Lub-dub, lub-dub, lub-dub, that's usually the sound of a happy heart. But what's responsible for that steady, comforting beat, and what if your heart doesn't sound like that?
WHAT'S INSIDE: HUMAN BODY
- Body Parts
- Body Systems
We all pass gas, but not all of us like to talk about it — or study it to figure out how quickly it travels out of the body.
Vestigial organs are like the contents of your junk drawer: an assortment of objects that once had a purpose or might come in handy. What can these evolutionary mementos tell us?