Question

What is digestion? Explain the process of digestion in the mouth cavity and stomach. Add a note on peristalsis.

Answer 1

• Digestion can be defined as the process of breakdown of food into smaller and simpler substances which can be readily absorbed and assimilated by the body. It involves both mechanical and enzymatic breakdown of food.
  
• Digestion begins in the mouth. The food is ground up by the teeth and moistened with saliva to make it easy to swallow. Saliva also has a special chemical, called amylase, which starts breaking down carbohydrates into sugars. Once swallowed, muscular contractions of the esophagus massage the ball of food down into the stomach.
  
• The food passes through a sphincter into the stomach. Here it is mixed with gastric juices. The stomach is a muscular bag and it churns the food to help break it down mechanically as well as chemically. The food is then squeezed through a second sphincter into the first part of the small intestine, called the duodenum.
  
• Peristalsis is a series of muscle contractions and relaxations which occur along the course of the intestinal tract to push food and waste products through.