medium · MCAT bio-biochem
During heavy exercise, a cyclist's heart rate increases to 150 bpm.
How does this change the duration of the cardiac cycle, and which phase is most significantly shortened?
- Cycle duration increases; systole (contraction) is shortened to increase speed.
- Cycle duration decreases; isovolumetric contraction is the primary phase shortened.
- The duration of all phases is reduced proportionally by 50%.
- Cycle duration decreases; diastole (filling) is shortened more than systole.
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