Your heart can beat over 200 times per minute during maximal exercise, depending on your age, yet every beat is a succinct event made up of many steps with every one of those beats controlled by the electrical system of the heart. While that’s incredible in and of itself, the real story is one of the most amazing features of your heart called autorhythmicity.

Your heart has a special area in one chamber that stimulates it to beat. It’s called the sino-atrial node (SA node) or the pacemaker. Think of that as the command center: it takes information coming from your body and sets the pace of your heart rate.

What you might not know is that some cells of the heart can stimulate themselves to beat. If something goes wrong with the electrical system for some reason, your heart can go right on beating because of the muscle make-up we talked about in Saturday’s Memo on syncytium. It lends itself to this autorhythmic feature. Think of it as the ultimate fail-safe system—makes you sleep a little easier, doesn’t it?

One more cool feature I’ll talk about on Saturday.

What are you prepared to do today?

        Dr. Chet