Question

How does the structure of the small intestine help the small intestine to absorb nutrients?

Answer 1

An organ in the gastrointestinal tract where much of the final absorption of nutrients and minerals from food takes place in the small intestine or small bowel. It lies between the stomach and the large intestine and, through the pancreatic duct, obtains bile and pancreatic juice to help digestion.

Complete answer:
There are three distinct regions in the small intestine: the duodenum, jejunum, and ileum. The shortest duodenum is where preparation starts for absorption by small finger-like protrusions called villi. The jejunum is specialized for absorption by its enterocyte lining: small particles of nutrients that have been previously digested in the duodenum by enzymes. The main purpose of the ileum is to absorb vitamin B12, bile salts, and whatever digestive products the jejunum has not absorbed. There is a finger like projections called villi in the internal lining of the small intestine. The surface of the villi is lined with microvilli cells.
The cells have tiny hairlike structures called microvilli on villi. This helps increase each cell's surface, ensuring that more nutrients can be consumed by each cell. Both villi and microvilli increase the surface area of certain nutrient absorption folds in the small intestine.
Also, blood capillaries and lymphatic vessels are within the villi, where nutrients are filled after absorption. Monosaccharides and amino acids enter the blood stream while fatty acids and glycerol enter the lymphatic system. Thus, in this way the structure of the small intestine using villi helps the small intestine to absorb nutrients.

Note:
The small intestine's inner surface is not smooth, but has circular folds. This not only increases the area of the surface but also helps control the flow through your intestine of digested food. While the small intestine is shorter than the large intestine, the digestive tube is the longest segment, reaching an average of around 22 feet (or seven meters) or three-and-a-half times the length of the body.