This post is all about us! Or rather, it’s about the organ that allows us to do all the things we love to do. That’s right. The heart.
The heart is probably your most important organ. It pumps blood throughout your entire body which provides the rest of your organs with oxygen and nutrients that are necessary for them to function. Blood also carries away waste from those organs such as carbon dioxide (which then is transported to the lungs to be exhaled).
The heart works a lot like a sponge. There are special cells in the heart called pacemaker cells. These cells essentially send an electric jolt to the heart muscles that cause it to contract and wring the blood inside it out into the aortic valve, which leads to the aorta. The aorta is the largest artery in our body and is the entry way for blood to enter the rest of our veins.
After the heart is wrung out, it relaxes and the cells along the wall of the heart expand. This also relaxes the coronary vessels that rest on the outside of the heart. Once the muscle cells on the heart are relaxed, blood that was just ejected from the heart drips from the coronary vessels back into the heart to feed the muscle cells, which allows the heart to keep pumping. “Imagine clenching your fist sixty to seventy times per minute for your entire life, which is essentially what your heart does – without ever becoming exhausted” (Roizen and Oz. You: The Owners Manual. 33).
The heart is made up of four chambers. There are two atrium (think like an atrium in a house) and two ventricals. After blood has been circulated around the body, the oxygen that was in it has been used up by the various organs and muscles it visited. The blood is now “dirty” (or deoxygenated) and is circled back around to the heart. It is then returned to the right atrium which sends it into the right ventricle via the tricuspid valve. The right ventricle then send the “dirty” blood to the lungs via the pulmonary valve (the function of the valves is to keep blood from backtracking. If dirty and clean blood mixed, it would be much less effective at keeping our body working properly. The “heartbeat” that we hear is actually the valves slamming shut).
Once in the lungs, the blood takes the carbon dioxide which was given back to it by all the other organs and muscles and sends it out of the body (that’s why when we exhale, it is carbon dioxide that comes out). It then is infused with the oxygen that we just inhaled and sent back to the heart through the pulmonary vein and into the left atrium. The blood is then sent through the mitral valve into the left ventricle where it is squeezed back into the rest of the body via the aortic valve and the whole process starts over again.
Roizen, Michael F., and Mehmet Oz. You: The Owner’s Manual. (New York: Collins, 2005), 32-51.
Wikipedia. “Blood.” Accessed May 4, 2013. http://en.wikipedia.org/wiki/Blood
Wikipedia. “Human heart.” Accessed May 4, 2013. http://en.wikipedia.org/wiki/Human_heart