Small Intestines - Center of Digestion its Function and Disorders

Small Intestines : The Center of Digestion

Dr.Surya Rao Poodipeddi profile Authored by Dr.Surya Rao Poodipeddi on 24 Feb 2014 - 11:46.

The small intestines is the longest part of the digestive system, around 24 feet long when stretched to it full length. It begins where the stomach ends and ends where the large intestine begins. It stays coiled in order to get accommodated in the abdominal cavity. This tubular organ, 2.5cms.in diameter, is where most of the chemical digestion and absorption takes place. It is bounded on its sides by the ascending and descending colon and above by the transverse colon, all of which make the large intestine that begins where the small intestine ends.

The three most important parts of the small intestines are the duodenum, jejunum and the ileum.
All the food we eat leaves the stomach through the pyloric sphincter and enters the small intestine into the duodenum which is a C-shaped shortest section of the small intestine. It is in the duodenum where the true absorption begins. The other portion of the small intestine, the jejunum is where majority of absorption takes place. The last section of the small intestine, the ileum also has slight absorption function (Vitamin B-12 is absorbed in this part of the intestine) but mainly acts as a passage for the food to the large intestine.
Functions of the small intestines: The small intestines are very long with many folds in its lining. Millions of fingerlike projections called villi cover the entire lining of the intestine. The epithelial cells which make up the intestinal lining have brush orders.
When food is present in the small intestines, it is constantly in motion and the movements are fashioned to squeeze chyme (mixture of food particles) through the intestine, mix the chyme with the digestive enzymes present in it, mechanically breakdown the food particles and speed up the process of absorption of the end products of digestion by remaining in constant contact with the walls of the intestine.
The chyme mixes with pancreatic juice (produced by the pancreas), bile (from the liver), intestinal juices (secreted by the glands in the walls of the small intestines). The enzymes present in these secretions break down the semi-solid foods into smaller particles that can be easily absorbed through the lining of intestines into the blood stream.
All the foods we eat consists of three proximate principles namely carbohydrates, proteins and fats. The carbohydrates are broken into simpler sugars, the proteins into amino-acids and the complex fats are broken down to fatty acids and glycerol with the help of enzymes form pancreas and bile from the liver. Simple sugars, amino acids, vitamins electrolytes like sodium, potassium & chlorides, water and minerals are absorbed through the wall of the small intestines into the blood stream.
The pancreas plays a vital role in the digestion and absorption of food we eat. It secretes enzymes namely, amylase, protease, trypsine, chymotripsine and lipase. These enzymes in association with the intestinal enzymes peptidase and maltase complete the process of digestion and absorption. Sodium bicarbonate present in the pancreatic juice acts as a neutralizer and maintains optimum pH.
Disorders of the small intestines include:
Each of these diseases are attended on a case-to-case basis.
To sum up, the small intestines is where molecules of carbohydrates, proteins and fats from the food we eat are broken down into respective end products of digestion in the small intestines. Carbohydrates are broken into simple sugars, proteins into amino acids and fats into fatty acids and glycerol. It acts as a vehicle for transport of the food particles, broken down in its lumen by several enzymes and juices and finally, and is a major organ for absorption of the end products into the blood stream for energy supply.

 

*Disclaimer: This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.