Lecture 10: Liver Physiology Flashcards
describe the blood flow between the liver and small intestine
- 9mmHg pressure difference
- low resistance for good blood flow
- 10% capacitance level
describe how cirrhosis affects blood flow to and in the liver
causes the liver to harden which increases resistance thus decreasing blood flow
name the metabolic functions of the liver
- carb metabolism
- fat metabolism
- protein metabolism
- detoxification
- tackling pathogens
- bile manufacture
how does the liver function as a glucose buffer
- glycogen store
- decrease blood glucose after a meal (increased glucose uptake)
- increase blood glucose between meals or during prolonged starvation (glycolysis and glucose release)
how does the liver function as a fat buffer
- right types of fats can be stored and released as and when needed
- fats stores can be used to make new glucose or make ketones + ATP
describe the relation in flow between the hepatic portal vein and hepatic artery
inversely related
which vessel in the portal area will experience more blood flow after a large meal
hepatic portal vein
which vessel in the portal area will experience more blood flow after a period of fasting
hepatic artery
what kind of pressure difference exists driving blood from artery to vein in the liver
small pressure difference therefore need low resistance to achieve big flow
describe the liver’s function in protein metabolism
- liver is principal site of synthesis of all circulating proteins except y-globulins
- amino acids from intestine and muscles undergo transamination to then make up around 90% of plasma proteins
- some amino acids undergo deamination to from ammonia; liver detoxifies ammonia to form urea which can be excreted by kidneys
describe the role of the liver in vitamin storage and activation
- liver stores vit A,D,E,K in fat stores (fat soluble vitamins)
- B12 also stored in liver (appx 80%)
- vit D activated in liver –> hydroxylated in liver then further hydroxylated in kidney
describe the detox function of the liver
- Kupffer cells present on inner wall of sinusoids –> phagocytic and remove old RBC
- haemoglobin formed into bile
- alcohol, drugs, ALP, cholesterol detoxified for excretion
- fat soluble drugs detoxified –> water soluble then removed in bile or urine
- trace metals, steroid, ammonia detoxified
describe the composition of bile
bile pigments and bile acids among other substances contained within an alkaline medium
describe the function of bile
- excretion of Hb degradation by products (pigments)
- digestion of fats (bile acids aid formation of micelles)
describe the metabolism and extraction of bilirubin
- globin part of Hb binds to bilirubin (bilirubin combines with albumin)
- this means bilirubin is not excreted in kidneys
- bound bilirubin absorbed into hepatocytes
- conjugated with glucuronic acid –> bilirubin diglucuronide (doesn’t cross into blood stream)
- then released into the bile
- broken down by bacteria in the intestine into urobilinogens
- urobilinogens can be reabsorbed into plasma (enterohepatic circulation)
