1.21 How the Heart Works

Lets talk about how the heart works when it is healthy and normal so that we can understand better what happens during different heart diseases.

We can understand the heart by separating the anatomy and physiology into 4 main groups:

  • The heart muscle
  • The coronary arteries
  • The heart valves
  • The electrical conduction system

The Heart Muscle

The heart is basically one crazy complex muscle that has one simple job, pump and circulate blood throughout the body. Sounds easy, right? Well think about the more than 100,000 heartbeats each day and about 40,000,000 heartbeats you have each year that your heart has to perform. That’s a lot.

The heart does not look like what you see on Valentines day. It actually looks like this:

There are 4 chambers in the heart. The two on the top are called “atrium” and the two on the bottom are called “ventricles.” The most important chamber of the heart is called the “left ventricle”. The job of the left ventricle is to squeeze and pump blood to all your organs including your brain and your muscles. Anything that disrupts the heart’s ability to pump blood will cause problems as we will see.

The Coronary Arteries

The heart muscle needs a lot of oxygen and nutrients to get the energy to keep on contracting and pumping. The “coronary arteries” are the pipes that help deliver that blood directly to the heart muscle to keep it going. Here is a drawing of how they look:

Most people have 3 main coronary arteries, but there are some variations. The coronary arteries are where the cholesterol and calcium plaque can build up leading to problems as we will see.

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