UNIT OVERVIEW

Your body needs oxygen to stay alive. Every cell in your body uses oxygen to release energy from food. This process also makes carbon dioxide, which your body must remove.

Two body systems work together like a delivery team:

• The respiratory system brings oxygen into your body from the air
• The circulatory system carries that oxygen to every cell and brings carbon dioxide back

In this unit, you will learn:

• The parts of the respiratory system and what each part does
• How breathing works and how gases are exchanged
• The structure of the heart, blood vessels, and blood
• How the two systems work together to keep you alive
• Common health problems and how to prevent them

By the end, you will understand:

• Why your breathing speeds up when you run or climb stairs
• Why smoking is so harmful to your lungs
• Why regular exercise makes your heart stronger

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