteins
Detoxification of metabolites and exgenous compounds
What are the liver lobules arranged around?
The Central Vein
Which lobule has bile-producing capabilities?
All of them
What does the portal vein do?
Transports intestinal venous blood to the liver
What does the portal venule do?
Brings blood into lobuls from portal vein
What are cellular plates?
Layers of hepatocytes
Aligned along the sinusoids
Provide filtering, detoxification & metabolic functions
What are hepatic sinusoids?
Endothelium-lined spaces, surrounded by cellular plates
Receive portal (venous) blood
What are hepatic arterioles?
Arterial blood supply to lobule cells
empty into sinusoids for filtration of arterial blood
What is the Central Vein?
Collects blood from lobule
Empties into the hepatic vein and then the IVC
What are Reticulo-sinusoidal cells?
Resident macrophages of the liver
What are the peri-sinusoidal spaces?
Between the endothelial cell and the hepatocytes
Area of interaction between hepatocytes and blood
Some areas continuous with lymphatics
What do the stellate cells do?
Produce scar tissue
Approximately how much blood is stored in the liver?
Liver contributes almost how much lymph that is formed in the body?
What is Cirrhosis?
Damaged hepatocytes are replaced with fibrous CT
Fibrous CT compresses sinusoids and reduces hepatic blood flow
What is Portal Hypertension?
Increased venous pressure in the liver
Increased pressure promotes fluid transudation from sinusoids to the lymph and the surface of the liver
-Results in ascites (fluid build-up in the abdomen)
Can also cause esophageal varices, caput medusa, internal anal hemorrhoids
How does the liver control blood glucose?
Stores excess glucose as glycogen; releases it as needed (glucagon)
Produce glucose from amino acids and glycerol (gluconeogenesis)
converts disaccharides into glucose
What can the liver synthesize in terms of fat metabolism?
Bile from cholesterol
What does deamination from the liver provide?
Convert amino acids into a form for energy release
Provides precursor molecules for lipid synthesis
How does the liver play a role in urea formation?
Ammonia is formed during deamination by bacteria within the GI tract
Liver converts it to urea for renal excretion
What does the liver synthesize in terms of plasma proteins
Synthesize all non-essential amino acids
Interconvert various amino acids
What vitamins can the liver store?
What are some of the major liver functions?
Removal, excretion, detoxification
What are some methods of liver detoxification?
Limits release of substances into circulation
Extracts toxic substances and converts them for excretion
-Altered to water soluble products that can be easily excreted
Conversion and conjugation to other molecules
How/what does the liver eliminate toxic waste through feces?
Addition of wastes to bile
Molecules bound to plasma proteins
What are some components of bile?
Electrolytes and water
What are primary bile acids?
Bile acids that are intially synthesized by hepatocytes
What are secondary bile acids?
Colonic bacteria that are converted into different acid molecules and and added to primary bile acid
Primary and secondary bile acids can be conjugated with what?
Yields ionized molecules capable of diffusing through cell membranes
Where are most bile acids reabsorbed?
What are some functions of the Gall Bladder?
Storage and concentration unit for bile
What causes the gall bladder to expel bile?
Stimulated by GB by parasympathetics and CCK to contract and expel bile
What stimulates greater PNS outflow?
What is Ammonia?
By-product of protein catabolism and bacterial metabolism
Product of kidney function, RBC removal, mucle cell activity
Liver converts ammonia into what?
What unit in the liver convers ammonia to urea?
What are some ways to asses liver function?
Determine dysfunction of bile excretion
Response to liver therapy/transplantation
What are some hepatocyte markers in blood serum?
ALT - alanine aminotransferase
AST - aspartate aminotransferase
Prothrombin time (clotting factors)
What are some biliary system markers in blood serum?
ALP - alkaline phosphatase
GGT - gamma-glutamyl transpeptidase