List and describe two internal influences and two external influences on physical activity

The lungs take in oxygen and pass it into the bloodstream, which oxygenates the muscles, allowing them to move. The heart pumps the oxygenated blood through the body, [ feeding the lungs so they can breathe and get more oxygen; feeding the brain so that you know how to move and see and breathe, enabling activity. The GI system allows us to eat nutritious foods,