Liver is one of the important organ of digestive system. It is also the largest visceral organ and gland of human body. It is 4 lobed in human. The main function of liver is secretion of bile juice. Beside the main function, liver also performs other functions in our body.
1. Function of liver in bile secretion
Secretion of bile is the major function of liver. Bile is the complex greenish alkaline fluid containing bile salts and pigments. Bile salt are sodium bicarbonate, sodium glycocholate and sodium taurocholate. While bile pigments consist of bilirubin and biliverdin which are breakdown undigested part of haemoglobin. The main function of bile is breakdown of larger fat molecules into smaller pieces called as emulsification of fat. It also destroys the harmful bacteria present in it. Bile is basic in nature which neutralize acidity of gastric juice and makes the food ready for further digestion.
2. Function of liver in digestive system
Liver plays great role in breakdown of fats and metabolism of carbohydrates. Metabolism of carbohydrate is processed in different ways by liver.
When hepatic portal vein carrying end product of digested food reaches liver, it withdraws excess sugar present in it. The excess sugar is converted into glycogen by liver cells and this process is known as glycogenesis. The formed glycogen is stored and used by cells when required.
When the required glucose amount is not supplied in the diet, the stored glycogen is converted into glucose to fulfill the required amount in the body. This process of conversion of stored glycogen into glucose by liver is called as glycogenolysis.
The conversion of non-carbohydrate source (like amino acid, fatty acids, glycerol) into glucose by liver is called as gluconeogenesis.
3. Function of liver in excretion
Liver helps in excretion of urea, cholesterol, heavy metals mainly mercury, arsenic, cadmium etc. The excess amino acids in the blood are removed by the process called deamination. Deamination is the process of breakdown of amino acids into carboxyl and ammonia groups by liver cells.
4. Functions of the liver in phagocytosis
Liver contains many phagocytosis cells called as Kupffer cells. It is also called as hepatic macrophages. Kupffer cells engulf and destroys bacteria, foreign particles and dead RBCs from blood.
Liver is primary site for detoxification of harmful substances and wastes. Detoxification is the process of conversion of highly toxic substances into low toxic substances by liver cells. This process prevent body from toxicity. Alcohol, drugs, ammonia etc. are detoxified by liver cells.
6. Synthesis of Enzymes, vitamins & proteins
Liver synthesis enzymes that are essential for metabolism of carbohydrate, protein and fats. It also converts β-carotene into vitamin A and plays important role in storage of vitamins A, D and B12. Proteins responsible for coagulating blood is also synthesis by liver.
7. Haemopoiesis & erythrociasis
Haemopoiesis is the process of formation of blood in body. During embryonic development of human, liver is the main site for formation of blood cells. But in adult it is shifted in bone marrow. Erythrociasis is the process of removal of old and damaged RBCs by the recticulo-endothelial cells of liver.
- Liver is the main site for blood formation in embryonic development of human.
- It contains phagocytic cells called Kupffer cells which engulf bacteria and foreign particles.
- It shows highest regeneration capacity.
- It carries both exocrine and endocrine functions.
- Bile juice secreted by liver does not contains any digestive enzymes.
- Bile juice secreted by liver is stored and concentrated in gall bladder.