1.2
Human organ systems
The nervous system
brain
The nervous system helps different parts of the body to communicate with one another. Signals travel along nerves from the brain and spinal cord to all the other body organs.
spinal cord nerves
Sense organs are also part of the nervous system. For example, your eyes sense light. Signals travel from your eyes to your brain.
The respiratory system The respiratory system is where oxygen enters your body and carbon dioxide leaves it. All of your cells need oxygen, so that they can respire. This is how they get their energy. When cells respire, they make carbon dioxide, which is a waste product. Air moves down a series of tubes, until it is deep inside the lungs. This is where oxygen moves into your blood. Carbon dioxide moves out of the blood and into the lungs. The air containing this carbon dioxide moves out of the lungs when you breathe out.
trachea (windpipe) lung bronchus ribs diaphragm
Questions
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1 Plants and humans as organisms
9