SLIDE NO.2

1. Physiology
Of
Digestion

8. Steps of Digestion

17. Human
Digestive
System

19. Salivary Glands and its functions
• Saliva contains two
major proteins
– Serous secretion
(ptyalin which is an
alpha amylase)
enzyme for digesting
starch
– Mucous secretion
(Mucin),
lubricating and
surface protective
purpose

22. Swalloing Reflex and esophageal peristalsis

27. Regulation of gastric acid
secretion is done by
Acetylcholine
Gastrin
Histamine

31. Pancreas

36. Liver and Gall bladder

37. Liver Functions
• Filtration and cleansing of blood
• Metabolism of carbohydrate, protein, fats, hormones,
foreign chemicals
– Storage of glycogen, oxidation of fatty acids, deamination of
amino acids, gluconeogenesis
• Formation of bile and blood substances used in
coagulation (coagulation factors)
• Storage of iron as ferritin, vitamins, ions etc
• Removes excess of drugs, hormones etc.

38. Liver Secretion and gall bladder emptying

39. Composition of bile:
bilirubin, cholesterol, lecithin,
electrolytes of plasma

41. General Principle of Digestion
• Mixing , lubrication of food with secretion of GI tract- uniform
homogenization
• Enzymes breaks down complex molecules into simpler molecules such
as oligimers , dimers, monomers etc
– All digestive enzymes act by hydrolysis
– GI tract enzymes are secreted as inactive precursors, activated when required
• Secretion of acid and bicarbonate from GI tract ensures optimal pH
for digestion
• Secretion of emulsifying agents helps in emulsifying dietary fat and
promote fat digestion
• Final digestion of oligomers and dimers occur at small intestinal
brush border resulting in release of monomers that are finally
absorbed.

49. Digestion and
absorption of
carbohydrates
in the GI tract

51. Digestion and
absorption of
proteins
in the GI tract

53. Digestion and
absorption of fats
in the GI tract

55. Absorption of nutrients
• Water is transported entirely by diffusion
• Sodium by active transport
• Glucose is transported by a sodium cotransport
mechanism (secondary active transport process)
• Peptides and amino acids bind to proteins and
transported, also by secondary active transport
process
• Fatty acids and monoglycerides directly diffusion to
epithelial cells.

56. Absorbing Colon –absorb water, electrolytes
Storage colon –storage feces

58. Control of Digestion