The Liver

1
The Liver

• Human Physiology Option H / Paper 3

2
Structure of the Liver

• Blood Supply
• Hepatic Artery
• Hepatic Portal Vein
• Hepatic Vein (to vena cava)

3
Structure of the Liver

• Gall Bladder
• Connects to small intestine, through duct joined
  to the pancreas, called the ampulla of Vater
• Each lobe, is made of functional units called
  acini
• Each unit is made up of hepatocytes, and kupfer
  cells, that line the sinusoids, and join to the
  central vein, along with veins, arteries and bile
  ducts

4
Acinus
5
Sinusoid
6
Bile

• Bile is a yellow, brownish or olive green liquid,
  with a pH of 7.6 8.6.
• Bile contains water, bile salts, bile pigments,
  inorganic salts and cholesterol. Bile is
  produced by the hepatocytes and travels via the
  bile canaliculi to the bile duct, which empties
  into the gall bladder. When the duct to the
  duodenum closes, the bile is pushed back and
  stored in the Gall Bladder.
•  
• Bile salts are derivatives of cholesterol and
  sodium and potassium.
• The salts have a hydrophobic side and a
  hydrophilic side This emulsifies the fat
•  
• Bicarbonate (HCO3-) in the bile, helps neutralize
  the acid of the stomach as the food enters into
  the duodenum.

7
Bile

• The principle bile pigment is bilirubin.
• The yellow, brown bilirubin is released into the
  small intestine and is broken down.
• The action of bacteria breaks it down to
  urobilinogen, which give feces its normal brown
  color.

8
Secretion of Bile

• Bile secretion is stimulated by both nervous and
  hormonal factors.
• When acid chyme come in contact with the wall of
  the duodenum, it will secrete a hormone CCK
  (cholecystokinin) causing the wall of the gall
  bladder to contract, and a relaxing of the
  spincter of the ampulla of Vater.

9
Functions of the Liver

• Carbohydrate Storage
• Storage of Iron / Breakdown of Erythrocytes
• Storage of Retinol and Calciferol
• Protein Metabolism
• Lipid Metabolism
• Detoxification

10
Damage to the Liver

• Excessive alcohol consumption can lead to
• Cirrhosis
• Fat accumulation around the liver
• Inflammation
• Jaundice
• Build up of bilirubin