Both atria simultaneously pump blood into the ventricles. The ventricles then pump the blood to the lungs and the rest of the body. The number of times that the heart beats in a minute. A normal heart rate increases and decreases, depending on how strenuous one's activity level is. One's heart rate when sleeping is typically lower than when walking or running.
Emotional changes can also cause one's heart rate to increase.
These valves open to ensure that blood flows into the heart chambers as needed, and they close to ensure that blood does not flow back into the heart after it has been pumped out to the lungs and body. The sound made each time the heart muscles contract to pump blood into the lungs and throughout the body. A heartbeat consists of the contraction of the atria, quickly followed by the contraction of the ventricles. A vessel inside the chest wall that is commonly used to create an alternative pathway for blood to reach the heart muscle. Not receiving the needed blood flow.