Upon vigorous exercise, your heart rate increases to 200 beats per minute to supply sufficient oxygen to muscles. Which is responsible for this regulation of the heart rate? A. Semilunar valves

B. Sinoatrial node

C. Aorta

I think the correct answer from the choices listed above is option B. The one that is responsible for the regulation of the heart rate is the sinoatrial node. It is the heart's peacemaker. It is a specialized bundle of neurons which controls the cardiac function. Hope this answers the question.