MECHANISM OF DIGESTION PRESENTED BY - PowerPoint Presentation

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MECHANISM OF DIGESTION

PRESENTED BY

MISS SUBHAPRADA LENKA

Lect. In Zoology

Khemundi

College,

Digapahandi

DIGESTION

Digestion is a process by which the complex & insoluble form of food material converted into simple & soluble form by physical & chemical processes.

Carbohydrate Glucose

Proteins Amino acids Fats Fatty acids+Glycerol

ORGANS OF THE DIGESTIVE SYSTEM

1.DIGESTION OF CARBOHYDRATES

In Mouth-

Salivary gland secretes ptyalin which converts boiled starches to maltose & glucose polymers.

Starches Maltose+Glucose polymerIn Stomach-In stomach ,the medium is acidic &action of Ptyalin is stopped by HCL.

Only 5% of starch is hydrolysed by HCL.

In Smallintestine-

Pancreatic secretion contains a large quantity of pancreatic amylase which converts starches to disaccharides(sugars).

Starches Maltose+Sucrose+Lactose

+Glucose polymersIn microvilli of small intestine-The enterocytes lining the villi of the small intestine contains 4 enzymes i.e lactase ,sucrase,maltase & dextrinase which splits Disaccharides to monosaccharides mainly glucose.

Lactose Galactose Glucose

Sucrose Fructose Glucose

Maltose Glucose

Glucose polymers Glucose

2.DIGESTION OF PROTEINS

In mouth-

There is no digestion of proteins in mouth cavity.

In Stomach-In stomach ,gastric glands are present which secretes HCL,pepsin & renin.Pepsinogen pepsinProteins proteoses+peptones+polypeptides

Prorenin ReninCaseinogen CaseinCasein Calcium paracasein

Calcium paracasein peptones+proteoses

In Small Intestine-

Most protein digestion occurs in the upper small intestine,duodenum & jejunum ,under the influence of proteolytic enzymes from pancreatic secretion.The major proteolytic pancreatic enzymes trypsin,chymotrypsin.

Trypsinogen Trypsin

Peptones +proteoses Polypeptides Chymotrypsinogen chymotrypsin Paracarboxypeptidase CarboxypeptidaseProteoses+peptones+polypeptides Peptides

+Amino acidsProteins Dipeptides+Tripeptides

In Microvilli of Small intestine-The last digestive stage of the proteins in the intestinal lumen is achieved by the enterocytes that line the villi of the small intestine mainly in the duodenum & jejunum.

Polypeptides Dipeptides+Tripeptides

+Amino acids

Dipeptides Amino acidsTripeptides Amino acids

3.DIGESTION OF FATS

There is no digestion of fats occurs in mouth cavity & stomach.

In Small intestine-

Bile salts are formed in the hepatic cells . Bile plays an important role in fat digestion.It helps to emulsify fats. Fats Emulsified fats

Emulsified fats Fatty acids+Glycerol

In microvilli of Small intestine-Tryglycerides Fatty acids+Diglycerides

Diglycerides Fatty acids+Monoglyceride

Monoglyceride Fatty acids+Glycerol

4.DIGESTION OF CHOLESTEROL& PHOSPHOLIPIDS

In Small intestine-

The free cholesterol & phospholipid molecules converted into fatty acids & glycerol in the presence of bile salts.

Cholesterol Fatty acid+GlycerolPhospholipids Fatty acid+Glycerol

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