How does the heart respond to increased physical activity?

• A. It decreases heart rate and stroke volume
• B. It pumps less blood to the muscles
• C. It increases heart rate and stroke volume
• D. It generates more oxygen in the lungs

Answer: (C)

During increased physical activity, the body demands more oxygen and nutrients to support the functioning of muscles. The heart responds to this demand by increasing both the heart rate and stroke volume.

The heart rate, which is the number of times the heart beats per minute, escalates to circulate blood more rapidly throughout the body. This ensures that more oxygen-rich blood reaches the muscles and other tissues that are working hard during physical exertion. Concurrently, stroke volume, which is the amount of blood ejected by the heart with each beat, also rises in response to this increased need. A higher stroke volume means that with each contraction, the heart pumps more blood, thereby delivering even more oxygen and nutrients to the working muscles.

The combined increase in heart rate and stroke volume allows the cardiovascular system to effectively meet the heightened metabolic demands of the body during physical activity. This is a vital mechanism that supports endurance and performance during exercise.