Slide 1: Digestion and Absorption Slide 2: Digestion is the process where complex organic molecules of food stuffs are converted to smaller molecules which are easily absorbed by GIT Slide 3: Gastro Intestinal tract Mouth - Saliva
Stomach - Hcl, Gastric enzymes
Pancrease - NaHCo3 and many enzymes
Liver - Bile acids
Small Intestine - Final digestion and Absorption Slide 4: Saliva - Secreted by Salivary glands Contains - 99.5% water
- Salivary enzymes ( Salivary amylase,
Lingual Lipase) Slide 5: Gastric Juice - 97 – 99% water
- 0.2 – 0.5 % Hcl with a pH - 1
- Mucin, Inorganic salts.
- Digestive enzymes
(Rennin, Pepsin, Lipase) Slide 7: Bile - Liver produces Bile
Neutralization of acid
Excretion Slide 8: Pancreatic Juice - non viscid watery fluid.
contains - Proteins, Organic & Inorganic compounds
- Many enzymes
Trypsin, Chymotrypsin, Elastase, Carboxypeptidase, Amylase,
Lipase, Phospholipases, Cholesterolesterases, Ribonuclease Slide 9: Intestinal Juice Secreted by the glands of Brunner & Luberkerhin
- - glucosidases
- Phospholipases Slide 10: Digestion of Carbohydrates The major Dietary carbohydrates are
Sucrose Slide 11: Digestion of carbohydrates in mouth Salivary - amylase (ptyalin) acts on
1,4 glycosidic bonds randomly and the products
maltose. No carbohydrate Digestion in stomach Slide 12: Digestion in Small Intestine
The acidic contents are neutralized by NaHCo3
present in PancreaticJuice.
Pancreatic amylase acts on starch and cleaves 1,4
glycoside bonds and the resultant products are
Disaccharides and Oligosaccharides.
Oligosaccharidases, Disaccharidases, Sucrase & Lactase
finally digest and the products to monosaccharides. Slide 13: Absorption of monosaccharides
The end products of Carbohydrate digestion are
Absorption of carbohydrates mostly takes place in Duodenum and upper jejunum. MECHANISM OF ABSORPTION : MECHANISM OF ABSORPTION Glucose is transported into the intestinal mucosal cells by carrier mediated and energy requiring process.
Phlorizin blocks the sodium dependent transport of glucose. Abnormalities of carbohydrate digestion. : Abnormalities of carbohydrate digestion. Lactose intolerance - lactase deficiency
lactose accumulates in the gut,it is acted upon by bacteria to produce organic acids, and these acids take up water from intestinal cells by osmotic effect and produce diarrhea.
Benedicts test is +ve for stool samples.
Treatment: restriction of milk and milk products. Slide 16: Digestion and Absorption of PROTEINS
Daily Protein load for digestion is around 100 – 200 gms
- Dietary Protein - 50 – 100 gms/day
-Endogenous Protein - 30 – 100 gms/day
Proteins are degraded by Hydrolases, called as Peptidases
Endopeptidases – which attack internal peptides and release peptide fragments.
Exopeptidases - which attack peptide bonds of terminal amino acids
Amino peptidases Slide 17: Proteins are not digested in Mouth
Digestion in Stomach
HCL has 2 functions
It denatures Protein
It kill microorganisms
Pepsin: It is produced in inactive form pepsinogen
It is converted to pepsin by Hcl &
Pepsin molecules ( Auto catalysis)
Pepsin is acid stable – active at very low pH i.e., 2.0 Rennin ( Chymosin) : Rennin ( Chymosin) It is found in the stomach of Infants & children
It converts casein Calcium Paracaseinate
It is involved in curdling of milk
Rennin is absent in adults. Pancreatic Digestion of Proteins : Pancreatic Digestion of Proteins NaHCo3
Pancreatic Juice Trypsin
Secretion of Pancreatic is stimulated by Cholecystokinin and Pancreozymin
All the Pancreatic enzymes are active at neutral pH.
All these enzymes are secreted as inactive forms, these are converted to active form by ‘Enteropeptidase’ (Enterokinase) Slide 20: Intestinal Digestion of Proteins
Complete digestion of proteins is brought by enzymes present in Intestinal Juice
Dipeptidases Slide 21: Absorption of Amino acids
Mainly in small intestine
Energy requiring process .
Five different transporters are present
1. Neutral Amino Acid
2. Basic Amino Acid
3 . Acidic Amino Acid
4. Iminoacids and Glycine 5. - Amino acid