Flashcards in hepatic pathophysiology and disease Deck (69)
what are basic characteristics of the liver?
-largest internal organ
-weights about 1400-1800 g
-located right side under ribcage
-ability to regenerate
-over 500 vital functions
-involved in many digestive, vascular, and metabolic activities
what is the basic functional unit of the liver?
hepatic lobules compromised of hepatocytes
what vessels supply blood to the liver?
-portal vein (75%)
-hepatic artery (25% w/ 2/3 of O2 supply)
what percentage of CO does the liver receive?
what is unique about the hepatic portal vein?
not a true vein b/c it conducts blood to capillary beds in the liver and not directly to the heart
what is hepatic perfusion pressure (HPP)?
the combination of hepatic arterial pressure and portal venous pressure vs. hepatic venous pressure (CVP)
(HAP + HPV) - CVP
what causes decreased hepatic blood flow?
what type of receptors are found in the hepatic artery?
both alpha and beta
what receptors are found in the portal vein?
only alpha receptors
*most effected by alpha vasoconstriction, impacting liver BF
how does the liver usu. compensate for portal blood flow decrease? what blunts this response?
-hepatic artery BF increases to compensate
*halothane blunts this response
*isoflurane does NOT*
how does regional and general anesthesia affect hepatic blood supply?
both reduce hepatic blood supply to varying degrees (regional 30%)
-halothane, enflurane: decreased HPBF; may decrease or may not change HABF
-isoflurane, desflurane: decreased HPBF, increased HABF
what does the liver filter and how?
-filters blood from the GI tract
what is the amount of circulatory reservoir held by the liver to be put back into circulation when needed?
what are primary functions of the liver?
-protein synthesis (albumin, coagulation factors)
-lactate conversion into glucose
-drug metabolism and transformation
what are other functions of the liver?
-creation of bile pigments, synthesis and secretion of bile
-synthesis of cholesterol
-deposition and exchange of vit. (A, B, D), and iron, copper, zinc ions
-regulation/balance b/w coagulant and anticoagulant system; formation of heparin
-destruction of some microorganisms, bacterial ,and other toxins
-deposition of plasma in the blood; regulation of a total amt. of blood
-hemopoiesis in the fetus
what are the four primary causes of liver damage?
-inflammation: immune response
-fibrosis: scar tissue
-cirrhosis: liver cells destroyed & replaced w/ scar tissue
-hepatocellular carcinoma: liver cancer
-provides majority of oncotic pressure of the plasma
-1/2 life 14-20 days
-chief site where drugs are protein bound
-unbound portion of drugs is the portion that interacts w/ receptor sites
what happens when albumin drops below 2.5 gm/dL?
results of drugs (esp. highly protein bound) is exaggerated
what are the main morphological types of damage of the liver?
what acute and chronic diseases of the liver contribute to pathophysiology?
-infectious diseases: viruses, bacteria, spirochetes, pathogenic fungi, elementary, helminthes
-toxic substances: hepatotoxins (alcohol, drugs i.e. oncology and bone marrow suppression)
what are rare causes of hepatic dysfunction
-hyperdynamic circulation: AV malformations, hypoviscosity d/t anemia, increased intravascular volme
-hypoxemia: r-l intrapulmonary shunt, V/Q mismatch, ascites (restrictive), decreased FRC, hyperventilation w/ resp. alkalosis
what clinical manifestations are seen with hepatic dysfunction?
-increased intra abdominal pressure w/ decreased gastric emptying (ascites)
-acute renal failure
what enzymes are produced in the liver?
pseudocholinesterase and plasma esterases
*severe liver disease may cause prolonged action of succinylcholine, esmolol, and ester local anesthetics
how does hepatic extraction ratio affect drug clearance?
-drug clearance dependent on hepatic extraction ratio of the drug
-higher extraction ratio depends more on liver blood flow for clearance (propranolol, lidocaine (300%), morphine, meperidine)
-lower extraction ratio depends more on protein binding and the liver's enzymatic activity
how does decreased BF affect hepatic extraction ratio?
-affects high extraction ratio drugs
-causing to last longer
how does decreased protein (albumin) levels or protein binding issues affect hepatic extraction ratio?
-affects low extraction ration drugs
-cause to last longer
what happens with enzyme induction?
increased tolerance to some drugs from overproduction of enzymes like CP450
what are some causes of enzyme induction?
what are common drugs that show an increased tolerance d/t enzyme induction?