Thermal ultrasound stimulates which body system?

• A. Immune
• B. Nervous
• C. Endocrine
• D. Circulatory

Answer: (A)

Heating from ultrasound raises tissue temperature, triggering vasodilation and increased blood flow to the treated area. This circulatory response is the primary way the body is affected by the thermal effect, improving perfusion, nutrient delivery, and waste removal to support tissue healing. There can also be changes in nerve conduction and pain perception (nervous system effects) and indirect effects on immune function via better circulation, but the direct and most prominent systemic change is to the circulatory system. Endocrine effects are not a primary outcome of thermal ultrasound. Therefore, the circulatory system is the system most directly stimulated.