Lecture 35: Hepatic Physiology Flashcards
what artery provides O2 to liver
Hepatic artery
What vein transfers nutrients from GI
Hepatic portal vein
Is most liver blood venous or arterial
Venous
Blood from the liver leaves via the
Hepatic vein
What are the functional units of the liver
Lobules
What is the function of Kupffer cells
Destroy old RBC and bacteria
Vitamin A is stored as __ in __ cells
Retinol, Stellate cells
What is the space of Disse
Between hepatocytes a and sinusoids
Does blood flow towards or away from central lobule
Towards
__ and __ travel towards central lobule whereas ___ travels away
Towards: hepatic artery and portal vein
Away: bile duct
What is the outer zone (zone 1)of the hepatocyte called
Periportal
What is the inner zone (zone 3) of the hepatocyte called
Centrilobular
Which zone has high oxygen tension, many mitochondria. Is concerned with oxidative metabolism, gluconeogenesis, urea, glycogen and bile acid secretion
Zone I
Which zone has low oxygen, anaerobic metabolism, biotransformation of toxins, sensitive to ischemic necrosis
Zone III
What two capillary beds does blood run through before return to heart
Mesenteric and portal
What drives blood through portal capillary bed
Pressure in portal vein is higher than hepatic sinusoids and pre capillary resistance is low
Central vein of liver is large so decreased resistance
How does right sided heart failure cause centrilobular congestion and necrosis
Increase in vena cava pressure leads to reduced blood flow to intestines and edema. Less blood to liver, centrilobular portion is most susceptible to hypoxia
How does necrosis of hepatocytes in zone 1 (periportal) occur
- Phosphorus poisoning- rat poison, fertilizer, fireworks
- Eclampsia
How does necrosis of hepatocytes in zone 3 (centrilobular) occur
Ischemic injury, toxins
What happens to liver enzymes during necrosis of hepatocytes
Liver enzymes increase as the permeability increases and they leak out
What liver enzymes are typically elevated in necrosis of hepatocytes
- ALT
- AST
- ALP
- GGT
How does necrosis of hepatocytes effect synthetic capacity
Decreases
How does necrosis of hepatocytes effect cholesterol, glucose, glycogen, insulin, protein and coags
Decrease all
How does necrosis of hepatocytes effect conversion of ammonia to urea
Decreases uptake and conversion so increase ammonia concentration in the urine follow by PU/PD
Why does a decrease uptake and conversion to urea cause PU/PD
Concentration of urine is dependent on the tonicity of the inner medulla controlled by urea, used to osmotically absorb h20
What is the function of bile
- Excrete solutes
- Lipid digestion and absoprtion
Are are the 2 primary bile acids
Colic acid and chenodeoxycholic
The liver conjugates colic acid and chenodeoxycholic with AA taurine and glycine, what are they called
Glycocholic and taurocholic
Glycocholic and taurocholic are secreted into intestinal lumen and dehydroxylated by bacteria and produce what 2 secondary bile acids
Deoxycholic and lithocholic
How are bile salts reabsorbed in. Distal ileum and throughout intestines
Distal ileum; active transport
Intestines: passive transport
How are bile salts returned to the liver
Hepatic portal system
What is enterohepatic circulation
Bile acids secreted by liver, used for lipid digestion and absorption, reabsorbed by distal ileum and throughout intestines and returned to liver via hepatic portal system
What stimulates gallbladder contraction and relaxation of duodenal sphincter to release bile
CCK
Describe how bile acid tests work
- Fast 12hrs
- Prepranial blood draw
- Small meal and wait 2hrs
- Draw blood and test bile acids
What could possibly cause increased bile acids 2hrs after a meal
- Hepatocellular dysfunciton- can’t absorb bile acids
- Abnormal portal blood fun: shunts so don;t go through liver
- Cholestasis- interference with transporters that deliver bile
What is bilirubin
Degraded heme part of Hb in RBC
Bilirubin is bound to what in the blood
Albumin
Bilirubin is extracted from blood by hepatocytes and conjugated with
Glucuronic acid
Bilirubin glucoronide is secreted into bile and then turned into ___
Bilirubin and urobilirubin
What determines color of feces
Oxidized urobilin and stercobolin
What form of bilirubin is in the blood
Unconjugated bilirubin bound to albumin
What kind of bilirubin is in hepatocyte
Conjugated bilirubin (glucuronic acid)
What kind of bilirubin is in the SI—> terminal ileum—> colon
SI: conjugated
ileum: urobilinogen
Colon: urobilin and stercobilin
What can cause increased bilirubin
- Excessive production via increased RBC destruction (hemolytic anemia)
- Insufficient removal- block bile ducts
If bilirubin does not pass through the liver or passes too quickly through what form of bilirubin is present: conjugated or unconjugated
Unconjugated
If something prevents the secretion of bilirubin into bile what form of bilirubin is present: conjugated or unconjugated
Conjugated
Jaundice is a result of bilirubin production ___bilirubin excretion
Exceeding
What causes pre-hepatic/hemolytic jaundice
Breakdown of RBC—> liver gets more bilirubin than it can handle
What causes hepatic jaundice
Liver disease unable to deal with normal amounts of bilirubin
What causes post hepatic/obstructive jaundice
Bile duct is blocked (gallstone) bilirubin not excreted
What are Chloelithiasis
Stones in bile duct or gallbladder
How do cholethiasis affect feces color
Decrease urobilin and stercobilin secretion—> lighter or grey
What is the treatment for cholethiasis
Low fat/high protein diet, sx
What type of hyperbilirubin is a result of cholethiasis: conjugated or unconjguated
Conjugated
What causes neonatal isoerythrolysis/jaundice foal
Mare creates antibodies to foals RBC which are secreted in RBC and results in hemolytic anemia—> increased bilirubin to liver, more than it can excrete
What type of hyperbilirubin is neonatal isoerythrolysis/ jaundice foal
Unconjugated
How can you test for neonatal isoerythrolysis/ jaundice foal
Milk and foal blood agglutination test
