We have known for decades that genes play a part in the brain's function, but research also shows a baby's environment plays just as large a role. Brought to you by the Discovery Channel.
WHAT'S INSIDE: HUMAN BODY
- Body Parts
- Body Systems
Why don't you have two hearts? Here's a hint: It's the same reason why you have one liver, but two eyes. Would a second heart help you live better?
The heart is a vital organ that basically serves as a pump. Learn about heart chambers and valves, blood flow, the heart's electrical system and blood supply. Read more about how this amazing organ works.