1.9 Storage and Metabolic Role of Liver

Anatomy and Blood Supply

The liver is a large, vital organ with a complex structure and a unique dual blood supply.

• Structure:

  • Composed of a larger right lobe and a smaller left lobe.
  • Lobes contain thousands of smaller functional units called lobules.
  • Lobules are connected to bile ducts, which transport bile from the liver to the small intestine.

• Dual Blood Supply: The liver receives blood from two distinct sources, ensuring it is supplied with both oxygen and nutrients from the digestive system.

Major Metabolic and Regulatory Functions

The liver performs over 500 vital functions, acting as the body's primary metabolic hub.

1. Digestion: Produces bile, which emulsifies fats in the small intestine, aiding digestion and carrying away waste products.

2. Protein Synthesis: Produces essential blood plasma proteins, such as serum albumin (maintains osmotic pressure), globulins (immune function), and fibrinogen (blood clotting).

3. Lipid Metabolism: Synthesizes cholesterol and special proteins that transport fats throughout the body.

4. Carbohydrate Metabolism: Regulates blood glucose levels by converting excess glucose into glycogen for storage (glycogenesis) and converting glycogen back to glucose when energy is needed (glycogenolysis).

5. Amino Acid Regulation: Monitors and regulates the blood levels of amino acids, the building blocks of proteins.

6. Storage and Recycling: Processes hemoglobin from old red blood cells to recycle its iron content, which is then stored in the liver.

7. Detoxification (Urea Cycle): Converts toxic ammonia (a by-product of protein metabolism) into urea, a less toxic substance that is excreted by the kidneys. This is a critical part of the body's excretory system. Functions Of Kidney→

8. Detoxification (General): Clears the blood of drugs, alcohol, and other poisonous substances by metabolizing them into non-toxic or easily excretable forms.

9. Blood Clotting: Produces key proteins and factors necessary for regulating blood clotting.

10. Immunity: Resists infections by producing immune factors and removing bacteria from the bloodstream.

11. Waste Removal: Clears bilirubin (a breakdown product of red blood cells). Failure to do so leads to an accumulation, causing jaundice (yellowing of the skin and eyes).

Excretion of Waste Products

After the liver breaks down harmful substances, the by-products are excreted:

• Via Bile: By-products enter the intestine and are eliminated in the feces.
• Via Blood: By-products are filtered from the blood by the kidneys and eliminated in the urine.