Food is essential for
living. The nutrients in the food are what keep the body
functioning. But, the food needs to be broken or digested in order
for the body to use them. This process of digestion or break down of
food is achieved by the Digestive System.
The digestive system includes of
Mouth, Pharynx (throat), Oesophagus, Stomach, Pancreas, Liver, Gall
Bladder, and Intestines (small and large).
Process of Digestion:
The complete processing of food can take anywhere from 24-48 hours
to complete. There are 4 steps-
- Ingestion-
- The food or drink is taken from the mouth.
- Digestion-
- This process starts from the time we eat.
- The teeth undertake the first part of digestion i.e. mechanical by chewing.
- The crushing, and mixing is done by the stomach and the chemical action is undertaken by the enzymes.
- Absorption-
- The simple broken down nutrients molecules get absorbed into the blood stream, which are then carried to the needed place.
- Egestion-
- The undigested food, which is useless for the body is thrown out in the form of Feces. This happens from the anus.
- Mouth (size 3 inch; time taken by food 5-30 seconds) - food mixes with saliva and makes it easy to swallow.
- Pharynx and Oesophagus (size 10 inch; time taken for swallowing 10 seconds) - the back of the tongue pushes the food, and the muscles push it down through the oesophagus.
- Stomach (size 6 inch; time taken for initial breakdown 3 hours )- the stomach expands as we eat to hold all the food that is eaten. The semi-digested food is passed from the stomach to intestines in about 2.5 to 3 hours.
- Small Intestine (size 13-16 feet; time taken 3 hours) - here the food mixes with enzymes and emulsifiers and becomes thick milk-shake like. The digested part of the food gets absorbed here. The food travels along the three parts of small intestine: from the duodenum to jejunum and then to ileum.
- Large Intestine (size 4 feet; time taken up to excretion 2 days) - water and minerals are absorbed here. Faces accumulate in the last part or the rectum till it is excreted via the anus.