78 terms

Clinical Chemistry Exam IV Prep

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The liver synthesizes
proteins, coagulation factors, ammonia, carbohydrates, fat, ketones, vitamin A, enzymes, and so on
bilirubin
principle pigment in bile that derived from hemoglobin breakdown
urobilinogen
conjugated bilirubin that has been reduced by anaerobic bacteria in the intestine
urobilin
orange-brown pigment that gives stool it's characteristic color
Jaundice (icterus)
yellow discoloration that occurs when the bilirubin/concentration in the blood rises (>2-3 mg/ dL), n and the bilirubin is deposited in the skin and sclera of the eyes
Kernicterus
elevated bilirubin deposits in brain tissue of infants, affecting the nervous system and resulting in mental retardation
The liver secretes bile to assist in
digestion
Bile salts are composed of
cholic acid and chenodeoxycholic acid conjugated with glycine and taurine
Bile is stored in the
gallbladder
The liver is the primary site in the body for
synthesis of waste products, conjugation of hormones and bilirubin to water soluble forms, and conversion of drugs to metabolites for excretion in urine or stool
The largest internal organ
liver
The liver plays a critical role in
metabolism, digestion, detoxification, elimination of substances from the body
Ability to regenerate cells destroyed by short term injury or disease
liver
The liver is extremely vascular and receives blood from 2 different sources
-hepatic artery (25%)
-portal vein (75%)
small spaces between hepatocytes that form intrahepatic ducts where excretory products of cell can drain
bile canaliculi
large cells radiating outward from central vein
hepatocytes
Kupffer cells
macrophages lining sinusoids, act as phagocytes, engulfing debris, bacteria, toxins
-microscopic units that divide the liver
-responsible for all metabolic and excretory functions
-6-sided structures with centrally located vein and portal triads
lobules
Portal triad contains
hepatic artery, portal vein, bile duct
Only organ with the capacity to rid body of heme waste
liver
made up of bile acids or salts, bile pigments, or cholesterol
bile
Body produces ____ liter(s) of bile per day
3
Body excretes _____ liter(s) of bile per day
1
principle pigment in bile derived from the break down of red blood cells
bilirubin
Amount of bile produced per day
200-300 mgs
most is eliminated in feces, some in urine
bile
Liver maintains stable glucose concentrations by storing it as glycogen and degrading glycogen when needed by the body
carbohydrate synthesis
Liver breaks down fatty acids to form triglycerides, phospholipids, or cholesterol
lipid synthesis
Liver prevents toxic or harmful substances from reaching systemic circulation by binding or chemical modification
detoxification and drug metabolism
prehepatic
problem occurs before the liver
hepatic
problem occurs within the liver
posthepatic
problem occurs after the liver
Cirrhosis is commonly caused by
alcoholism and hepatitis C
Cirrhosis
condition in which scar tissue replaces healthy liver tissue
percentage of hepatic malignancies that are metastatic, not originating in liver cells (primary)
90-95%
Benign hepatic tumors
hepatocellular adenoma, hemangiomas
Malignant hepatic tumors
hepatocellular carcinoma, hepatocarcinoma, hepatoma
Reye Syndrome
a group of disorders caused by infectious, metabolic, toxic, or drug induced disease found predominantly in children
Reye syndrome is often preceded by
viral syndrome such as varicella, gastroenteritis, or upper respiratory tract infection (influenza)
Reye syndrome has been associated with
ingestion of aspirin during viral syndrome
Acute illness in Reye syndrome is characterized by
-noninflammatory encephalopathy
-fatty degeneration of liver
-clinical presentation of diffuse vomiting
-neurologic impairment
drug induced liver disease accounts for _____ of all reported cases of acute liver failure in the us, most common mechanism of injury is adverse immune response directed against the liver
1/3 to 1/2
Most significant cause of hepatic toxicity
ethanol (alcohol)
three stages of liver disease due to excessive alcohol consumption
-alcoholic fatty liver:mild, recovery with removal of drug
-alcoholic hepatitis: evidence of liver damage
-alcoholic cirrhosis:most severe; poor prognosis
Analysis of bilirubin
based on a reaction of bilirubin with diazotized sulfanilic acid solution with a 50% methanol solution as the accelerator
three fractions of bilirubin
-conjugated (direct)
-unconjugated (indirect)
-delta
bilirubin specimen
-may be performed on serum (preferred) or plasma
-fasting sample preferred, hemolysis should be avoided
-sensitive to light and should be protected
most common methods of bilirubin analysis
Jendrassik-Grof or Malloy Evelyn
Increased levels of urobilinogen are found in
hemolytic disease and defective liver cell function
Absence of urobilinogen from urine and stool is seen with
complete biliary obstruction
quantitative methods for urobiligen involve
reaction of urobilinogen with p-dimethylaminobenzaldehyde (Erlich's reagent) to form a red color
Enzymes are released into circulation after
injury that results in cytolysis or necrosis
Enzymes can be used to differentiate ______ in liver disease
hepatocellular from obstructive liver disease
Aminotransferases of the liver
-aspartate aminotransferase ast
-alanine aminotransferase alt
Phosphatases of the liver
-alkaline phosphatase alp
-5' nucleotidase
-gamma-glutamyltransferase ggt
-lactate dehydrogenase ld
In liver disease prothrombin time pt is
commonly increased
In liver failure plasma ammonia level is
increased
serum albumin may be decreased in
decreased liver protein synthesis
hepatitis
injury to the liver characterized by inflammation in liver tissue
Causes of hepatitis
viral, bacterial, parasitic infections, radiation, drugs, chemicals, autoimmune diseases and toxins
Symptoms of hepatitis
jaundice, dark urine, fatigue, nausea, vomiting, abdominal pain
Hepatitis A (HAV)
-most common form of hepatitis world wide
-caused by infection with the virus via contaminated or improperly handled food (oral-fecal route)
Hepatitis B (HBV)
-can cause both acute and chronic hepatitis
-caused by infection with virus via parentaral, perinatal, and sexual transmission
Hepatitis C (HCV)
-caused by infection with virus via parentaral transmission (primarily blood transfusion)
Hepatitis D
-unique subvirus satellite virus infection
-requires HbsAg of HBV for replication, can only occur in pts who already have hepatitis B
Hepatitis E
-caused by infection with virus, non enveloped RNA virus that is only 27-34 nm in diameter
-transmitted primarily by fecal oral route
-characterized by water borne epidemics in developing countries
Porphyrins, hemoglobin, & myoglobin all contain
porhyrin ring: 4 pyrrole groups bonded by methene bridges
Ability to chelate metals to form functional groups that participate in oxidative metabolism
porhyrins
disorders associated with heme synthesis
porphyrias
disorders of qualitative defects in hemoglobin molecule
hemoglobinopathies
disorders of quantitative defects in production of normal hemoglobin molecules
thalassemias
Porphyrins roles in the body
-act as chemical intermediates in synthesis of hemoglobin, myoglobin, and other respiratory pigments called cytochromes
-form part of peroxidase and catalase enzymes, which contribute to the efficiency of internal respiration
-chelate iron to form heme
-used to diagnose porphyrias
porphyrins found in nature
compounds in which side chains substitute for 8 hydropgen atoms found in 4 pyrrole rings
porphyrin types I & III
-only types that occur in nature
-differ in side chain arrangement
Porphyrins are stable & red-violet to red-brown and fluouresce red when excited by light nearing
400nm
visible light
400-700 nanometers
porphyrinogens
reduced functional forms that must be used in heme synthesis, unstable, colorless, do not fluoresce
All cells contain hemoproteins and can synthesize heme, but the main sites are
bone marrow and liver