Reactive hyperemia occurs under what circumstance?

• A. Decreased blood flow during activity
• B. No change
• C. Reactive hyperemia occurs after occlusion is released.
• D. Flow remains constant after occlusion

Answer: (C)

Reactive hyperemia is the transient surge of blood flow that occurs to a tissue after a period of restricted blood supply is removed. When blood flow is blocked, the tissue becomes ischemic and metabolites such as adenosine, CO2, H+, and potassium build up, dilating the local arterioles. Once the occlusion is released, those vessels remain dilated and the increased demand to repay the oxygen debt causes a temporary flow spike that exceeds baseline. This is why the correct idea is that reactive hyperemia happens after the occlusion ends. It’s not about decreased flow during activity, no change, or flow staying constant after occlusion.