<P> The heart pumps blood with a rhythm determined by a group of pacemaking cells in the sinoatrial node . These generate a current that causes contraction of the heart , traveling through the atrioventricular node and along the conduction system of the heart . The heart receives blood low in oxygen from the systemic circulation , which enters the right atrium from the superior and inferior venae cavae and passes to the right ventricle . From here it is pumped into the pulmonary circulation , through the lungs where it receives oxygen and gives off carbon dioxide . Oxygenated blood then returns to the left atrium , passes through the left ventricle and is pumped out through the aorta to the systemic circulation − where the oxygen is used and metabolized to carbon dioxide . The heart beats at a resting rate close to 72 beats per minute . Exercise temporarily increases the rate , but lowers resting heart rate in the long term , and is good for heart health . </P>
<P> The heart pumps blood with a rhythm determined by a group of pacemaking cells in the sinoatrial node . These generate a current that causes contraction of the heart , traveling through the atrioventricular node and along the conduction system of the heart . The heart receives blood low in oxygen from the systemic circulation , which enters the right atrium from the superior and inferior venae cavae and passes to the right ventricle . From here it is pumped into the pulmonary circulation , through the lungs where it receives oxygen and gives off carbon dioxide . Oxygenated blood then returns to the left atrium , passes through the left ventricle and is pumped out through the aorta to the systemic circulation − where the oxygen is used and metabolized to carbon dioxide . The heart beats at a resting rate close to 72 beats per minute . Exercise temporarily increases the rate , but lowers resting heart rate in the long term , and is good for heart health . </P>
the heart chamber that acts as an entry for blood
the heart chamber that acts as an entry for blood
the right atrium
the right atrium