As humans, we’ve always related the heart to feelings and emotions. History added: “Since the human heart has long been ...

But how much do you really know about your heart and how it ... Capillaries, on the other hand, are so small that it takes ten of them to equal the thickness of a human hair.

Originally appeared on the NOVA Web site Cut to the Heart ... Capillaries, on the other hand, are so small that it takes ten of them to equal the thickness of a human hair. Your body has about ...