Question

Where & how the digested food is absorbed in human beings.

Answer 1

Absorption of the digested food: 

• There is the absorption of the digested food in the ileum into the blood with the help of active transport. 
• The villi provide an increased surface for the absorption. The Millikin in hormone enhances absorption by increasing villi movements. 
• There is about 45 lakh of villi in the ileum of human beings.
• The monosaccharides (glucose, galactose, fructose, mannose etc.) are absorbed directly into the blood by active transport in the presence of water. 
• The amino acids are also absorbed directly into the blood by active transport.
• Alcohol is absorbed by diffusion in the whole alimentary canal.
• The fatty acids before the absorption form an emulsion in the presence of bile salts which is called micelles. 
• These micelles are taken up by the epithelial cells with the help of pinocytosis.
• The epithelial cells pack these fatty acids in small packets which are called chylomicrons.
• The diameter of the chylomicron is about 1µ. The chylomicrons are released into the lacteals by exocytosis. 
• The chylomicrons from the lymph reach into the blood at the junction between subclavian & jugular veins. 
• The water-soluble vitamins are absorbed directly into the blood by diffusion.
• Absorption of the vitamin B₁₂ needs the presence of a castle factor. 
• Fat-soluble vitamins are absorbed with the help of bile salts like the absorption of the fatty acids