Robert, body=machine is only an analogy, and a very inexact one. If you want to see how the body works, look at information about the body, not about air compressors and plumbing. Look at information coming from the professionals who could literally cut your heart out and put a new one in, without killing you. I put a couple of informative links into the post above.

[Note: I see I'd gibbled the quote marks in that post, so it looked like most of it was a quote from you. I've fixed it. Please take another look.]