If you're seeing this message, it means we're having trouble loading external resources for Khan Academy.
If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.
Fri, 02 Nov 2012 18:29:00
Rishi Desai, M.D. has released the first videos in a new series looking at how the pressure created by your heartbeat moves blood through your heart.