Final answer:
Cardiac output is determined by multiplying heart rate by stroke volume. Changes in heart rate or stroke volume can significantly affect the CO, with factors such as exercise resulting in a considerable increase in CO.
Step-by-step explanation:
Cardiac output (CO) is the volume of blood that the heart pumps in one minute. It is calculated by multiplying the stroke volume (SV), which is the amount of blood pumped by each ventricle per beat, by the heart rate (HR), which is the number of heartbeats per minute. The equation for this calculation is CO = HR × SV. The stroke volume can be influenced by factors like preload, contractility, and afterload, while the heart rate can be affected by autonomic innervation, endocrine control, and various environmental factors such as electrolytes, metabolic products, and temperature. During exercise, both HR and SV can increase, leading to a higher CO, which promotes increased blood flow and blood pressure.
For instance, in healthy young individuals during exercise, the heart rate (HR) may increase to 150 beats per minute (bpm), and stroke volume (SV) can increase from 70 to approximately 130 mL due to a stronger contraction. This can result in an increase in cardiac output (CO) to approximately 19.5 liters per minute, which is about 4-5 times the resting rate. Top cardiovascular athletes can achieve even higher CO, elevating their resting CO by 7-8 times at peak performance.