Microbial activities in intestine and stomach

• Different microbial enzymes act on carbohydrate, protein ,fat, etc in stomach and small intestine

Digestion of carbohydrate

• In stomach, carbohydrate digestion don’t occur
• Smaller chain of carbohydrate which is broken by salivary amylase passes from stomach where digestion do not occurs.
• After maintaining P^H,that bolus enters duodenum where pancreas secret some enzyme which help in digestion of carbohydrate
• Pancreatic amylase breakdown polysaccharides into disaccharides and oligosaccharides.
• Now, these disaccharides are converted into monosaccharide by maltases.
• Sucrases and lactoses secreted by brush border lining of intestinal wall acts on disachharides and convert them into glucose form.

Digestion of protein

• After mechanical breakdown in mouth, bolus enters stomach.
• In stomach protein digestion occurs.
• Pepsin and HCl secreted by stomach convert protein into large polypeptides.
• From stomach,chyme travels near small intestine where pancreas secrets digestive enzymeswhich convert polypeptides into further smaller peptides.
• Before digestive enzymes, Cholesystokinin and secretin secrets bicarbonate so that that optimum P^H is maintained.

 Digestion of fat

• At first, fat digestion occurs in rumen of stomach. Here glycerol is break down into fatty acids and sugars by hydrolysis.
• Similarly, unsaturated fatty acids are converted into saturated fatty acid by hydrogenation.
• In small intestine large masses of fat are breakdown into smaller segments by bile salt and phospholipid. Pancreatic lipase breakdown fats into monoglycerides and fatty acids.
• Bile salts and lipids form smaller lumps called micelles which emulsify fats.
• Micelles transport monoglycerides and fatty acids into enterocyte cell and diffuse across the membrane.
• Now in enterocyte cell monoglyceride converted back into triglycerides. This triglyceride with some lipids formchlymicrons and transport towards blood capillary and lymph capillary.