PATHOLOGY

Detailed explanation-1: -During exercise, your body may need three or four times your normal cardiac output, because your muscles need more oxygen when you exert yourself. During exercise, your heart typically beats faster so that more blood gets out to your body.

Detailed explanation-2: -Cardiac output during exercise increases greatly owing to the relatively high heart rates that are achieved during exercise. Heart rate increases proportionately with workload until heart rates close to maximal are attained.

Detailed explanation-3: -When you exercise, your body releases chemicals such as dopamine (pronounced doh-pa-meen) and endorphins (en-door-fins) in your brain that make you feel happy. Not only is your brain dumping out feel-good chemicals, but exercise also helps your brain get rid of chemicals that make you feel stressed and anxious.

Detailed explanation-4: -The lungs bring oxygen into the body, to provide energy, and remove carbon dioxide, the waste product created when you produce energy. The heart pumps the oxygen to the muscles that are doing the exercise. When you exercise and your muscles work harder, your body uses more oxygen and produces more carbon dioxide.