Ileum of the small intestine merges in the large intestine. There is an ileocaecal valve at the junction which guards the entry of food in the large intestine. The large intestine is about 1.5mts long and is subdivided into the following parts:
The caecum: it is the first part of the colon, ileocaecal junction is guarded by ileocaecal valve which does not allow the food to travel back to the small intestine. The vermiform appendix is a fine tube closed at one end which leads to caecum and is around 8 to 9 cm long and contain more lymphoid tissue.
The ascending colon: this passes upward from the caecum to the level of the liver where it curve left at the hepatic flexure to become transverse colon.
The transverse colon: it lies transversely below the stomach, it reaches to the left, below spleen to merge with the descending colon.
The descending colon: this passes down the left side of the abdominal cavity then curves down the midline. After it enters the true pelvis it is known as sigmoid colon.
The sigmoid colon: this part describe the s shaped Karur in the pelvis that continues downloads to become the rectum.
Functions of large intestine;
Absorption of water and formation of solid stool.
Absorption of glucose, amino acids, and certain drugs.
Mucus is secreted by the goblet cells of the large intestine. This prevents mechanical irritation and act as lubricant, making the reactions alkaline and lessening the acidity of bacterial fermentation.
Heavy metals are excreted from the blood directly into the colon and are passed out in the faeses.
The colon contains established microflora it helps in the synthesis of folic acid, vitamin b12 (cyanocobalamin) vitamin B and vitamin k absorption of fat soluble vitamins take place in large intestine.
Microbes present in the colon digest other pathogenic microbes and virus prevent infection.
Large intestine normal peristalsis pushes the faeses forward mass peristalsis occurs in the large intestine and this finally pushes the stool in the rectum.