Question

What are the chemical and mechanical events occurring during digestion?

Answer 1

The chemical events include digestion of macromolecules like carbohydrates, fats and proteins. After digestion,these are absorbed at various sites throughout the GIT . Mainly absorption takes place in small intestine.

Digestion of carbohydrates starts from the mouth and continues till small intestine. Complex carbohydrate like starch are broken down into simple absorbable compounds like glucose by activity of various enzymes. Examples of enzymes are maltase, lactase , lingual lipase ,dextrinase etc.

Proteins are also digested into simpler compounds and absorbed. Complex polypeptides are broken down into amino acids by peptidases, proteases, dipeptidases etc.

Fats are mostly present as triglycerides. These are broken down into fatty acids and glycerol by the activity of lipase enzymes.

Mechanical events starts from mixing and breaking of food in mouth. The food is broken down into small pieces and mixed with saliva by mechanical action of tongue and teeth. The broken food particles are called bolus. This bolus moves down the GIT by the activity of esophagus called peristalsis. Movement of oesophagus in a pulsatile manner to move the food is called peristalsis. When food reaches the stomach, contractions in stomach starts.

Movements also occur in small and large intestine. These movements are essential for movement of food throughout the tract.