Liver Structure + Function Flashcards
What percentage of blood entering the liver is oxygenated and which vessel carries it?
25% through the hepatic artery
What is the portal triad?
branches of the hepatic artery, hepatic portal vein and bile duct.
What are sinusoids?
Small vessels between liver cells in lobules running into central venule, then hepatic vein.
What are bile canaliculi?
Small tubes that bile from cells flows down into the bile ducts
What is the Space of Disse?
Between the hepatocytes and the endothelial cells runs the Space of Disse. This contains stellate cells and collagen fibres
What are Kupffer cells?
Kupffer cells act as a ‘sieving system’ to prevent antigens reaching the rest of the body.
Located within sinusoidal lining – macrophages. Phagocytose bacteria, old erythrocytes, protect liver from gut derived bacteria etc.
What are pit cells?
Natural killer cells – help protect liver from viruses/tumour cells
What are hepatic stellate cells?
Lipid-filled cells. Primary site of vitamin A storage. Also control turnover of connective tissue, synthesise collagen & regulate contractility of sinusoids
Two main functions of the liver
The Factory:
carbohydrate, lipid and protein metabolism
bile formation
Waste Management:
detoxification of xenobiotics
removal of internal waste e.g.
degradation of bilirubin
What does bile contain?
water, bicarbonate, bile salts, cholesterol, phospholipids
What are either primary or secondary bile acids conjugated with?
Glycine or Taurine.
How can you increase the excretion of bile salts?
Increase fibre intake - more excretion
Cholestyramine drug - binds bile acids in the gut
prevents recirculation of bile
increases bile acid synthesis
decreases blood cholesterol
How do gallstones occur?
If more cholesterol enters the bile than can be solubilised by bile salts – precipitation of cholesterol occurs
How does acute cholecystitis happen?
When a gallstone gets stuck in the bile duct or cystic duct.
What are xenobiotics?
compounds potentially toxic, and of no nutritional value
e.g drugs or food additives
What are 3 features of phase 1 metabolism?
mainly performed by cytochrome P450 enzymes (CYP)
large family of haem proteins – mono-oxygenases
found in smooth endoplasmic reticulum
What are 3 features of phase 2 metabolism?
Conjugation – addition of glucuronyl, sulphate, methyl, acetyl, glycyl groups to reactive group on molecule
Various enzymes involved
Many of these reactions occur in liver, but also lung, kidney
What is alcohol broken down into?
Acetate, using dehydrogenases
What are RBCs mainly phagocytosed by?
Kupffer cells.
What happens to the haem molecule in haemoglobin when it is broken down?
Haem>biliverdin>bilirubin
What happens to the bilirubin?
It is transported to the liver hepatocytes attached to albumin
where it is conjugated with glucuronic acid and secreted into the bile canalicula.
In the gut it’s converted to urobilinogen.
Urobilinogen is converted into urobilin (in urine) and stercobilin (in faeces)
What is jaundice?
If there are problems with haem degradation jaundice occurs – deposition of bilirubin in tissues.
What are the 3 types of jaundice?
Prehepatic jaundice - e.g sickle cell
Intrahepatic jaundice - e.g Gilbert’s syndrome
Extrahepatic jaundice - e.g gallstones
