Liver Function Flashcards
Blood vessel that conducts blood from the gastrointestinal tract and spleen to the liver
Function of the portal vein
A branch of the celiac artery that supplies oxygenated blood to the liver
Function of the hepatic artery
Low pressure vascular channels that receive blood from terminal branches of the hepatic artery and portal vein at the periphery of lobules and deliver it into central veins
Function of sinusoids
Its primary function is to collect and transport the bile produced by hepatocytes, or liver cells
Functions of the bile canaliculi
In a patient w/ liver disease, will GLUCOSE increase or decrease?
DECREASE
In a patient w/ liver disease, will ACUTE PHASE REACTANTS increase or decrease?
INCREASE
In a patient w/ liver disease, will ALBUMIN increase or decrease?
DECREASE
In a patient w/ liver disease, will TRANSTHYRETIN increase or decrease?
DECREASE
In a patient w/ liver disease, will IMMUNOGLOBULINS increase or decrease?
DECREASE (abnormal)
In a patient w/ liver disease, will COAGULATION PROTEINS increase or decrease?
DECREASE
In a patient w/ liver disease, will AMMONIA increase or decrease?
INCREASE
In a patient w/ liver disease, will UREA increase or decrease?
DECREASE
In a patient w/ liver disease, will CHOLESTEROL increase or decrease?
DECREASE
In a patient w/ liver disease, will LIPOPROTEINS increase or decrease?
DECREASE
Two hepatic mechanisms for detoxification and excretion of xenobiotic materials and toxic metabolic products
- Excreted directly into the bile for fecal excretion
- Circulated to the kidney for renal excretion
Three functions of Kupffer cells
- Store iron (vitamins A, E, K and other substances)
- Phagocytic action
- Immune mechanism
Most potent Ag-presenting cells of the immune system and also serve to characterize the pathogenicity of invading Ags
Function of dendritic cells
They store vitamin A in a normal liver, limit fibrosis upon senescence, and secrete collagen upon liver damage
General functions of stellate cells
A patient w/ liver disease will have altered drug concentrations and ability to absorb and store vitamins…Why?
?
Metabolic degradation of hemoglobin including the final deposition of iron, heme, and globin
- Senescence of RBCs are picked up by the spleen, liver and bone marrow.
- RES breaks the RBCs down into heme and and globinand iron; heme goes on to bilirubin; globin returned to amino acid pool; and iron returns to the iron stores
- Bilirubin leaves the RES as unconjugated bilirubin (toxic) and is taken up by the liver
Metabolic conversion of heme to unconjugated bilirubin, then conjugated to bilirubin
- The hepatocyte conjugates the bilirubin by adding one or two glucuronide molecules via catalysis by UDP-Glucuronyl transferase and it enters the small intestine through the common bile duct
- Conjugated bilirubin has 3 fates
1. 50% absorbed into plasma; of that 50%, 30% goes back to liver and 20% is filtered by the kidney as urinary urobilinogen then excreted as urobilin
2. 50% is not reabsorbed and excreted as fecal urobilinogen —> urobilin
Transport protein for unconjugated bilirubin
Albumin
Formation of bilirubin mono- or diglucuronide (conjugated bilirubin), including the name of the enzyme that catalyzes the reaction
- Conjugated bilirubin is formed by conjugation w/ one or two glucuronide molecules via catalysis by UDP-glucuronyl transferase
Structure in the hepatocyte into which conjugated bilirubin is secreted
Once conjugated, it’s secreted into the common bile duct (bile canaliculus) on to the small intestine
Formation, reabsorption, and urine/fecal excretion of urobilinogen
- Once in the intestine, conjugated bilirubin is transformed to urobilinogen
- 50% is excreted as fecal urobilinogen
- Other 50% is reabsorbed into the plasma (3% back to the liver, 20% is excreted as urinary urobilinogen)
Pre-hepatic jaundice
- General cause
Any process that cuases premature RBC destruction and increased production of unconjugated bilirubin
Pre-hepatic jaundice
- 4 specific causes
- Hemolysis
- Ineffective erythropoiesis
- Increased turnover of non-hemoglobin heme compounds
- Hematoma
Pre-hepatic jaundice
- Serum total bilirubin
- Unconjugated bilirubin
- Conjugated bilirubin
- Urine bilirubin
- Urine urobilinogen
- Fecal urobilinogen
- Serum total bilirubin: increased
- Unconjugated bilirubin: increased
- Conjugated bilirubin: normal
- Urine bilirubin: negative/normal
- Urine urobilinogen: increased
- Fecal urobilinogen: increased
Post-hepatic jaundice
- General cause
Caused by any process that prevents excretion of conjugated bilirubin (biliary obstructive disease)
Post-hepatic jaundice
- Three specific causes
- Ductal occlusion by stones
- Spasms or strictures
- Compression by neoplastic diseases (tumors)
Post-hepatic jaundice
- Serum total bilirubin
- Unconjugated bilirubin
- Conjugated bilirubin
- Urine bilirubin
- Urine urobilinogen
- Fecal urobilinogen
- Serum total bilirubin: increased
- Unconjugated bilirubin: normal
- Conjugated bilirubin: increased
- Urine bilirubin: positive
- Urine urobilinogen: decreased to absent
- Fecal urobilinogen: decreased to absent
Post-hepatic jaundice
- Four enzymes that are elevated to a significant degree
- ALP
- GGT
- LAP
- 5’NT
In hepatic (hepatocellular) jaundice, the hepatocyte itself is “sick”; which functions are impaired?
- Impaired uptake
- Impaired conjugation
- Impaired excretion
Hepatocellular disease
- Causes
- All 3 processes (uptake, conjugation, and excretion of bilirubin) are impaired
- Most common cause is HEPATITIS
Hepatocellular disease
- Expected serum total
- Unconjugated bilirubin level
- Conjugated bilirubin level
- Urine bilirubin level
- Fecal and urine urobilinogen levels
- Elevated enzymes in hepatitis
- Serum total bilirubin: increased
- Unconjugated bilirubin: increased
- Conjugated bilirubin: increased
- Positive
- Normal to decreased
- Elevated enzymes: ALT > AST, ALP, LD4/LD5, NH4+ (can’t be detoxified to urea, so BUN will be low!)
Gilbert’s disease
- Causes
Pre-conjugation transport failure
Gilbert’s disease
- Mechanism
- Normal amt of unconjugated bilirubin to the “sick” liver
- Impaired uptake of unconjugated bilirubin
- Decreased conjugated bilirubin to gut
Gilbert’s disease
- Serum total
- Unconjugated level
- Conjugated level
- Urine bilirubin
- Urine and fecal urobilinogen
- Serum total: increased
- Unconjugated: increased
- Conjugated: decreased
- Urine bilirubin: negative
- Urine and fecal urobilinogen: decreased (normal)
Crigler-Najjar Syndrome
- Causes
Conjugation failure
Crigler-Najjar Syndrome
- Mechanism
- Normal amt of unconjugated bilirubin to “sick” liver
- No conjugation occurs → unconjugated bilirubin leaks back into blood
Crigler-Najjar Syndrome
- Serum total
- Unconjugated level
- Conjugated level
- Urine bilirubin
- Urine and fecal urobilinogen
- Serum total: increased
- Unconjugated: increased
- Conjugated: decreased
- Urine bilirubin: negative
- Urine and fecal urobilinogen: decreased
Physiologic jaundice of the newborn
- Causes
Conjugation failure (common/normal), liver not yet producing UDP-glucuronyl transferase yet b/c immature
Physiologic jaundice of the newborn
- Mechanism
- Normal amt of unconjugated bilirubin to immature liver
- No conjugated bilirubin to gut b/c liver isn’t producing UDP-glucuronyl transferase yet
- Unconjugated bilirubin leaks into blood