The Liver and Its Functions

The liver is a large reddish-brown organ with two lobes. It lies just below the diaphragm to the right side, partly overlapping the stomach. Its average weight is about 1.25kg. Each lobe of the liver is subdivided into smaller lobes 


[image credit: Bruce]

The gall bladder which stores the bile is connected to the duodenum by a short tube called bile duct. The bile duct is a soft organ with a rich and extensive blood supply.


FUNCTIONS OF THE LIVER

The liver performs the following functions in the body:

1. Regulation of blood sugar: The liver converts excessive glucose in the blood to glycogen. This process is stimulated by the hormone called insulin, which is  secreted by the pancreas. The glycogen is stored in the liver. 

Conversely, when the blood glucose level falls below normal, glycogen is converted back to glucose under the influence of another hormone called glucagon.

2. Regulation of blood protein: The body cells cannot store excess amino acids in the body. The liver therefore breaks down excess amino acids. The process is called deamination. 

Deamination is the process by which excess amino acids are broken down into its components:

1. the amino group, which is poisonous and toxic, is converted into harmlessn urea and excreted
2. the carboxyl group, which is processed into carbohydrates and stored in the liver as glycogen

3. Detoxification: The liver converts poisonous and toxic materials such as drugs, alcohol,  etc. in the body into harmless substances which are later excreted.

4. Production of bile: The liver produces bile which is stored in the gall bladder and secreted into the duodenum when needed. The bile aids emulsification of fats which enhance its digestion and absorption. The bile contains:

1. cholesterol
2. inorganic salts
3. bile salts which aid in fat digestion
4. a yellowish pigment, bilirubin, an excretory product formed during the breakdown of haemoglobin from worn out red blood cells.

5. Formation and breakdown of red blood cells (erythrocytes): In the foetus, the liver forms the red blood cells (erythrocytes). In adults, together with the spleen, the liver breaks down worn out red blood cells.

6. Production of heat: The numerous activities of the liver generate heat as a by-product, which helps to maintain the body temperature.

7. Storage/reservoir of blood: The liver acts as reservoir of blood as it contains many capillaries and blood spaces with large volume of blood.

8. Storage of vitamins and minerals: The liver store the fat soluble vitamins A, D, E, and K, as well as water soluble vitamins B and C. 

9. Storage of iron: The liver stores iron obtained from the breakdown of red blood corpuscles..

10. Inactivation of hormones: The liver inactivates the body's hormones, thus ending their period of activity. The activities of certain hormones like testosterone are rapidly destroyed, those of others like insulin are destroyed more slowly. Thus, the liver exerts a homeostatic effect on the activities of the hormones.

11. Regulation of lipids: The liver also removes lipids from the blood, converts them to glucose and oxidizes them to release energy during aerobic respiration.

Also read: Diseases of the Liver, their Effects and Remedies

Categories: Biology, Excretion, Excretory System, Homeostatis, The Liver