Question

Explain the digestion in the small intestine.

Answer 1

Hint: During digestion, the small intestine is the main site of enzyme production and nutrient absorption. To help with chemical breakdown, enzymes from the liver and pancreas are added to the duodenum of the small intestine; the resulting chyme is transferred into the large intestine through peristalsis via the jejunum and the ileum.

Complete Answer:
Chyme passes from the stomach to the small intestine: the organ where the absorption of protein, fat and carbohydrates is done.A long tube-like organ with a highly-folded surface containing finger-like projections is the small intestine: the villi. There are several microscopic projections on the apical surface of each villus: the microvillus.

To allow the nutrients from the digested food to be absorbed into the bloodstream on the other side, these structures are lined with epithelial cells on the luminal side. The villi and microvilli increase the surface area of the intestine with their many folds and increase the absorption rate of the nutrients.

The thin, more than 6 m long, human intestine is divided into three parts: the duodenum, the jejunum, and the ileum. The C-shaped, fixed part of the small intestine, the duodenum, separates the pyloric sphincter from the stomach, which opens to allow the chyme to move from the stomach to the duodenum, where it mixes with pancreatic juices.

The alkaline solution is rich in bicarbonate, which neutralises the chyme's acidity and functions as a buffer. The duodenum is penetrated by digestive juices from the pancreas, liver, and gallbladder, as well as from gland cells of the intestinal wall itself. There the absorption of fatty acids also takes place.

The jejunum is considered the second section of the small intestine. Here, nutrient hydrolysis continues as the intestinal lining consumes much of the carbohydrates and amino acids. The majority of chemical digestion and the absorption of nutrients occurs in the jejunum.

The latter portion of the small intestine is the ileum. It is here where the blood stream is absorbed by bile salts and vitamins. The undigested food is sent through the ileocecal valve through peristaltic motions of the muscle from the ileum to the colon. The vermiform, worm like, appendix is located at the ileocecal valve. The human appendix secretes no enzymes and has a marginal function in immunity.

In the small stomach, the digestion of food is done. The undigested food moves to the large intestine for absorption after passing through the small intestine.

Note: The small intestine is the longest portion of the digestive tract, about three times the length of the body. 90% of our nutrients are absorbed by your body into your blood through the small intestine. Your gastrointestinal tract contains the highest amounts of serotonin in the body, a hormone that helps stabilise your mood and lets you sleep better.