4.2.1 Body Systems⭐人体系统

The body's circulatory system includes the heart and blood vessels.

The heart pumps blood to all parts of the body through a network of arteries and veins.

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 body's control system.

It controls your muscles and organs, including your circulatory and digestive system.

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, the immune system attacks it.

The blood vessels that carry oxygen-rich blood from the heart are called arteries.

The digestive system is where food is broken down and absorbed into the body.