During exercise, which mechanism primarily increases myocardial oxygen delivery?

During exercise, which mechanism primarily increases myocardial oxygen delivery?

• A. Heart rate and contractility rise; systemic arterioles dilate to increase coronary flow; coronary vessels near maximal dilation allow increased blood supply.
• B. Heart rate decreases and coronary vessels constrict.
• C. Coronary vessels constrict to limit flow.
• D. Blood pressure falls causing reduced flow.

Answer: (A)

During exercise, the heart needs more oxygen, so the body increases coronary blood flow to meet that demand. The rise in heart rate and contractility boosts myocardial activity and oxygen consumption, signaling the coronary vessels to dilate. This vasodilation of the coronary arterioles, driven by the heart’s increased metabolic needs, greatly increases blood flow to the myocardium. At the same time, systemic arterioles can relax, reducing afterload and helping raise overall perfusion pressure, which further supports greater coronary flow. The coronary vessels are already primed to dilate and can do so further to deliver the extra oxygen-rich blood the exercising heart requires.

During exercise, the heart needs more oxygen, so the body increases coronary blood flow to meet that demand. The rise in heart rate and contractility boosts myocardial activity and oxygen consumption, signaling the coronary vessels to dilate. This vasodilation of the coronary arterioles, driven by the heart’s increased metabolic needs, greatly increases blood flow to the myocardium. At the same time, systemic arterioles can relax, reducing afterload and helping raise overall perfusion pressure, which further supports greater coronary flow. The coronary vessels are already primed to dilate and can do so further to deliver the extra oxygen-rich blood the exercising heart requires.