Liver Flashcards
How many lobes does the liver have?
What are the two liver blood supplies?
2 lobes. Left (smaller) and right (bigger)
Hepatic artery and portal vein
What is/are the functional unit(s) of the liver?
Lobule or acinus
What are the components of the liver’s functional units?
Cords: rows of hepatocytes that surround central vein.
Sinusoids: blood spaces that surround the cords and drain into central vein.
Bile canaliculi: small channels between cords that carry bile to gall bladder and gut.
What are hepatocytes and what do they do?
They are the cells of the liver who respond quickly to metabolic demands and regenerate quickly.
What is the portal triad?
It is the the part of the lobule made up of the hepatic artery, portal vein and bile duct.
List the 4 functions of the liver.
Excretory: excretes bilirubin and bile.
Synthetic: synthesizes proteins, glycogen, ketones, cholesterol.
Metabolic: metabolizes drugs, ammonia, bilirubin.
Storage: stores iron, glucose, cholesterol.
What is the major substance excreted by the liver?
Bilirubin
What is bilirubin?
It is the major bile pigment formed from the breakdown of hemoglobin when RBCs are broken down in the spleen.
What type of bilirubin is released into the blood after RBCs break down in macrophages?
Unconjugated bilirubin.
What happens to unconjugated bilirubin in the bloodstream?
Since it is insoluble, it needs to be carried to the liver’s hepatocytes by albumin.
What area of the hepatocyte is unconjugated bilirubin carried to by albumin?
The endoplasmic reticulum of the hepatocyte.
Where is bilirubin conjugated and by what?
Bilirubin is conjugated in the ER of a hepatocyte by glucuronic acid.
What does conjugation make to bilirubin?
Conjugation makes bilirubin soluble and able to be excreted from the body.
What happens to conjugated bilirubin in the intestine when passed with bile?
The bilirubin is converted to urobilinogen by the normal flora of the intestine.
What is urobilinogen oxidized to?
Urobilinogen is oxidized into stercobilin which are pigments excreted in stool that gives stool its dark color, or oxidized into urobilin after it is reabsorbed into the bloodstream and excreted as urine.
What does high conjugated bilirubin in intestine do?
Increases urobilinogen.
What is the bile?
It is the greenish liquid composed of bile acids, bile salts, and bilirubin stored in the gallbladder.
What organ secrets bile acids into the bile?
The liver.
What is involved in the processing of lipids by solubilizing them?
Bile acids
Give an example of bile acid, what it is formed from and it’s function.
Cholic acid, formed from the breakdown of cholesterol and functions as the major mechanism of cholesterol elimination in the body.
Where is bile released to after a meal?
Into the small intestine.
What do aggregates of bile acids that surround dietary fat do?
They help with digestion, solubilization and absorption of lipids.
What is the liver process with bile acids?
Bile acids are recycled, reabsorbed, attached to albumin and extracted by the liver.
What synthesizes almost all proteins? And what proteins in particular?
Hepatocytes, albumin and coag factors except immunoglobulins.
List things synthesized by hepatocytes.
Glycogen Glucose Cholesterol Bile acids Ketone
What is glycogen?
It is the storage form of glucose.
How is glucose formed? And through what processes?
From the breakdown of glycogen through a process called gylcogenolysis. Or from non-carbohydrate molecules like lipids and amino acids through a process called gluconeogenisis.
When does the liver produces ketones?
When glucose is in low supply.
What does the metabolic function of the liver involves?
Detoxify and excretion.
Give examples of substances metabolized by the liver and what they are metabolized into?
Ammonia metabolized into urea.
Drugs metabolized into an inactive form, bound to protein, then excreted.
Bilirubin
Give examples of substances stored by the liver.
Irons
Glycogen
Cholesterol in the form of cholic acid
Vitamins A, D, E, K and B12
What is hepatitis?
It is an inflammation of the liver due to viral or bacterial infection or unknown causes.
Hepatitis leads to heptocellular damage.
True or false?
True
What type of hepatitis resolves in a couple of weeks and rarely cause permanent damage to the liver?
Acute hepatitis.
What type of hepatitis eventually leads to fibrosis and cirrhosis?
Chronic hepatitis.
What is fulminant hepatitis?
It is a syndrome defined as a viral liver disease that progresses in a few weeks from being symptomatic to hepatitic encephalopathy, indicating severe loss to liver function and eventually total hepatic failure.
What is the Reye’s Symdrome? And what is it followed by?
It is a rare but serious condition that causes swelling of the liver and brain. It is followed by encephalopathy.
What is the typical cause of Reye’s Syndrome?
Treating an acute viral illness like chicken pox, cold/flu in a child with Aspirin.
What are the symptoms of Reye’s Symdrome?
Vomiting, lethargy, confusion, stupor, seizures, coma.
What lab tests are made when there is suspicion of Reye’s Syndrome?
Ammonia elevation test, AST and ALT elevation test, PT and PTT elongation test,
Mitochondrial dysfunction is involved in Reye’s Syndrome. True or false?
True.
What is the estimated percentage of alcoholics that will develop cirrhosis after years of drinking?
10-15%
What does alcoholic liver damage result from?
Overconsumption of alcohol that damages the liver leading to buildup of fats, inflammation and scarring/cirrhosis.
How does alcoholic liver disease progression ranges?
Ranges from alcoholic fatty liver to hepatitis to alcoholic cirrhosis.
What are the 3 causes hepatitis in alcoholics?
- Ethanol modification of proteins in the liver.
- Acetaldehyde production from ethanol metabolism that cause direct mitochondrial damage.
- Autoimmune component.
What does alcohol produce in the body that characterizes alcoholic liver disease?
GGT Gamma-glutamyl transferase.
Steatosis—Steatohepatitis—Cirrhosis—Hepatocellulat carcinoma are trends of what disease?
Alcoholic liver disease.
What is a cirrhosis?
Cirrhosis is a progressive patterned fibrosis of the entire liver which eventually destroyes the acinus structure and obstructs portal blood flow.
What is portal blood flow?
It is blood carried by the portal vein from the gut, pancreas, spleen to the liver.
What is usually the main cause of cirrhosis?
Alcoholism
Aside alcoholism, what other things cause cirrhosis?
Chronic hepatitis, hereditary hemochromatosis.
List liver functions severely damaged by cirrhosis.
- Decreased protein levels
- Poor coagulation of blood.
- Inability of liver to metabolize toxic substances to the brain like ammonia, resulting in encephalopathy.
Healthy liver - Hepatic Steatosis - Hepatic fibrosis - Hepatic cirrhosis are stages of what?
Cirrhosis.
What is portal hypertension?
It is a very serious consequence of cirrhosis due to blockage of portal blood flow.
What part of the liver does the blood carried by the portal vein drain into?
The central vein of the lobule.
How does cirrhosis cause portal hypertension?
During cirrhosis, there is chaotic regeneration of cells (hepatocytes) and fibrosis. These block drainage of portal vein blood into the central vein.
What are symptoms of portal hypertension?
Ascites, splenomegaly, esophageal varices.
What is esophageal varices?
It is an enlargement of the lower esophagus veins due to obstructed flow through the portal vein.
What causes esophageal varices?
Portal hypertension from cirrhosis.
What is the common cause of death in cirrhotic patients?
A rupture of esophageal varices’ enlarged vein.
What is cholestatic injury?
It is a blockage of bile flow due to obstruction of biliary tree.
What is the difference between extrahepatic and intrahepatic obstruction?
Extrahepatic obstructions originate from tumor, cysts, gallstones while intrahepatic obstructions come from hepatobiliary infections, genetics, hormonal imbalance, diseases and drugs.
What will back up and leakage of bile eventually cause?
Liver cell damage and cirrhosis.
What is hepaticellular carcinoma?
This is cancer caused by chronic liver damage, that usually coexists with cirrhosis.
Most patients diagnosed with hepatocellular carcinoma die within 6 months of diagnosis. True or false?
True.
What is the most common manifestation of liver disease?
Jaundice
What are the three types of jaundice?
Pre-hepatic, hepatic and post-hepatic.
What is jaundice?
It is yellowish discoloration of the eyes, skin and mucous membranes causes by excess bilirubin due to abnormal bilirubin metabolism.
What is pre-hepatic jaundice?
It is jaundice in which issue lies in some mechanism before bilirubin reaches the liver.
What typical,y causes pre-hepatic jaundice?
Increased rate of bilirubin production/ RBC hemolysis.
What are the factors of hemolytic anemia?
Ineffective erythropoiesis
Newborn RBC
Transfusions reactions
What type of bilirubin is high during prehepatic jaundice?
Unconjugated bilirubin
What is physiological jaundice in the newborn?
It is extremely elevated UB in the newborn.
What complication can physiological jaundice if the new born bring about?
Kernicterus
What causes kernicterus from neonatal jaundice?
It is the very high levels of UB which are toxic to the brain.
What are the two factors that contribute to neonatal jaundice?
- Preemies’s RBC contain more fetal hemoglobins which generates bilirubin at a very rapid rate. (Destroyed quickly after birth)
- Liver immaturity in preemies so inability to conjugate all bilirubin produced.
What is kernicterus?
It is an irreversible brain damage caused by consistent hyperbilirubinemia.
Where does UB deposit during kernicterus?
In the basal ganglia of the brain.
How is severe jaundice treated to prevent kernicterus?
Phototherapy.
What does phototherapy involve?
Exposure to light of a specific wavelength that converts UB to a water soluble isomer so it can be digested by the intestines and kidneys.
What is hepatic jaundice?
It is jaundice in which the issue is specific or intrisic to the liver, due to helatobiliary disease which cause liver cell damage and hepatobiliary obstruction of the liver.
What bilirubin is e,elated in hepatic jaundice?
Both UB and CB
What is another name of post hepatic jaundice?
Obstructive jaundice.
What is post-hepatic jaundice?
It is jaundice caused by obstruction of extra hepatic bile ducts ducts, most commonly the common bile duct.
What type of bilirubin is elevated in post hepatic jaundice?
CB
Why is urobilinogen decreased in post hepatic jaundice?
Because conjugated bilirubin can’t reach the intestines.
What happens when no stercobilin is formed?
Stool is chalky and pale.
List the analytes that indicate hepatocellualr damage.
Elevated UB
Elevated liver enzymes AST and ALT
List the analytes that indicate cholestasis.
Elevated CB
Elevated liver enzymes ALP and GGT
List analytes indicating decreased liver function.
Decreased protein synthesis like albumin, coagulation factors.
What are the conditions for bilirubin analysis?
No hemolysis of serum or plasma
Specimen protected from light
Stable for 2h so should be tested ASAP
Why does bilirubin need to be protected from light?
Bilirubin is degraded with exposure to light.
What is total bilirubin?
Conjugated + unconjugated bilirubin
Why is UB bilirubin called indirect bilirubin?
Because it is not measured directly but found by subtracting measure total bilirubin and conjugated bilirubin.
What reagent is used during urobilinogen analysis?
Ehrlich’s reagent
Why is urobilinogen analysis done fresh?
To avoid it from oxidizing into urobilin.
How is urobilinogen analysis made?
By adding Ehrlich’s reagent to urine and sometimes stool and looking for red color. At a 460nm absorbance.
What does absence of urobilinogen indicate?
Complete biliary obstruction.
What does increased urobilinogen indicate?
Increased bilirubin in bile.
What is ammonia derived from?
Breakdown of proteins.
Ammonia is toxic to the brain true or false.
True
What does elevated ammonia indicate?
Poor liver function and one of the direct causes of hepatic encephalopathy.
What are the conditions for ammonia analysis?
Specimen cold at all times
Collection and transportation on ice slurry
Spinner in refrigerated centrifuge.
Plasma freezes within 15 mins if draw
Why does NH3 have to be kept cold at all times?
Excess NH3 can be generated from blood cell metabolism.
Lab results of acute viral, hepatitis
Hepatocellular damage
Elevated AST and ALT
Lab results for obstruction of bile ducts
Elevated CB
Elevated ALP and GGT
