Basic Heart Anatomy- The Four Chambers

Hello everyone, welcome back to the student cardiologist. Today's topic is going to be on the anatomy of our heart. Before we begin, I want you to subscribe to my blog, which is located at the top right hand side of this web page. This blog can be served as a great reliable resource for you in understanding the materials that you learn in classroom or in your medically related training. Your subscription will also greatly motivate me to write more lecture materials to help you in whatever you do, either in school, work, or just for personal interest. Thank you!

Let's get started.

Our heart is a very sophisticated organ, in a biochemistry level as well as on the mechanical level. We all know that our heart is used for pumping blood and nutrients to the rest of our body, and to keep us alive.  But not many know that there are so many small components and chemical reactions happening to make this organ to have a consistent but controllable heartbeat. For example, the diagram below is just one signal processing pathway in our heart for cardiac muscle contraction, and it is amazing that it takes that much work and chemical and proteins to make our heart contracts at a regular or modifiable rate!!!

Like many other animals (Not all), our heart is consisted of 4 chambers, with  2 chambers on each side. There are a lot of blood vessels of different sizes attaching to each chamber like the aorta. These 4 chambers are called the atriums and ventricles. There are 1 atrium and 1 ventricle on each side of the heart, makes 2 atriums, 2 ventricles and 4 chambers in total. Atrium is a relatively small chamber compared to the ventricle  found within the heart. Their main functions were to receive blood from the veins, and pump additional blood from the atrium into the ventricles. This pumping action will therefore push the blood into the ventricle allow more blood to be delivered to different places of our body.

Ventricles, on the other hand, are used to pump blood either to the lung, so that the blood can be oxygenated, or to the rest of our body. The ventricles are a lot stronger than the atriums because they have to provide blood to a greater area. Imagine the ventricle has to pump blood from your heart to your toes while atrium is only from the top of the heart to the bottom! Therefore, when observed, they have a thicker wall, which tells us that there are a lot more cardiac muscles compare to the atrium.

Fun fact: amphibians only have 3 chambers and fish only have 2!!

For naming conventions, anatomists name the side of the atrium and the ventricle regarding to the patient's side. So, our right is their left, therefore it is the left atrium and left ventricle on the right hand side of the diagram. Below is a cadaver picture of a heart, which looks very close to heart illustration above.

So what happen when our ventricle chambers are not working properly?

One common defects that we will enter into is call V-fib, or ventricular fibrillation. This is a serious condition in which our ventricle wall muscle (cardiac muscle) is not coordinated, which means that they do not contract at the same time. This therefore provides a weak contraction that is not sufficient to pump blood across the body, which may essentially lead to cell death in organs if waited for too long. When that happens, we need to use the electrical defibrillator to "jump-start" the heart again. These defibrillator are the pads that we see in many hospital shows like "Grey's anatomy", "House" or "ER".

How about fibrillation at the atriums?

Since atriums are only responsible for pushing additional blood into the ventricles, a defect at the atriums are not as deadly as V-fib. A-fib, or atrial fibrillation are often controlled by using drugs that can help to maintain the rhythm of the atriums, to reduce symptoms like shortness of breath and irregular heartbeat.

Next time, we will be more specifically talking about the vessels that are drained into each of those chambers and how they are connected through arteries and veins. Ultimately, these arteries and veins come together to form a close loop circuit, or the collateral circuits that allow blood to flow through all the organs and return back to the heart. 

I will see you next time! Don't forget to subscribe :)

Jeff