Hepatic Physiology Flashcards
what is the heaviest gland in the body and how large is it in the avergae adult?
liver; about 3lbs
where is the liver located?
inferior to the diaphragm
what are the two sections of the liver? what divides them?
right and left lobes; divided by the falciform ligament
what is the falciform ligament?
a fold of mesentery that divides the right and left lobes of the liver
what is the gallbladder? where is it located? what is its function?
a pear shaped sac located in the depression of posterior surface of the liver that stores bile
what are 13 functions of the liver?
- filtration and storage of blood
- metabolism of carbohydrates, proteins, and fats
- detoxification/degradation of body wastes, hormones, drugs, and foreign compounds
- plasma protein synthesis
- storage of glycogen, fats, iron, copper, and many vitamins
- activation of vitamin D
- removal of bacteria and worn-out red blood cells
- excretion of cholesterol and bilirubin
- synthesis of ascorbic acid (vitamin C)
- bouyancy in sharks
- gluconeogenesis
- lipogenesis for yolk
- formation of bile
what is the basic functional unit of the liver? (the less preferred way to view it)
the liver lobule
what is a liver lobule?
hexagonal arrangement of tissue surrounding a central vein
what 3 vessels are on the outer edge of the liver lobule? what do these three vessels form?
- branch of hepatic artery
- branch of portal vein
- bile duct
THE HEPATIC TRIAD
what do the central veins of all liver cells converge to form?
the hepatic vein
what is the function of the hepatic vein?
carries blood away from the liver
what are the two sources from which the lvier receives blood?
- arterial blood
- venous blood
describe blood flow between the liver, the GI tract, and the heart (4)
- the liver receives blood from arterial blood and venous blood
- arterial blood provides the liver’s O2 supply and carries blood-borne metabolites for hepatic processing and is delivered by the hepatic artery
- venous blood draining the GI tract is carried by the hepatic portal vein to the liver for processing and storage of newly absorbed nutrients
- blood leaves the liver via the hepatic vein
how does blood get to the liver?
the hepatic artery and portal vein drain into sinusoid capillaries, which drain into the central vein, which will drain into the hepatic vein
what do hepatocytes do in the liver lobule?
continuously secrete bile into bile canaliculis
what do bile canaliculis do in the liver lobule?
carry bile to the bile duct
what do bile ducts from various liver lobules converge to form? what is its function?
the hepatic duct, which transports bile from the liver to the duodenum
what is the preferred view of the structural and functional unit of the liver? describe
the hepatic acinus, which is an oval mass thta includes portions of 2 neighboring hepatic lobules
how is the hepatic acinus divided?
into 3 zones
describe the cells of zone 1 of the haptic acinus (4)
- cells are closest to branches of the hepatic portal triad
- these cells are the first to receive incoming O2, nutrients, and toxins
- these cells are the first to show morphological changes following bile duct obstruction of toxin exposure
- these cells are the last to die if circulation is impaired
describe the cells in zone 3 of the hepatic acinus
- these cells are farthest from the branches of the protal triad
- these cells are the last to show effects of bile obstruction or toxin exposure
- these cells are the first to show effects of impaired circulation
- these cells are the last to regenerate
describe the blood flow and vascular resistance of the liver
the liver has high blood flow and low vascular resistance
what percent of resting cardiac output does the liver receive? why?
27% because it is responsible for so many metabolic processes
what 2 conditions caused increased vascular resistance in the liver?
- liver cirrhosis
- portal hypertension
what is cirrhosis of the liver?
destroyed liver parenchymal cells are replaced with fibrous tissues which contracts around the blood vessels
what are 3 causes of liver cirrhosis? what links these causes together?
- alcoholism
- poisoning
- viral diseases
all cause release of proinflammatory cytokines