BodyQuest Tour: Stop 3
Lungs 
Your body is composed of many systems. Besides the nervous system, two of the other biggest systems are the Circulatory System, and the Respiratory System. 

 
Circulatory System & Respiratory System
Your circulatory system is the system of circulating blood that flows around your body. It is a vital body system, because you would not be alive without blood! 

It is composed of the heart, veins, and arteries. The veins carry used blood towards the heart and the arteries carry fresh blood away from the heart. 

The heart is like a pump that contracts and expands to force blood around your body. Your circulatory system links in with your respiratory system in the lungs. In the lungs, oxygen from air is mixed into your blood stream. 
Your respiratory system is composed of the mouth and nose, the trachea, and the lungs. Air is taken in through the mouth and the nose, where it is filtered and warmed before going into your lungs. Your lungs then expand and oxygen is taken in from the air. The oxygen poor air is then breathed out, or exhaled. The whole process then starts again. 
The two systems work very closely together to transfer oxygen from your lungs into your blood stream. 
 

 

  
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