Since the heart is a muscle, it relies on the oxygen and nutrients contained in blood. This blood is supplied by arteries on the exterior of the heart -- when these arteries are blocked, a heart attack results. Listen to find out in this podcast from HowStuffWorks.com.
Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

BrainStuff Classics: Why Are Some Americans Cancelling Columbus Day?
07:16

American Versus British English: What Are Biscuits, Muffins, and Pudding?
09:51

How Do Sunspots Work?
14:22