Introduction

a) Catabolism : Process by which nutrients are broken into small pieces.

b) Anabolism : Reaction by which biomolecules are synthesized from simpler components.

Digestion of carbohydrate

• Digestion of starch begins in mouth and continues in the duodenum.
• Saliva and pancreatic juice contains α-amylase which attack α1à4 glycosyl bond.
• Most of the hydrolysis of starch occurs in small intestine.
• Maltose is formed during the hydrolysis of starch.

Fate of absorbed glucose

• Glucose is absorbed from gut within an hour.
• Absorbed glucose is transported into the tissue and the glucose concentration quickly returns to its basal value.
• Liver then convert glucose to glycogen or fatty acid.
• The uptake and utilization of glucose is stimulated by insulin.

a) In muscle, insulin stimulates glycogen deposition by activation of glycogen synthetase and inhibition of phosphorylase.

b) Conversion of glucose to fatty acids is stimulated through effects on pyruvate dehydrogenase and acetyl CoA carboxylase.