Cardiac output increases as a result of increases in stroke volume and heart rate. Which statement best describes this change?

Cardiac output increases as a result of increases in stroke volume and heart rate. Which statement best describes this change?

• A. Decreases
• B. Stays the same
• C. Increases
• D. Fluctuates

Answer: (C)

Cardiac output is the amount of blood the heart pumps each minute, calculated as heart rate multiplied by stroke volume. If both heart rate and stroke volume increase, the product becomes larger, so cardiac output rises. For example, resting values around 70 bpm and 70 mL per beat give about 4.9 L/min, while during activity a higher rate and larger stroke volume can push that toward 15 L/min. The other options would require one or both factors to decrease or stay the same, which isn’t the case when both rise. This increase helps supply more oxygen and nutrients to working muscles.

Cardiac output is the amount of blood the heart pumps each minute, calculated as heart rate multiplied by stroke volume. If both heart rate and stroke volume increase, the product becomes larger, so cardiac output rises. For example, resting values around 70 bpm and 70 mL per beat give about 4.9 L/min, while during activity a higher rate and larger stroke volume can push that toward 15 L/min. The other options would require one or both factors to decrease or stay the same, which isn’t the case when both rise. This increase helps supply more oxygen and nutrients to working muscles.