Functions of the Liver – Class 11 | Chapter – 16 | Biology Short Notes Series PDF

Functions of the Liver: The liver regulates most chemical levels in the blood and excretes a product called bile. This helps carry away waste products from the liver. All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down, balances, and creates the nutrients and also metabolizes drugs into forms that are easier to use for the rest of the body or that are nontoxic. More than 500 vital functions have been identified with the liver.

  • It is the largest gland of the body.
  • It generally weighs about 1.6 kg.
  • It is chocolate colored and is located just behind the diaphragm on the right side of the upper abdominal cavity.
  • The liver has two main lobes, the right lobe which is larger, and the left lobe along which is smaller with two small lobes, the quadrate lobe and the caudate lobe present behind the main lobes.
  • Hepatic artery supplies to the liver.
  • The blood is drained into the inferior venacava by the hepatic vein.
  • On the undersurface of the right lobe of liver, a pear-shaped structure is located called as a gall bladder.
  • The gall bladder serves as a reservoir that stores the bile juice secreted by the liver.
  • The right and left hepatic ducts from the liver join to form a common bile duct or ductus choledochus.
  • The common bile duct and pancreatic duct join to form the hepatopancreatic duct, near the duodenum.
  • This opens in the duodenum via an opening guarded by the sphincter of Oddi.
  • The dilation of short common hepatopancreatic duct forms hepatopancreatic ampulla or Vater’s ampulla.
  • The ampulla opens into the duodenum.
  • The bile duct is surrounded by a strong sphincter muscle of Boyden before it is joined by the pancreatic duct.
  • When there is no food in the duodenum, this muscle closes.
  • This forces the bile into the gall bladder through the cystic duct for storage.

Functions of the Liver

  • The liver being a multipurpose organ, performs several important functions:
  • Production of bile:
    • Liver secretes bile which is an alkaline dark green-colored fluid having several organic and inorganic salts as well as some waste substances.
    • The bile performs the following functions:
    • It makes the chyme alkaline, better suited for the action of pancreatic juice.
    • It is responsible for the emulsification of fats.
    • It helps in removing the excretory products like bile pigments, inorganic salts, toxins, etc. from the body.
    • It stimulates peristalsis.
    • Some bile salts are necessary for the absorption of vitamin K and other vitamins soluble in fats.
    • Bile acts as an antiseptic, therefore, it does not allow the growth and multiplication of bacteria.
  • Regulation of blood sugar level:
    • Liver regulates the blood sugar level (normal 90-120mg per ml of blood) either by the process of glycogenesis or by the glycogenolysis.
    • Glycogenesis is the conversion of glycogen into glucose by the liver cells with the help of glucagon secreted by the pancreas.
    • It is also a center for gluconeogenesis and glyconeogenesis.
  • Lipogenesis:
    • Liver also controls lipogenesis. The conversion of the excess of glucose and amino acids into the fats is termed as lipogenesis. It also takes place into the liver.
  • Deamination:
    • Liver decomposes the excess and harmful amino acids of blood into toxic NH3 and metabolically useful keto acids by the process of deamination in the presence of oxidase enzyme.
    • In the liver cells, toxic NH3 is combined with CO2 to form less toxic urea by the process of detoxification.
    • Liver also detoxifies the alcohol and converts it into acetaldehyde and then harmless acetyl CoA.
  • Absorption and metabolization of bilirubin:
    • Liver transforms hemoglobin of dead RBCs into bile pigments such as biliverdin and bilirubin which are egested out along with feces. Thus, liver helps in excretion.
  • Aids in blood clotting:
    • Liver produces an anticoagulant called heparin which prevents the coagulation in the blood vessels.
    • Liver produces two main proteins fibrinogen and prothrombin which help in clotting of blood at injury to check excess of bleeding.
  • Erythropoesis and hemolytic function:
    • Liver acts as an erythropoietic organ. It forms RBCs in the foetus.
    • Liver also acts as hemolytic organ. It breaks old RBCs.
  • Immunological functions:
    • Kupffer’s cells of liver act as phagocytes which feed on dead cells and bacteria by the phagocytosis process.
  • Vitamin and mineral storage:
    • Liver synthesizes vitamin A from beta carotene in the presence of an enzyme carotenase. Beta carotene is an orange yellow substance of carrot.
    • Liver stores minerals like copper and iron, vitamins like A, D, E, K and B12, glycogen, fats and water.
  • Maintains body temperature:
    • Liver is the major heat producing centre of the body. Because of high metabolic activities of the liver, sufficient heat is generated, which is very important for maintaining the optimum body temperature.
  • Blood reservoir:
    • It serves as the second reservoir of blood.
  • Angiotensinogen synthesis:
    • Liver secretes a protein called angiotensinogen which helps kidney to maintain body fluid, osmoregulation.
  • Blood filtration:
    • It helps in eliminating several unwanted substances like carbolic acid, cresol, etc. from the blood coming from alimentary canal.
    • It is the important seat of lymph formation.
    • It also produces certain substances which check anemia.

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By Team Learning Mantras