Define Nutrition In Human Beings OR Digestion in Human Beings

Updated on Jan. 8, 2021 03:23 PM IST by Lakshmi Arya

Digestive system of human consists of alimentary canal or gut and some accessary digestive organs.

  1. Alimentary canal : a long(6-9 meter) , coiled and muscular tube extending from mouth to the anus, consists of many specialised sections.
  2. Arranged sequentially, these are mouth,oral or buccal cavity, pharynx, oesophagus, stomach, small intestine,large intestine, rectum and anus.
  3. Buccal cavity: It has cheeks , tongue and teeth which helps in crushing the food and mix it with the saliva ( salivary amylase) secreted by the salivary glands. saliva wetted the food to make its passage smooth in the alimentary canal.
  4. Pharynx: part of the throat behind the mouth and nasal cavity, the tube going down to the stomach.
  5. Oesophagus: a muscular tube connecting pharynx with the stomach. It is also called food pipe.
  6. Stomach: most distensible part,thick, muscular,J-shaped organ present on the left side of upper part of abdominal cavity. It consists of four parts a)cardiac stomach b) fundus c) Body d) pyloric entrum. Stomach helps in mechanical churning and chemical digestion of food.
  7. Small Intestine: longest part (6meters) , narrow, tubular, divided into three parts.a). Duodenum b) jejunum c)  Ileum.         Small Intestine is the main region where digestion and absorption of food takes place.
  8. Large Intestine: also called colon , consists of three parts a) caecum b) colon c) rectum. Caecum ends into a tubular structure called vermiform appendix. It is a vestigial organ as they are not involved in cellulose digestion. Colon helps in conservation of water and minerals and formation of faeces.
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