Biological Paradox

man standing on head

Why Don’t Your Feet Become Red With Blood?

I always like to illustrate biology principles with simple concrete examples.

The answer I got about the flow of blood in the body was not one I was ready for.

After my lecture on blood flow, the class was posed this simple question:

“If I were to stand on my head, my face would become red because the blood would flow to my head.

Yet if stand up normally my feet remain their normal color.”

Who can explain that paradox?

A student casually answered, “That happens because your feet are not empty.”