Cardiac Output is the product of heart rate and stroke volume. It measures the amount of blood pumped by heart, specifically left ventricle in one minute. Left ventricle is chosen to calculate it because it is the one which pumps blood to the entire body.
While calculating cardiac output two components are taken. Heart rate is the measure of number of times heart beats per minute. It increases with increase in activity intensity as muscles require more energy. Normal resting heart rate range for an adult is 60-100 bpm. Stroke volume is the amount of blood pumped by left ventricle during each heart beat. It is estimated by other factors like blood pressure. If either heart rate or stroke volume or both increase, cardiac output will also increase.
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because the sodium channels have a refractory period following activation, during which they cannot open again and it ensures that the action potential is propagated in a specific direction along the axon.
