An astronaut experiences prolonged microgravity; which effect dominates on returning to Earth due to thermoregulation and cardiovascular system interaction?

💡 Explanation

Microgravity exposure decreases blood volume; upon return to Earth, the cardiovascular system struggles to maintain blood pressure against gravity. This is due to impaired baroreceptor sensitivity combined with reduced blood volume affecting the autonomic thermoregulation, therefore orthostatic hypotension is likely, rather than increased bone density or enhanced reflex sensitivity.

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