DIGESTION IN HUMAN & ROLE OF LIVER

DIGESTION IN HUMAN:
                            Our cells require oxygen, water, salts, amino acids, sugar, fatty acids, and vitamins. These can cross cell members to enter cells. Amino acids, simple sugars and fatty acids are rare our environment. Such substances are usually parts of larger molecules like proteins, polysaccharides and lipids, which cannot cross the membranes. There is a need of converting such large and non-diffusible molecules into smaller and diffusible molecules. This is achieved through the process of digestion.

After digestion the diffusible molecules from the digestion system reach body cells through blood. Here they are assimilated. At the same time, the indigestible part of food is assimilated. At the same time, the indigestible part of food is eliminated out of body through the process of defecation. In simple ways , the nutrition in humans comprises of following phases.

1.       Ingestion: The process of taking in food.

2.       Digestion: The process of breaking up complex substances into simpler substances.

3.       Absorption: Diffusion of digested food into blood and lymph.

4.       Assimilation: Conversion or incorporation of absorbed simple food into the complex substances constituting the body.

5.       Defecation: Elimination of undigested food from the body.

ROLE OF LIVER:

            Liver is the largest gland of our body. It is multi-lobed and dark reddish in appearance. It lies beneath the diaphragm on the right side of abdomen. In adult human, its weights about 1.5kg and is the size of football. A pear-shaped greenish yellow i.e gallbladder lies along the right lobe of liver on ventral side.

Liver secretes bile, which is stored in gallbladder. When gallbladder contracts,  bile is released into duodenum through common bile duct. Bile has no enzymes but contains bile salts for the emulsification of lipids. It helps the lipid-digesting enzymes to attack on lipids. Liver carries out a number functions some of which are summarized here;

1.       Removes amino groups from amino acids

2.       Converts glucose into glycogen and break glycogen into glucose.

3.       Converts ammonia to less toxic from; urea

4.       Destroys the old red blood cells.

5.       Manufactures blood clotting proteins called fibrinogen.

6.      Converts carbohydrates and protein into lipids and produces cholesterol.

7.       Produce heat to maintain body temperature.

 Stores fat-soluble vitamins and mineral ions, such as iron.