The Human Liver

LIVER – Central Metabolic Station:

No doubt, ALLAH ALMIGHTY has made the human body most complex and developed than all the other creatures of the world. All the functions and structures of the human body are well-coordinated and regulated. Glands play an important role in this coordination. And, Liver is one of these glands. It is the largest gland of the body, which performs a wide range of crucial functions. It is also called Central Station of Metabolism.

Location:

Liver is situated just beneath the diaphragm (rib cage) and the top of stomach, right kidney and intestines, at the right side of abdomen.

Structure:

• Shape: Human Liver looks like a wedge, cone or flattened football in shape.
• Color: It is dark reddish-brown in color.
• Weight: It weighs about 4 pounds (average) in men and 3 pounds (average) in women.
• Cells: Liver consists of four major types of cells i.e., Hepatocytes (HCs), Kupffer cells (KCs), Hepatic stellate cells (HSCs) and Liver sinusoidal cells (LSECs). All these cells cooperate with each other in order to maintain liver’s shape and functions.
• Functional Unit: The functional unit of liver is Hepatic Lobule. Each hepatic lobule is a hexagonal structure and consists of hepatocytes and portal triad.

Functions:

1. Storage: Storage is one of the most important function of liver. It stores glycogen and various minerals such as iron and calcium. When the level of glucose falls down in our blood, glucagon (a hormone released from the alpha cells of Islets of Langerhans) acts on liver converts glycogen into glucose. Similarly, when the level of glucose in our blood rises up to the normal value, insulin (a hormone released from beta cells of Islets of Langerhans) converts glucose into glycogen and stores in liver for later use.
2. Recycling: It is involved in the recycling of old RBCs to new RBCs.
3. Detoxification: Detoxification is another pivotal role of liver. It detoxifies various harmful chemicals e.g., food additives, pesticides, drugs etc. that enter into the human body.
4. Conversion: It converts various compounds from one form to another. It converts glucose into glycogen and vice versa, with the help of pancreas. Moreover, it also converts lactic acid into glycogen.
5. Bile secretion: Liver secretes bile to help digestion. Actually, bile is a greenish fluid. This greenish fluid is composed of bile salts (Sodium glycocholate – C₂₆H₄₃NO₆.Na and Sodium taurocholate – C₂₆H₄₄NO₇Na), cholesterol, lecithin, cellular debris, mucus and bile pigments (bilirubin and biliverdin – formed from the catabolism of hemoglobin). These bile salts help in the emulsification of fats in small intestine.
6. Help in Excretion: Liver support the excretory function of the kidney by deodorizing many chemical poisons and harmful compounds and produce nitrogenous waste products i.e., ammonia, urea and uric acid from the nitrogen of amino acids.
7. Metabolism: As discussed above, it helps in body metabolism.
8. Plasma Protein: Liver synthesizes protein i.e., Albumin for plasma. This protein maintains osmotic balance of blood. It also helps in transport of hormones, drugs and fatty acids.
9. Blood Clotting Proteins: It also produces Prothrombin and fibrinogen proteins, which helps in blood clotting.