How does hypohydration affect stroke volume, cardiac output, and heart rate?

Hypohydration, or dehydration, significantly impacts cardiovascular performance by affecting stroke volume, cardiac output, and heart rate. When the body is hypohydrated, the total blood volume decreases, which directly reduces stroke volume—the amount of blood pumped by the heart with each beat.

As stroke volume decreases, the heart compensates by increasing heart rate. This compensatory mechanism helps to maintain cardiac output, which is the product of stroke volume and heart rate. However, even though the heart rate increases, the reduced stroke volume generally leads to a lower overall cardiac output.

This physiological response reflects the body's attempt to maintain adequate perfusion and oxygen delivery under dehydrated conditions, but ultimately it results in a less effective cardiovascular performance during exercise or physical activity. Thus, the correct answer accurately describes the effects of hypohydration as reducing stroke volume, reducing cardiac output, and increasing heart rate to compensate for the decreased blood volume.