Digestion of Food in Human Body

The process of digestion of food begins in the mouth and is completed in small intestine.

Food in Mouth  -  In mouth starch is digested with the help of enzyme salivary amylase present in the saliva.

Starch Salivary amylase Maltose

Food in phayrx and esophagus -  No chemical digestion takes place in Pharyx and Esophagus.

Food in Stomch  -  Inside the stomach, food mixes with gastric juices which contain hydrochloric acid. Gastric juice kills bacteria and help in digestion of proteins with the help of 02 enzymes commonly known as Pepsin and Renin.

1) Pepsin acts on proteins and changes them to smaller molecules.

 Protein Pepsin  Proteoses + Peptones

2) Renin acts on milk protein casein and changes it to insoluble curd ( paracasein)

Casein Renin  Paracasein

Food in form of thick paste leaves stomach and moves to small intestine. This paste in called Chyme.


FOOD IN SMALL INTESTINE

Small intestine has 3 parts which are termed as duodenum, jejunum and ileum.

Duodenum : This part receives pancreatic juice from pancreas and bile from gall bladder.

Bile actually helps in breaking down the fats into tiny droplets.

It provides alkaline medium for action of enzymes.

Pancreatic Juice : It contains enzyme Trypsin and Lipase.

Trypsin : It acts on proteins proteoses and peptones and changes them to polypeptides

Proteins, proteoses and peptones Trypsin Polypeptides

Lipase acts on fats and change them to fatty acids and glycerol.  

Fats lipase fatty acids and glycerol

No chemical digestion takes place in Jejunum.

Ileum : In ileum following enzymes are present.

1) Erpsin

Peptones + Peptides   erpsin  amino acids

2) Maltase 

Maltose  maltase  glucose

3) Sucrase

Sucros    sucrase   glucose + fructose

4) Lactase

lactese   lactase  glucose + galactose

Digestion of proteins, fats and carbohydrates in completed in small intestine and they are absorbed in blood stream.