Digestion

Digestion- chemical and mechanical breakdown of large insoluable molecules into smaller soluable molecules which can be absorbed in the blood.

Food must be broken down into its building blocks before absorption.

Enzymes speed up digestion; they are biological catalysts.

Mechanical digestion is the physical breakdown of food in the oral cavity when we chew.

The food that we chew is mixed with saliva and is no longer called food but a bolus.

The bolus is moved through the gullet (oesophagus) through peristalsis.

Perstalsis is the movement of food through the gullet by the co-ordination of the circular and longitudinal muscles.

When the circular muscle contracts and the longitudinal relax, the gut is narrowedand when the longitudinal muscles contract and the circular relax, the gut is widened.