HUMAN NUTRITION

Detailed explanation-1: -Digestion begins immediately in the oral cavity with both mechanical and chemical digestion. Mechanical digestion in the oral cavity consists of grinding of food into smaller pieces by the teeth, a process called mastication.

Detailed explanation-2: -The Mouth The mouth breaks down food by both mechanical and chemical digestion.

Detailed explanation-3: -Saliva secreted by salivary glands aids the mechanical and chemical process of digestion. Saliva is about 99% water and not only moistens food but cleanses the mouth, dissolves food chemicals so they can be tasted, and contains enzymes that start the chemical breakdown of starchy foods.

Detailed explanation-4: -Mechanical Digestion The large pieces of food that are ingested have to be broken into smaller particles that can be acted upon by various enzymes. This is mechanical digestion, which begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach.

Detailed explanation-5: -Peristalsis. Peristalsis moves food through the digestive tract with alternating waves of muscle contraction and relaxation. Digestion includes both mechanical and chemical processes.