The large intestine is composed of a caecum, colon and rectum.
The caecum is a blind sac. It projects from large intestine between ileum and colon. A finger like process arises from the blind of the caecum. It is called appendix. Sometimes food entraps in the appendix. The decay of this food causes inflammation of the appendix. This inflammation of the appendix is called appendicitis. In some case, such inflamed appendix has to be removed surgically.
It is the largest part of the large intestine. It has three parts: an ascending part, a transverse part and a descending part. Colon opens into rectum.
It is the last part of the large intestine. Feces are temporarily stored in the rectum. Finally these feces are removed through anus at internals. Anus is surrounded by two sphincters. The internal is smooth sphincter, while the outer sphincter has stripped muscles. As the rectum fills with feces, it gives rise to defecation reflex. This reflex can be consciously inhibited in adults. But it cannot be controlled in the infants. Gradually, the child learns to bring this reflex under control.
Function of the large intestine
It performs the following functions:
1. Absorption of water and salts
The material that passes from the small intestine to the large intestine has a large amount of water, dissolved salts and undigested material. Most of the water and salts are absorbed into blood. There can be two abnormalities in the absorption of water.
- Diarrhea: If the absorption of water does not take place, it causes diarrhea. Diarrhea may be caused due to infection, drug action or emotional disturbances. If diarrhea remains unchecked it may cause dehydration. Such condition may be fatal.
- Constipation: It is other extreme condition. In this case, excessive water is absorbed.
2. Synthesis of Vitamins
A large population of bacteria lives inside the large intestine. These bacteria synthesize some vitamins especially, vitamin K. This vitamin k is absorbed by the blood and used in the body.
3. Removal of feces
The feces are also removed by the large intestine through anus. Feces contain a large number of bacteria, plants fibers, broken mucosal cells, mucous, cholesterol, bile pigments and water.