Question

Short / Long answer type questions.
How does the absorption of nutrients take place? Discuss the role of blood and lymph vessels

Answer 1

Most of the nutrients are absorbed in the small intestine. The surface of the small intestine is lined by numerous finger-like projections called villi. The individual epithelial cells also have finger-like projections known as microvilli. The function of the villi and the microvilli is to increase the amount of surface area available for the absorption of nutrients. Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients such as carbohydrates and amino acids from the lumen of the intestine into these capillaries and lacteals (lipids). The nutrients are absorbed by processes of simple/passive diffusion, facilitated diffusion, and primary active transport, or secondary active transport. Among the nutrients, lipids may undergo passive or simple diffusion, short-chain fatty acids undergo simple diffusion, amino acids and glucose undergo active transport, and fructose is absorbed by facilitated diffusion. Most fats and fatty acids are actually absorbed in the lymphatic system first before being transported into the blood. Lymphatic vessels then transport the fats into the bloodstream. The absorbed substances are transported via the blood vessels to different organs of the body.