Level Up Your Knowledge with Anatomy & Physiology II 2026 Milestone 1 Practice Blast!

When tissues sense low oxygen, local chemical signals cause small arteries and arterioles to dilate. This vasodilation lowers peripheral vascular resistance because there are fewer constricted vessels for the blood to push through. Blood pressure depends on cardiac output times systemic vascular resistance, so if resistance falls and the heart doesn’t immediately increase its output enough to compensate, mean arterial pressure tends to drop. So the healthy, immediate response to hypoxia is decreased resistance and, often, decreased blood pressure.