Question

How does the length of the small intestine relate to its function in absorbing nutrients?

Answer 1

The processes of digestion include ingestion, digestion, absorption, assimilation, and defecation. The alimentary canal starts from the mouth and ends with the anus. The small intestine or small bowel is an organ in the gastrointestinal tract where most of the end absorption of nutrients and minerals from food takes place. It lies between the stomach and large intestine.

Complete answer:
Ingestion is the entry of food through the mouth. Here the food is broken down into smaller pieces with the help of teeth. The saliva gets mixed with food and helps the bolus to be easily swallowed. After which all through the alimentary canal the propulsion is through the peristaltic movement. Inside the stomach, the gastric juices are released which activate enzymes aiding in chemical digestion.
The chyme then moves into the small intestine. Here the food gets mixed with bile and pancreatic juice that further aids digestion. The main function of this organ of the gastrointestinal tract is the absorption of nutrients, vitamins, and bile salts. This is facilitated by the increased length of small intestines as the surface area is greatly increased. The walls of the small intestine also have vascular projections that further increase the surface area of absorption. 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 from the lumen of the intestine into these capillaries and lacteals. Amino acids, carbohydrates, and lipids are thus absorbed and assimilated by the body for the production of energy.

Note: Digested food passes into the blood vessels in the wall of the intestine through either diffusion or active transport. Absorption of the majority of nutrients takes place in the jejunum.