Defaecation

9.5 Defaecation 
 
Function of The Large Intestine
  • After the absorption of nutrients is completed in the ileum, undigested food, dead cells, epithelial cells, fibre and water enter the large intestine and move slowly through peristaltic action.
  • Fibre consists of cellulose walls of plant cells.
  • The large intestine carries out two main functions:
    • absorption of water and vitamins.
    • formation of faeces.
Absorption of Water and Vitamins
  • Substances absorbed are water, mineral salts, metabolic byproducts of some bacteria such as vitamin B, vitamin K and folic acid.
Formation of Faeces
  • After the water is absorbed, the remaining waste is a semisolid called faeces.
  • Faeces contains dead cells from the inner layer of the intestine, waste products such as bile pigments, bacteria and toxic substances.
  • The walls of the large intestine secrete mucus to smoothen the movement of faeces until the anus.
  • The movement of faeces takes about 12 to 24 hours before entering the rectum.
  • The faeces will accumulate in the rectum until the pressure in the rectum increases and triggers the need to expel faeces from the body.
  • The rectum muscles will contract to expel faeces from the anus.
  • This process is called defaecation.
 
 

Defaecation

9.5 Defaecation 
 
Function of The Large Intestine
  • After the absorption of nutrients is completed in the ileum, undigested food, dead cells, epithelial cells, fibre and water enter the large intestine and move slowly through peristaltic action.
  • Fibre consists of cellulose walls of plant cells.
  • The large intestine carries out two main functions:
    • absorption of water and vitamins.
    • formation of faeces.
Absorption of Water and Vitamins
  • Substances absorbed are water, mineral salts, metabolic byproducts of some bacteria such as vitamin B, vitamin K and folic acid.
Formation of Faeces
  • After the water is absorbed, the remaining waste is a semisolid called faeces.
  • Faeces contains dead cells from the inner layer of the intestine, waste products such as bile pigments, bacteria and toxic substances.
  • The walls of the large intestine secrete mucus to smoothen the movement of faeces until the anus.
  • The movement of faeces takes about 12 to 24 hours before entering the rectum.
  • The faeces will accumulate in the rectum until the pressure in the rectum increases and triggers the need to expel faeces from the body.
  • The rectum muscles will contract to expel faeces from the anus.
  • This process is called defaecation.