Form 2 Biology CD - Order Today

Structure and Function of the Liver

The liver is the second largest organ after the skin. It is both an excretory and homeostatic organ. The liver is made up of many lobules. Each lobule is made up of many liver cells. The liver receives blood from two blood vessels, the hepatic portal vein and hepatic artery. Blood drains out of the liver through the hepatic vein.

Cells of the liver

Functions of the liver


Excess amino acids are not stored in the body .They are internally broken down by the liver into urea through a series of enzyme reactions called the Ornithine cycle. During the deamination process the amino group of the amino acid is removed and converted into ammonia. The ammonia is combine with carborn iv oxide by enzymes through a series of reactions to form a less toxics compound called urea.The urea is then carried by blood to the kidney for elimination.


Toxins in the blood stream are broken down in the liver into less toxic products. For example toxic hydrogen peroxide produced in some reactions is broken down into water and oxygen by catalase enzymes in the liver. Many harmful chemicals such as alcohol and barbiturate drugs are also made less toxic to the body by the liver.

Breakdown of worn out Red Blood Cells.

Haemoglobin from worn out RBC is also broken down in the liver and the residual pigments such as urochrome is eliminated by the kidney while bilirubin is eliminated via the alimentary canal.

Besides the excretory functions above the liver has other functions such as:

  • Storage of excess sugar in form of glucose, fat soluble vitamins, Mineral salts and blood.
  • Regulation of metabolism
  • Thermoregulation
  • Red blood cell formation
  • Synthesis of plasma proteins e.g. fibrinogen
  • Blood glucose regulation

Blood glucose regulation