Flashcards in Hepatobility Deck (51):
What is the functional unit of the liver?
What is a lobule structure?
-Hexagonal shape, triad of bile duct/hepatic portal vein/hepatic artery at each corner.
-Lobule is all hepatocytes which drain into one central vein.
-Make up ~80% of liver volume
What is the function of microvilli on each side of liver endothelium?
-Increase surface area
What are Kuppfer cells?
-Macrophages in sinusoid which consume RBCs, bacteria
What is the function of endothelial cells in the liver?
-Line the sinusoids, make it very porous so large particles and proteins and shit can move through.
What are the stellate cells in the liver?
-Fat storing cells for vitamin A and fat soluble vitamins
-Can turn into myofibroblasts in the case of liver damage. May play a role in cirrhosis.
What are cannaliculi in the liver and what flows through them?
-Channels between cell membranes of adjacent hepatocytes which carry bile
Describe preferential enzyme expression:
-Function of hepatocytes is determined by their relative proximity to central veins.
-Zone 1 is furthest from central vein, thus most highly oxygenated
-Zone 3 is closest to central vein and least oxygenated
What do Zone 1 hepatocytes carry out?
-amino acid metabolism, gluconeogenesis, ureageneis, cholesterol synthesis, and bile formation
What do zone 3 hepatocytes carry out?
How much of the liver oxygen supply comes from the portal vein? Hepatic artery?
What are the functions of the liver?
-Hormone conversion and activation
What is phase 1 of biotransformation?
-Oxidation-reduction, cytochrome P450 enzyme
What is phase 2 of biotransformation?
-Conjugation to make metabolites more polar/water soluble for excretion
What carries out filtration at the liver?
How are hormones converted and activated at the liver?
-Vitamin D is hydrolyzed here
-T4 is deiodinized into T3
What is the main nutrient metabolized at the liver? How?
-Converts CHO to triglycerides for storage as fat outside of liver
What are the three forms of cholesterol?
-Dietary (as chylomicrons)
What are the two ways that cholesterol is exported from the liver?
-As bile acids
-As VLDL to be sent to other cells to make cellular components or steroid hormones
What proteins are produced at the liver?
What is the main function of albumin?
-Maintains plasma oncotic pressure.
-Binds and transports substances in blood.
How are proteins metabolized?
What is transamination?
-Transfer of an amino group to a ketoacid to participate in gluconeogenesis, lipid synthesis
What is bilirubin? What is it's function?
-Pigment that occurs when RBCs break down.
-Gives bile it's color
How is bilirubin formed?
-RBC breaks down, biliverdin is formed
-converts to free bilirubin, binds to albumin in blood
-converts to conjugated bilirubin in blood, now conjugated.
What is jaundice and how is it caused?
Yellowing of the skin. Due to excessive biulirubinas a result of excess bilirubin lysis, decreased hepatic blood flow, obstruction of bile ducts, reduced conjugation of bilirubin.
What is the function of bile?
-Allows bilirubin and cholesterol to be excreted
Wha do bile acids and bile salts promote?
Digestion and absorption of lipids.
What are micelles? What do they do?
Formed by bile salts and bile acids. They emulsify lipids so they can be absorbed
Why is gallbladder bile more concentrated than hepatic bile?
-Water is taken out;
Describe enterohepatic circulation
-More bile is excreted than is generated, most of this is reabsorbed.
What are ALT and AST?
-tells you about liver damage
What does serum albumin tell us?
-About synthetic capability of l;over
-If the liver can make proteins
What does alkaline phosphatase tell us?
-about liver excretory function.
What is the function of the gallbladder?
Secrete concentrated bile into duodenum
What is cholestasis? Causes?
-blockage of gallbladder
-Stones, cirrhosis, neoplasm outside of liver
-Common symptom is itching
What is cholestisis? Acute vs Chronic? Signs
-Inflammation of gallbladder
-Associated with partial or complete obstruction of cystic or common duct.
-Acute signs=vomiting, right upper quadrant pain
-Chronic: pain, intolerance to fatty foods
What is cholelithiasis? Cause?
-Too much cholesterol, not enough bile salts
What is hepatitis?
-Viral infection of liver cells
-Most cellular damage comes from self immune response
Describe Hep A
-No symptoms in kids, jaundice in adults
-DNA, blood borne and bodily fluids
-There is a vaccine
-Can cause cirrhosis and necrosis
-plays role in Hep D
-RNA virus, blood borne
-Most commonly vaccinated for
-Can be acute or chronic
-May cause cancer
-Requires Hep B infection
-No treatment, DNA virus, blood borne.
-Can be acute or chronic
-RNA virus, fecal oral transmission
-Similar to Hep A
-Impacts pregnant women
Basically Hep C
Describe chronic hepatitis
-Result of B, C, or D
-Most common cause of liver transplant in adults
What is pancreatitis?
-Inflammation of pancreas due to alcohol or trauma
-Enzymes from pancreas released to surrounding tissues
-Chronic due to alcohol abuse or cystic fibrosis
How is pancreatitis treated?
-Total Parenteral Nutrition
Describe liver cancer
-Highly linked to Hep B and Hep C
-Low survival rate
-Associated with cirrhosis
Describe pancreatic/gallbladder cancer
-Prancreatic is 4th most common cause of cancer death
-common in blacks
Gallbladder cancer: 1% 5 year survival rate, diagnosed at surgery because symptoms involve gallstones