Absorption

Human nutrition is mainly based on digestibility. Digestibility means the ability to break down complex food materials into simpler food materials, which can be soluble in blood. Absorption refers to the process of accepting simpler, soluble food materials by different physical processes. Absorption is done in the small intestine, though a small amount of drugs is absorbed in the mouth, and water is absorbed in the large intestine. In the small intestine, some villi carry microvilli in their anterior part. These kinds of modifications in the wall of the small intestine increase the overall surface area for absorption. The villi are supplied with lacteals and blood vessels. The body, generally, absorbs the simpler food materials in dilute form.

Process of absorption

The process of absorption can occur by different physical processes like diffusion, facilitated diffusion, and active transport. Some amounts of monosaccharides, for instance, glucose, different amino acids, and a wide range of electrolytes are absorbed by the process of diffusion. Diffusion is dependent on concentration gradient and substances transferred by the process are very small in size. Other substances like amino acids and glucose are generally absorbed by the process of facilitated diffusion with the help of different carrier proteins. Water is absorbed in the large intestine by the osmotic gradient i.e. by the process of osmosis. Some glucose molecules and amino acids are transported along with sodium ions by active transport. In the case of lipids, it is emulsified to form micelles. These micelles are covered with a protein coat to form chylomicron. This chylomicron gets absorbed in the lacteals of villi in the small intestine. From lacteals, it is transferred into blood vessels.

Importance of absorption

Digestion deals with the breakdown of complex food materials into simpler food materials whereas absorption means acceptance of those simpler food materials by the body. Without absorption of nutrients by the human body through blood, the body would not be able to use the food materials.

For getting energy: Any living organism intake food for getting energy. After intake of food, absorption is equally important just like digestion. Without absorption of simpler food material by the body, assimilation of food would not occur. Therefore, the human body will not get energy as well by the process of catabolism. In the presence of oxygen, by the process of metabolism, the breakdown of simpler food materials occurs to release energy in the form of ATP.

For repairment of body cells: Absorption of nutrition is necessary for proper development and repairment of body tissues. The absorption of vitamins and minerals along with amino acids helps in the proper development of tissues. Worn-out tissues also get repaired with the absorption of this. Moreover, proper intake and absorption of minerals help to avoid mineral imbalance in the body and osmoregulation as well. Absorption of vitamins helps to avoid different vitamin deficiency diseases.

Maintenance of osmoregulation: Absorption of water is necessary. About 70% of the total body is water. It helps in the maintenance of osmoregulation in the body. Water also helps in repairing the tissues and body cells. Lubrication of body cells is also done with the help of absorption. 

Conclusion

Digestion deals with the breakdown of complex food materials into simpler food materials whereas absorption means acceptance of those simpler food materials by the body. Absorption is done in the small intestine, though a small number of drugs are absorbed in the mouth, and water is absorbed in the large intestine. In the small intestine, some villi carry microvilli in their anterior part. These kinds of modifications in the wall of the small intestine increase the overall surface area for absorption. The importance of absorption consists of repair of body cells, generation of energy, maintenance of osmoregulation, and so on.