6: Jaundice & The Liver Flashcards
what separates the left and right lobes of the liver
the falciform ligament
lobes divided into
segments (8 in total)
segments comprise of
Hepatic Lobules
what’s the functional unit of the liver
Hepatic Lobules
describe Hepatic Lobule
Hexagonal arrangement Around a CENTRAL VEIN At each 6 corners: -a branch of the HEPATIC ARTERY -a branch of the HEPATIC PORTAL VEIN -a BILE DUCT
blood flows from hep artery and hep portal vein via…
sinusoids
sinusoids lined by
Kupffer cells - engulf old RBCs and bacteria from the blood
cells of the liver
80% Hepatocytes.
10% Sinusoidal endothelial cells
9% Immune Cells
1% Bile Duct Endothelial Cells
name for spaces between hepatocytes, cells found there and what they store
a. Spaces of Disse
b. Stellate cells
c. Store Vitamin A
Blood Supply
75% - Hepatic Portal Vein -formed by veins draining the GIT -these contain all the absorbed nutrients 25% - Hepatic Artery -arises directly off the Aorta Blood then LEAVES Liver via Hepatic VEIN
what does the Hepatic Artery provide to the liver
- metabolites
2. oxygen supply
what vein converge to form the Hepatic Vein (leaving liver)
The Central Veins
where does the Hepatic Vein flow
Inferior Vena Cava
what is the driving force of bile flow
Osmotic gradient of bile salts and sodium created by hepatocytes
describe the pathway of bile
hepatocytes –> bile canaliculi –> INTRAhepatic Bile Ducts –> Left/Right Hepatic Duct –> Common Hepatic Duct –> Common BILE Duct (formed also by CYSTIC DUCT from gallbladder joining it)
Sphincter of Odi
maintains the pressure within Common BILE Duct by rhythmic contraction and relaxation
how is gallbladder bile
10x more concn due to reabsorption of water and electrolytes
role of gallbladder contraction
force out bile into duodenum by applying pressure to the Common Bile Duct
Functions of Liver (first 3)
- Metabolism of carbs, amino acids and lipids after their absorption
- Detoxification and degradation of:
- body wastes
- hormones
- drugs - Synthesis of Plasma Proteins
- needed for Blood Clotting
- Angiotensinogen (important in RAAS)
- Transport of Cholesterol, Thyroid Hormones and Steroids
Functions of Liver (next 3)
4.Storage of Glycogen, Fats, Iron, Copper, Large amounts Vit A, D & B12
5.Removal of BACTERIA
-old RBCs
due to its resident macrophages
6.Activation of Vit D (7-dehydrocholesterol) to 25-OH Vitamin D. Activation is done in conjunction w kidneys
Functions of Liver (last 3)
- Secreting Hormones
- Secreting Acute Phase Proteins
- Excreting Cholesterol and Bilirubin
List hormones secreted
- THROMBOPOIETIN - stimulates platelet production
- Insulin-like Growth Factor I (stimulates growth)
- HEPCIDIN - stimulates iron uptake from the intestine
Coagulation factors produced
1. Clotting Factors: II VII IX X 2.Proteins involved in Clotting Cascade *synthesis of these impaired when deficiency of Vit K as these are post-translationally modified by Vit K-dependent ENZYMES
Role of plasma protein Albumin
- transport of Bilirubin
2. transport of hormones throughout body & drugs
Bilirubin a product of
Heme catabolism
Bilirubin form in the blood
Unconjugated - bound to albumin.
This form is taken up by hepatocytes at the sinusoidal mebrane & conjugated
Fate of conjugated bilirubin
exported into Bile Canaliculus by Specific Carriers and excreted in Bile into the bowel lumen
name of product to which colonic bacteria metabolize bilirubin & fate
StercoBILINOgen which may be further oxidised into STERCObilin
both are excreted in faeces (gives dark colour)
