Medical Central: The Heart

Today's subject is something commonly known as the Heart. It is actually an organ. I've mentioned before that it has its own special muscle... cardiac muscle! But now let's explore the Heart a little more!

The Heart
The heart is primarily a big muscle, and a big pump. It pumps blood throughout our body, bringing food and oxygen to wherever it's needed. How does it do this? Like any other muscle, it contracts and relaxes. Plus, there's a valve system that helps a lot. There are two primary parts to the pump system: the atrium and the ventricle. Blood flows into the atrium, and then the ventricle. And then it leaves the heart for its primary destination.
There are two halves to the heart, with its own atrium and ventricle. There's even a piece of the heart called the septum that divides these halves! One side pumps used blood to the lungs to get cleaned and get an oxygen refill, and the other side sends oxygen-rich blood throughout our body.
How does the heart keep the blood going forwards instead of backwards and mixing things up? It's the valves! The valves open to let blood in, but close to keep the blood from taking a backwards trip. In fact, our heartbeat is actually the sound of the two valve sets closing... first the bigger set, and then the smaller set. Defective valves can be replaced via surgery... man-made valves for this purpose is made from pig fat. Sounds disgusting, I know, but it's a still-cool way of using stuff.
The heart, believe it or not, has its own mini-blood system that brings it blood and nutrients. You've got to remember that the heart is a muscle that works 24/7 without any breaks, so the stuff is needed. Now, the passages can get blocked... usually by a blockage of blood vessels called a blood clot. The muscle stops receiving what it needs, and dies... and that causes trouble. This problem is extremely well-known, especially by its name of heart attack!
The heart has a lot of blood vessels attached to it, whether the blood is being sent in or out. One of these is the atora (sp?), which is very strong! It can stand high pressure from the blood! This makes some sense, since it's one of the primary blood vessels.
Did you know that your heart has a skin too? It's true! The heart has a skin called the parcardium (sp?). This skin is a little different from our normal skin. It's two "bags" over the heart! Still, it's cool!