Labels:bulletin board | hakham | sky OCR: HEART RATE OUR HEART pumps blood around your body supplying t with oxygen for energy The rate at which your heart beats Is adjusted automatically by the autonomic nervous system. During exercise, your demand for energy increases and the sympathetic nervous system causes your heart to beat faster. When you stop exercising, the demand for energy Is reduced and the parasympathetic system slows your heart down. At rest the two systems work together to maintain a steady heart rate Cross section of the heart Cardiac muscle Rate of heartbeat supply parasym ipathetic
(Dorling Kindersley).iso/smbm/auto/auto001p.png){kind=small}