Lecture 46 11/30/23 Flashcards
What are the characteristics of the hepatic lobule?
-anatomic unit of the liver
-consists of portal triad, linear cords of hepatocytes, and central vein
What are the functions of the liver?
-filtration and storage of blood
-metabolism of carbs, fats, proteins, hormones, bilirubin, and foreign materials
-formation and excretion of bile
-reabsorption of bile acids
-storage of vitamins and iron
-formulation of plasma proteins and coagulation factors
How does the liver receive blood?
-hepatic artery
-portal vein
What are the characteristics of Kupffer cells?
-specialized macrophages
-part of mononuclear phagocyte system
-terminate bacteria that enters liver through portal blood
-responsible for metabolism of old RBCs
Why is it important that the liver is an expandable organ?
-stores excess blood when the right atrium of the heart is not functioning properly
-releases additional blood during times of acute blood loss
Why does the liver have high lymph flow?
-pores in hepatic sinusoids are very permeable
-permeability allows for passage of fluid and proteins and contribution of a large volume of lymph
What are the functions of the liver in carbohydrate metabolism?
-storage of glycogen
-gluconeogenesis
-conversion of galactose to glucose
-fructose metabolism
-formulation of intermediate products required for glucose metabolism
What are the functions of the liver in fat metabolism?
-oxidation of fatty acids
-cholesterol, phospholipid, and lipoprotein synthesis
-synthesis of fat from protein/carbs
What are the functions of the liver in protein metabolism?
-deamination of amino acids
-formation of urea for ammonia removal
-formation of plasma proteins
-interconversion of amino acids
-synthesis of other compounds from amino acids
What are the characteristics of albumin?
-important plasma protein
-accounts for 50% of the substances synthesized by the liver
-contributes 80% to plasma oncotic pressure
What are the functions of the liver in foreign material/hormone metabolism?
-removes excess drugs, hormones, and other substances
-excretes or alters hormones from endocrine glands
-hepatocytes express large numbers of enzymes to convert drugs, toxins, and other materials into metabolites
Which vitamins and minerals are stored in the liver?
-vitamin A/retinol
-vitamin D/calciferol
-vitamin B12/cobalamin
-iron stored as ferritin
What are the functions of the liver in coagulation factor production?
-produces almost all clotting factors
-produces many clotting inhibitory proteins
Why is it important that the liver can slow/stall bile flow through the biliary system?
can result in decreased intestinal vitamin K absorption, leading to a vitamin K deficiency and potential problems with clotting
What is bilirubin?
a product of heme metabolism
What is heme?
an iron-containing compound
What are the characteristics of hemoglobin?
-contains 4 heme groups
-protein in RBCs
-allows for oxygen transport
What are the characteristics of myoglobin?
-contains 1 heme group
-protein in striated muscles
-serves as intracellular storage site for oxygen
Which type of conditions can increase bilirubin formation?
conditions that increase the turnover rate of RBCs
Why is it important that bilirubin has an orange-yellow color?
leads to the yellow appearance of icterus
Which enzymes are involved in the generation of bilirubin?
-heme oxygenase
-biliverdin reductase
What is the role of heme oxygenase?
convert heme into biliverdin, which is green
What is the role of biliverdin reductase?
convert biliverdin into bilirubin
What are the characteristics of bilirubin solubility and conjugation?
-unconjugated bilirubin is not water soluble, and circulates in the blood bound to albumin
-unconjugated bilirubin is transported to the liver
-liver removes bilirubin from plasma and conjugates bilirubin to glucuronic acid
-conjugated bilirubin is secreted in bile
What are the characteristics of bilirubin in the intestines?
-bacteria remove glucuronic acid to form urobilinogen
-urobilinogen can be oxidized to urobilin, giving urine the yellow color
-urobilinogen in intestines is oxidized to stercobilin to give feces brown color
What is the pre-hepatic cause of high blood bilirubin?
increased production due to RBC lysis
What is the hepatic cause of high blood bilirubin?
inadequate uptake, conjugation, and/or biliary excretion
What is the post-hepatic cause of high blood bilirubin?
abnormal biliary excretion of bilirubin
What are the characteristics of bile component recycling?
-bile components move from the liver to the small intestine, portal vein, and back to the liver
-bile, bilirubin, toxins, and drugs can circulate between the liver and intestines
What are the characteristics of hepatic regeneration?
-liver is able to restore functional tissue following injury or lobe removal
-infectious or inflammatory conditions may complicate recovery
-regenerative ability not completely understood
