流利说 D77 2018-09-18 二
学习
Level4-Unit1-Part4*Learning-
- "Vocabulary-Body Systems"
The body circulatory system includes the heart and blood vessels. The heart pumps the bloods to all parts of body through a network of arteries（动脉） and vein.
The digestive system breaks down and absorbs food into the body. It supplies the energy that the body needs for growth and repair. After digestion, excess food is turned into waste and eliminated from the body.
The nervous system includes the brain, spinal cord and nerves. This is your bodies control system. It controls your muscles and organs included your circulatory and digestive system.
The nervous system regulates your heartbeat and digestion.
The respiratory system includes the nose and lungs. It brings air and oxygen into the body and removes carbon dioxide. The lungs are where oxygen enters the bloodstream and carbon dioxide is removed.
The immune system protects the body against infections and diseases. Sneezing and fever are examples of how the immune system works. If an infection invades the body and the immune system attacks it.
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