Respiratory and Circulatory Systems

is a system in the body that deals with breathing. When we breathe we take in oxygen that we need and removes carbon dioxide that we don't need.

Air enters the body through your mouth or nose. It then travels down your trachea (windpipe) which divides into two tubes called bronchi. These tubes carry air into each lung. The diaphragm is a muscle that controls breathing. This muscle becomes flat to let air into the lungs, and relaxes to push air out of the lungs.

Blood carries things like oxygen and nutrients to each cell in the body. The heart pumps blood through the body through a system of tubes called blood vessels.

Arteries are a type of blood vessel that carries oxygen-rich blood away from the heart. Veins are another type of blood vessel which carries oxygen-poor blood back to the heart.