Important Functions of Liver | Human Physiology

The following points highlight the nineteen important functions of liver. Some of the functions are: 1. Production of Bile 2. Deamination 3. Excretion 4. Glycogenesis 5. Glycogenolysis 6. Lipogenesis 7. Gluconeogenesis 8. Detoxification 9. Haemopoiesis 10. Synthesis is Blood Proteins 11. Secretion of Heparin 12. Lymph Formation 13. Synthesis of Vitamin A 14. Secretion of Enzymes and Others. 

Function # 1. Production of Bile:

The liver secretes bile (hepatic bile pH 8.6). The bile is stored in the gall bladder (gall bladder bile pU. 7.6). About 500 – 1,000 ml of bile is secreted by liver in a day.

Bile salts (sodium bicarbonate, sodium glycocholate, sodium taurocholate) help in the digestion of fats in the small intestine by bringing about their emulsification (conver­sion of large fat droplets into small ones). Usual flow of bile from the liver is → hepatic ducts gall bladder → cystic duct → bile duct → hepatopancreatic ampulla → duodenum.

Function # 2. Deamination:

It is a process by which the amino group (—NH₂) is removed from the amino acids resulting in the production of ammonia which is converted into urea.

Function # 3. Excretion:

(i) Liver synthesizes urea with the help of ammonia and carbon dioxide. Urea is passed out through excretory system,

(ii) The bile contains bile pigments (bilirubin- yellow and biliverdin green) that are also excretory products,

(iii) The liver cells also eliminate certain other waste products like cholesterol, metal ions and waste-products of haemoglobin. These waste-products and bile pigments reach the duodenum through bile and pass out with faeces.

Function # 4. Glycogenesis:

It is the conversion of the excess of glucose into glycogen by liver cells with the help of insulin secreted by the pancreas.

Function # 5. Glycogenolysis:

It is the conversion of glycogen into glucose by the liver cells with the help of glucagon secreted by the pancreas.

Function # 6. Lipogenesis:

It is the conversion of excess of glucose and amino acids into fats.

Function # 7. Gluconeogenesis:

It is the formation of glucose or glycogen from non-carbohydrate sources such as amino acids, fatty acids, glycerol, etc. It also occurs in the kidneys and striped muscles.

Function # 8. Detoxification:

Liver converts toxic substances into harmless substances e.g., harmful prussic acid, formed during metabolism in all body cells, is neutralized and rendered harmless by liver cells.

Function # 9. Haemopoiesis:

The process of formation of blood corpuscles is called haemopoiesis, the liver produces red blood corpuscles in the embryo.

Function # 10. Synthesis is Blood Proteins:

The liver produces blood proteins such as pro-throm­bin and fibrinogen that help in the clotting of blood.

Function # 11. Secretion of Heparin:

Liver secretes heparin (anticoagulant).

Function # 12. Lymph Formation:

Liver is an important seat of lymph formation.

Function # 13. Synthesis of Vitamin A:

Liver synthesizes vitamin A from b-carotene. The latter is an orange-yellow substance of carrot.

Function # 14. Secretion of Enzymes:

Liver secretes certain enzymes which play important roles in the metabolism of proteins, fats and carbohydrates in the body.

Function # 15. Destruction of Red Blood Corpuscles:

The old worn out red blood corpuscles are broken down in the liver cells. Their haemoglobin is changed into bile pigments

Function # 16. Phagocytosis:

The Kupffer’s cells of the liver engulf the disease causing microor­ganisms, dead cells and foreign matter.

Function # 17. Osmoregulation:

Liver produces angiotensinogen (a protein) which helps kidneys in maintaining body fluid osmoregulation.

Function # 18. Production of Heat:

Due to high metabolic activities of the liver, enough heat is generated, which is essential for maintaining the optimum body temperature.

Function # 19. Storage:

Liver stores:

(i) Glycogen,

(ii) Fats,

(iii) Vitamins like A, D, E, K and B₁₂

(iv) Bile in the gall bladder,

(v) Blood

(vi) Water,

(vii) Iron, copper and potassium.