decribe how carbohydrates,proteins & fats get digested in different parts of the alimentary canal

• Digestion of carbohydrates − mouth and small intestine
• Digestion of fats − small intestine
• Digestion of proteins −  stomach and small intestine

Digestion in mouth

• Saliva contains enzymes salivary amylase, lysozyme, and electrolytes.

• Salivary amylase basically helps in carbohydrate (starch) digestion up to 30%.
  

Digestion in stomach

Gastric juice secreted in stomach contains HCl, pepsinogen, rennin, and lipase. 

Proenzyme pepsinogen Pepsin (active enzyme)

Mucus and bicarbonate lubricate the gastric epithelium and protect it from action of HCl. Small amount of protein digestion (by pepsin) occurs here.

Digestion in Small Intestine

• 3 types of secretions are released into the intestine.

	Pancreatic juice released by hepatopancreatic duct	Bile	Intestinal juice (succus entericus)
1.	Contains inactive enzymes such as trypsinogen, chymotrypsinogen, procarboxypeptidase, amylase, lipase, nuclease, etc.	Contains bile pigments (Bilirubin and biliverdin), bile salts, cholesterol phospholipids	Contains enzymes such as maltase dipeptidase, lipase nucleosidase, etc.
2		Bile contains no enzyme.	Also contains mucus which in combination with bicarbonates released by pancreas provides alkaline medium and prevents intestinal mucosa from acid
3.		It emulsifies fats into micelles and activates  lipases.

Digestion of fats takes place in the small intestine with the help of bile juice which acts as emulsifier and breaks down the larger fat droplets into smaller ones. They are then acted upon by lipase enzyme found in pancreatic juice and intestinal juice which convert them into monoglycerides and fatty acids respectively.