How does peristalsis let you swallow upside down?
See, now that right there is the reason I love Cecil! 
I’m surprised he didn’t mention that are actually pumps (called, naturally, peristaltic pumps) which use this exact principle. They’re used frequently in medicine for pumping blood through equipment like dialysis machines, since impeller-type pumps capable of generating sufficient pressure can damage blood cells through high-speed impact.