GCSE Biology: The Small Intestine

How the small intestine is adapted for absorbing and digesting food. A sphincter muscle is a small muscle along the alimentary canal. They can close and block off the stomach so no more food can enter. Sphincter muscles can be found at the entrance to the stomach, the exit from the stomach, the end of the small intestine and at the anus.

Mucus is secreted from the stomach by special cells which make mucus. There is a layer or mucus on the inside of the stomach to protect it from th e reactions.

Amylase is secreted in the mouth and the pancreas. It breaks down starch.

The epiglottis is a small flat that covers the opening of the trachea. It opens to let air in and closes when you swallow.

The walls of the stomach secrete hydrochloric acid to kill bacteria and create good conditions for pepsin to work in.

The duodenum, jejeunum and ileum make up the small intestine. In the duodenum bile and pancreatic juice are secreted.