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57 Cards in this Set
- Front
- Back
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What are the four lobes of the liver?
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large right lobe, small left lobe, caudate and quadrate lobes
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The portal vein carries blood from what organs?
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the stomach, spleen, pancreas, small intestines, large intestine
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What are the functional units of the liver?
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the lobule
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What is the sequence of vessels that hepatic blood flows in, from the lobule back to the systemic circulation?
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branches of the portal vein » central vein » hepatic vein » inferior vena cava » systemic circulation
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What are the 2 types of cells that line the venous sinusoids of the liver?
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1. typical endothelial cells 2. Kupffer's cells (phagocytizing cells)
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Describe the movement of bile, from the lobule to the duodenum
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- bile flows into the bile canaliculi » flows into larger ducts until it reaches the right and left hepatic ducts » common hepatic duct » cystic duct joins the hepatic duct to form the common bile duct » pancreatic duct joins the common bile duct at the ampulla of Vater » through the Sphincter of Oddi into the duodenum - collectively called the hepatobiliary tree
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List the function of the liver
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- production of bile salts - elimination of bilirubin - metabolism of steroid hormones - metabolism of drugs - carbohydrate metabolism - fat metabolism - protein metabolism - storage of minerals and vitamins - filtration of blood and removal of bacteria and particulate matter
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Describe the liver's role in carbohydrate metabolism
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- stores excess glucose as glycogen - synthesizes glucose from glycerol, lactic acid, and amino acids - converts excess carbohydrates into triglycerides for storage in adipose tissue
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What are some of the important proteins that the liver produces?
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albumin, fibrinogen, and the blood clotting factors
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What are the 2 processes in the liver that are involved in amino acid interconversion?
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transamination and deamination
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What aspects of lipd metabolism occur mainly in the liver?
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- synthesis of large quanitites of cholesterol, phospholipids, and lipoproteins - formation of triglycerides from carbohydrates and proteins - formation of ketones from fatty acids
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How do statins lower cholesterol?
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- Statins are HMG-CoA reductase inhibitors - they inhibit an important enzyme in cholesterol synthesis
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What is the function of bile?
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- digestion of dietary fats - absorption of fats and fat-soluble vitamins from the intestine
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What is enterohepatic circulation?
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- the system for recirculation and recycling bile salts - reabsorbtion takes place in the distal ileum
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What is cholestasis?
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- a decrease in bile flow through the intrahepatic canaliculi and a reduced secretion of water, bilirubin, and bile acids by the hepatocytes
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Generally, what are the 2 conditions that can cause cholestasis?
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1. intrinsic liver disease (intrahepatic cholestasis) such as primary biliary cirrhosis or sclerosing cholangitis 2. obstruction of the large bile ducts (extrahepatic cholestasis) such as cholelithiasis, common duct strictures, or obstructing neoplasms
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What are some manifestations of cholestasis?
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- pruritus (severe itching) - Xanthalomas (accumulation of cholesterol under the skin) - impaired intestinal absorption - nutritional deficiencies of fat-soluble vitamins A, D, and K
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What is bilirubin?
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- formed from senescent RBCs (broken down hemoglobin) - gives bile its color
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What happens to bilirubin when it enters the liver?
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- free bilirubin (which is insoluble in plasma) is converted into conjugated bilirubin (soluble) in the liver - conjugated bilirubin is then secreted into the small intestine
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What is jaundice?
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- a yellowish discoloration of the skin due to an abnormally high accumulation of bilirubin in the blood
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What are the 4 major causes of jaundice?
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1. excessive destruction of RBCs 2. impaired uptake of bilirubin by the liver cells 3. decreased conjugation of bilirubin 4. obstruction of bile flow
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What are the 3 categories of jaundice?
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1. prehepatic - excessive hemolysis of RBCs 2. intrahepatic - disorders that directly affect the ability of the liver to remove bilirubin or to conjugate it (Hepatitis, Cirrhosis) 3. posthepatic - obstruction of bile flow (gallstones, tumors of the bile fuct
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What are some diagnostic test used to evaluate the liver?
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- AST and ALT measures liver injury - PTT (Prothrombin Time) meauses ability to synthesize proteins - Serum bilirubin, GGT and alanine phosphatase meaures hepatic excretory function
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Name and describe the 2 major types of reaction involved in the hepatic detoxification and metabolism
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1. Phase 1 - involve chemical modification or inactivation of a substance 2. Phase 2 - involve conversion of lipid-soulble substances to water-soluble substances
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What are some charcteristics of cytochrome P450?
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- a group of microsomal isoenzymes that participate in phase 1 reactions (such as oxidation, reduction, and hydroxylation
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Give an example of a phase 2 reaction
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conjugation, which makes lipid-soluble substance more water-soluble
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Give 3 examples showing the liver's role in hormone inactivation or modification
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1. insulin and glucagon are inactivated by proteolysis or deamination 2. thyroxine (T4) and triiodthyronine (T3) are metabolized by reactions involving deiodination 3. Steroid horomones (ie glucocorticoids) are inactivated by phase 1 reactions and then conjugated by phase 2 reactions
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Give 3 categories of drug-induced liver disease
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1. direct hepatotoxic injury - typically cause centrilobular necrosis 2. idiosyncratic reactions - unpredictable and not related to dose 3. cholestatic reaction - result in decreased secretion of bile or obstruction of the biliary tree 4. chronic hepatitis
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What are some causes of hepatitis?
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- autoimmune disorders - drug reactions - infectious disorders - hepatitropic viruses
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What are the 2 mechanisms of liver injury in viral hepatitis?
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1. direct cellular injury 2. induction of immune response against the viral antigens
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Which hepatotropic viruses can produce a carrier state?
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HBV, HCV, HDV (hepatitis B-associated delta virus)
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Which hepatotropic virus is a DNA virus?
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hepatitis B (HBV)
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What is the definition of chronic hepatitis?
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chorinc inflammatory reaction of the liver of more than 3 to 6 months duration
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What are some of the causes of chronic hepatitis?
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HBV, HCV, HDV, autoimmune hepatitis, and drug-induced hepatitis
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What are some characteristics of chronic viral hepatitis?
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- the principal cause of chronic liver disease, cirrhosis, and hepatocellular cancer worldwide - can be cause by HBV, HCV, HDV - most cases are due to chronic hepatitis C
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Name 3 causes of intrahepatic biliary disorders
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1. primary biliary cirrhosis 2. primary sclerosing cholangitis 3. secondary biliary cirrhosis
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What are some characteristics of pirmary biliary cirrhosis?
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- involves inflammation and scarring of small intrahepatic bile ducts, protal inflammation, and progressive scarring of liver tissue - can be caused by an autoimmune mechanism
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What are some characteristics of primary sclerosing cholangitis?
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- involves inflammation of hepatic bile ducts - a chronic cholestatic disease of unknown origin - causes destruction and fibrosis of intrahepatic and extrahepatic bile ducts - bile flow is obstructed which destroys hepatic structures
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What are some characteristics of secondary biliary cirrhosis?
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- due to prolonged obstruction of the extrabiliary tree - most common cause is cholelithiasis - other causes are malignant neoplasms of the biliary tree or head of pancreas and stricture of the common bile duct
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What are the 3 stages of alcoholic liver disease?
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1. fatty changes - reversible accumulation of fat in hepatocytes (aka steatosis) 2. alcoholic hepatitis - inflammation and necrosis of liver cells 3. alcoholic cirrhosis
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What are some characteristics of cirrhosis?
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- the end stage of chronic liver disease where functional liver tissue is replaced by fibrous tissue - manifestation can vary from asymptomatic hepatomegaly to hepatic failure
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What is portal hypertension?
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- increase resistance to flow in the portal venous system and sustained portal vein pressure above 12 mm Hg - can be caused by prehepatic, posthepatic, and intrahepatic obstruction
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What are some major complications of increased portal vein pressure?
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1. ascites 2. splenomegaly - due to shunting of blood into the splenic vein and the formation of portosystemic shunts
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What is hypersplenism?
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- a decrease in the life span and a subsequent decrease in all the formed elements of the blood - leads to anemia, leukocytosis, thrombocytosis - due to an increase rate of removal of blood elements because of the prolonged transit time through the enlarged spleen
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What are some characteristics of liver failure?
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- most severe consequence of liver disease - 80%-90% of hepatic functional capacity must be lost before liver failure occurs - manifested by disorders of synthesis, storage, metabolic, and excretory functions
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Give example of hematological disorders secondary to liver failure
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- thrombocytopenia, anemia, and leukopenia due to impaired synthesis of proteins
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What are some characteristics of hepatic encephalopathy?
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- central nervous system manifestation of liver failure - characterized by neural disturbances, such as confusion, convulsions, and coma - believed to be caused by accumulation of neurotoxins, such as ammonia
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What are the 2 major types of primary liver cancer?
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1. hepatocellular carcinoma - arises from liver cells 2. cholangiocarcinoma - a primary cancer of bile duct cells
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What is the function of the gallbladder?
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to store and concentrate bile
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What 3 factors contribute to the formation of gallstones?
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1. abnormalities in the composition of bile 2. stasis of bile 3. inflammation of the gallbladder
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What causes cholecystitis?
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- usually associated with either a complete or partial obstruction - inflammation is caused by chemical irritation from concentrated bile, mucosal swelling, and ischemia, resulting from venous congestion and lymphatic stasis
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What hormone stimulates gallbladder contraction?
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cholecystokinin
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What are the exocrine functions of the pancreas?
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- secretes digestive enzymes to breakdown dietary proteins (trypsin, chymotrypsin, carboxypolypeptidase, ribonuclease, deoxyribonuclease), starch (amylase), and fats (lipase)
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What are the names of the 2 ducts in the pancreas?
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the main pancreatic duct (or the duct of Wirsung) and the accessory pancreatic duct (or the duct of Santorini)
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Why is it important that pancreatic enzymes are secreted in their inactive form?
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- pancreatic enzymes are activated in the intestine - otherwise, pancreatic enzymes would digest the pancreas itself
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What are some characteristics of acute pancreatitis?
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- a severe, life-threatening disorder associated with the escape of activated pancreatic enzymes into the pancreas and surrounding tissues - commonly caused by gallstones or alcohol abuse
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What are the 2 tytpes of chronic pancreatitis?
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1. chronic calcifying pancreatitis 2. chronic obstructive pancreatitis
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