Question

Amino acids are absorbed in
A. Blood capillaries of villi
B. Wall of the rectum
C. Lacteals and blood capillaries of villi
D. Lacteals of villi

Answer 1

Hint: Absorption is the process by which end products obtained through digestion enters the blood through the intestinal mucosa. The end product of protein digestion is an amino acid. The amino acid is passed into the bloodstream through the capillaries of tiny finger-like projections.

Complete answer:
For the process of absorption of amino acid, first, the proteins are digested into smaller and simple molecules (amino acids) which are then absorbed by the intestine. The digestion of proteins starts in the stomach where the proteolytic enzyme pepsin of gastric juice is activated which converts proteins into proteases and peptones.

Rennin is also present which helps in the digestion of milk proteins. Digestion of protein is completed in the small intestine by the enzymes of intestinal and pancreatic juice which convert peptones and proteoses into dipeptides which further is broken down to amino acid. This the end product of protein digestion is an amino acid. After digestion, absorption of amino acid takes place in the small intestine which is a principal organ for the absorption of nutrients.

The capillaries of villi collect the amino acid and sugars taken up by the villi into the bloodstream through diffusion. Villi are meant for absorption in the small intestine. Also, lacteals of villi take up chylomicrons (smaller particles of fatty acids and glycerol coated with fat globules).

So, the correct answer is option (A).

Note: Proteins are digested and broken down into smaller and simpler molecules which are amino acids. The amino acids (the end product of protein digestion) are then absorbed in the intestine through the capillaries of villi by the process of diffusion.