The respiratory system is oxygen inhaled into the body and oxygen exhaled from the body. The oxygen is carried throughout all the body systems by blood through the blood vessels. The blood is then pumped by the heart. When a person is resting the blood pumps 5 liters of blood, when the person is exercising the heart pumps 7 times the amount of blood. The amount of air you breathe depends on how active you are. When …showed first 75 words of 256 total…

…showed last 75 words of 256 total…produce little energy. This can lead up to some problems though; your body can build up a chemical called lactic acid and can make your muscles ache. Athletes can train so that their lungs and muscles can become more efficient and it will take longer for lactic acid to build up in their bodies. People with diseases with their lungs cannot provide enough oxygen for their muscles so they cannot even walk a long distance.