Peristalsis is the muscular action of the digestive system. It occurs in the oesophagus and the intestine.
contraction
Area of relaxation
Food bolus
Area of contraction
Area of relaxation
Peristalsis Further Investigation
Learn more about peristalsis by watching the following videos on YouTube: ‘Through the Esophagus [US spelling of oesophagus] The Function of Peristalsis’ (1:41)
‘3D Medical Animation – Peristalsis in Large Intestine /Bowel’ (0:33)
The stomach
The stomach is a pouch-shaped bag with thick, muscular walls. It is situated in the top left-hand side of the abdomen under the diaphragm. It is similar to a mixing tank that churns the food into a liquid called chyme.
• The stomach lining contains cells which produce a liquid called gastric juice. The gastric juice contains the enzyme pepsin and an acid called hydrochloric acid, which pepsin needs to work effectively. This acid also kills most of the bacteria present in food.
• Fat melts because of the heat in the stomach, making the digestion of fat easier. The rhythmic churning of the stomach mixes the food with the gastric juice.
• Food usually stays in the stomach for one to four hours, but liquids may pass through in a few minutes.
Discovery Learning
In the stomach the enzyme pepsin mixes with hydrochloric acid. Can you find out what this enzyme does to protein in the stomach?
49 The stomach
Muscular walls
Discovery Learning Have you ever heard of ‘heartburn’? Did you know that it has nothing to do with your heart? Find out what heartburn is and its connection to digestion. Share your findings with the class.
