6 Interesting Facts About Your Heart You May Not Know

Earlier I wrote a post describing the basic anatomy of the heart. In this post, I’d like to talk about some other interesting facts about your heart. This is all in an effort to help us all become heart experts. That said, here are 6 more interesting facts about your heart.

Heart facts

Pericardium

Your heart is a muscle about the size of your fist. Did you know that it is also wrapped up in a sac? It’s true! This sac is called the pericardium. The main function of this sac is to keep the heart safe from invading bacteria and viruses, although it also helps to aid in the functionality of the heart.^1-3

Sinoatrial node (SA node)

Your heart makes its own electrical impulse and it is this impulse that causes your heart to beat for the duration of your life. The SA node is a small collection of cells inside the wall of the right atrium. The electrical impulse travels to both atria causing them to contract. It then travels to both ventricles causing them to contract. Your SA node is often referred to as your natural pacemaker because it is what normally determines your heart rate. A normal heart rate set by your SA node is 60-100 beats per minute.^1,4

Atrioventricular node (AV node)

The AV node is an area of heart tissue between the atria and the ventricles that receives the electrical impulse after it travels through the atria. It causes this impulse to pause. This pause is important because it allows time for blood to flow from the atria to the ventricles. The AV node then allows the electrical impulse to travel to the ventricles. They contract to send blood to your lungs and all the tissues of your body. Some people refer to the AV node as your second natural pacemaker.^1,5

Ectopic pacemakers (automaticity foci)

As noted above, your SA node is your natural pacemaker. But what happens if it fails to trigger an impulse to start a heartbeat? When this happens, there are other cells in your heart that can act as pacemakers. They are referred to as ectopic pacemakers. Areas of your heart that can become pacemakers are called automaticity foci. If an area in your atria becomes your pacemaker, your inherent heart rate will be 60-80 BPM. If an area of your ventricles becomes your pacemaker, your inherent heart rate will be 20-40 BPM.^1,5

Overdrive suppression

There is another thing that can happen to cause an automaticity foci to become a pacemaker. Let's say that areas of the atria become excitable and they start generating beats faster than the SA node would. In this case, the faster pacemaker suppresses the activity of the slower pacemaker. Here, the atria foci suppress the SA node. This is what causes an abnormal heartbeat called atrial fibrillation. This is also what causes an abnormal heartbeat called supraventricular tachycardia.⁵

Coronary arteries

Your heart is a muscle and muscle is tissue. Like all the tissues of your body, heart tissue requires nutrients and oxygen. Feeding these to your heart is a series of arteries called coronary arteries. These arteries carry freshly oxygenated blood to all the different areas of your heart.^1-2

The heart is such a fascinating organ and these 6 facts are just the beginning. This is all in our effort to become heart-smart. Please share in the comments below if you have any interesting heart facts to share.