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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
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What are the liver lobules arranged around?
The Central Vein
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Which lobule has bile-producing capabilities?
All of them
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What does the portal vein do?
Transports intestinal venous blood to the liver
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What does the portal venule do?
Brings blood into lobuls from portal vein
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What are cellular plates?
- Layers of hepatocytes
- Aligned along the sinusoids
- Provide filtering, detoxification & metabolic functions
- Produce bile
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What are hepatic sinusoids?
- Endothelium-lined spaces, surrounded by cellular plates
- Receive portal (venous) blood
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What are hepatic arterioles?
- Arterial blood supply to lobule cells
- empty into sinusoids for filtration of arterial blood
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What is the Central Vein?
- Collects blood from lobule
- Empties into the hepatic vein and then the IVC
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What are Reticulo-sinusoidal cells?
- Kupffer cells
- Resident macrophages of the liver
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What are the peri-sinusoidal spaces?
- Disse Space
- Between the endothelial cell and the hepatocytes
- Area of interaction between hepatocytes and blood
- Some areas continuous with lymphatics
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What do the stellate cells do?
- Store vitamins
- Produce scar tissue
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Approximately how much blood is stored in the liver?
400-500ml
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Liver contributes almost how much lymph that is formed in the body?
1/2
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What is Cirrhosis?
- Damaged hepatocytes are replaced with fibrous CT
- Fibrous CT compresses sinusoids and reduces hepatic blood flow
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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
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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
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What can the liver synthesize in terms of fat metabolism?
- Lipoproteins
- Cholesterol
- Phospholipids
- Bile from cholesterol
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What does deamination from the liver provide?
- Convert amino acids into a form for energy release
- Provides precursor molecules for lipid synthesis
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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
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What does the liver synthesize in terms of plasma proteins
- Complement proteins
- Coagulation proteins
- Osmotic proteins
- Lipoproteins
- Synthesize all non-essential amino acids
- Interconvert various amino acids
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What vitamins can the liver store?
- Vitamin A
- Vitamin D
- Vitamin B12
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What are some of the major liver functions?
- Vitamin storage
- Iron storage
- Removal, excretion, detoxification
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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
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How/what does the liver eliminate toxic waste through feces?
- Addition of wastes to bile
- Large catabolites
- Molecules bound to plasma proteins
- Xenobiotics
- Steroid hormones
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What are some components of bile?
- Bile acids
- Phosphatidylcholine
- Cholesterol
- Electrolytes and water
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What are primary bile acids?
Bile acids that are intially synthesized by hepatocytes
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What are secondary bile acids?
Colonic bacteria that are converted into different acid molecules and and added to primary bile acid
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Primary and secondary bile acids can be conjugated with what?
- Glycine
- Taurine
- Yields ionized molecules capable of diffusing through cell membranes
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Where are most bile acids reabsorbed?
Ileum
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What are some functions of the Gall Bladder?
Storage and concentration unit for bile
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What causes the gall bladder to expel bile?
Stimulated by GB by parasympathetics and CCK to contract and expel bile
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What stimulates greater PNS outflow?
CCK
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What is Ammonia?
- NH3
- By-product of protein catabolism and bacterial metabolism
- Product of kidney function, RBC removal, mucle cell activity
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Liver converts ammonia into what?
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What unit in the liver convers ammonia to urea?
Hepatocytes
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What are some ways to asses liver function?
- Hepatocyte injury/dysfunction
- Determine dysfunction of bile excretion
- Cholangiocyte injury/dysfunction
- Response to liver therapy/transplantation
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What are some hepatocyte markers in blood serum?
- ALT - alanine aminotransferase
- AST - aspartate aminotransferase
- Bilirubin
- Serum albumin
- Prothrombin time (clotting factors)
- Ammonia/glucose
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What are some biliary system markers in blood serum?
- ALP - alkaline phosphatase
- GGT - gamma-glutamyl transpeptidase
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