Source: Video and Images Created by Amanda Soderlind
Welcome to this lesson today on the cardiovascular system overview. Today we will be discussing the purpose and the structure of the cardiovascular system. The purpose of the cardiovascular system is to move blood throughout the body. Blood provides our tissues with oxygen and other necessary materials and it also aids in the removal of CO2. It's necessary that blood circulates through our body. In order to circulate that blood through our body, we have our cardiovascular system to do that for us, and the cardiovascular system is also sometimes called the circulatory system. So you may hear it either way. The cardiovascular system is composed of the heart and blood vessels. The heart is a muscular pump that pumps blood throughout the body. And blood vessels are tubes that transport the blood that's pumped by the heart.
There are actually various types of blood vessels. Blood vessels are just kind of a generic term to describe these tubes that transport blood. But there's actually various types of blood vessels that vary in their size, structure, and a little bit in their function. The types of blood vessels we have in our body are arteries, arterioles, capillaries, venules, and veins. We're going to use this diagram here to discuss these different types of blood vessels.
First of all, we have our heart here in our diagram. And when blood is flowing away from our heart it is flowing through arteries. Arteries are a type of blood vessel that carry blood away from the heart and they have a large diameter. This would be an example. This is just a very simple diagram of what an artery structure might look like. It's moving blood away from the heart.
Arterioles are similar to arteries in the fact that they also carry blood away from the heart, but arterioles are smaller in diameter. So up here we have the larger diameter arteries carrying blood away from the heart, which then eventually branches into these smaller diameter arterioles. And then those are arterioles will eventually branch into even smaller diameter capillaries.
Capillaries are the smallest blood vessel in our body and they are where substances are allowed to defuse from the blood into tissues. They're very, very, very small diameter, very thin layer, one membrane, one cell layer in capillaries. And then capillaries from there will start to branch back into venules which have a small diameter and actually substances can still diffuse through venules as well. But they do have a larger diameter than capillaries. So venules are actually starting to transport blood back to the heart. Arteries and arterioles are transferring blood away from the heart and venules are beginning to transport blood back to the heart. And
Then we get into veins. And veins have a larger diameter than venules. And the purpose again of veins is to transfer blood back to the heart. So these are our five different types of blood vessels. This lesson has been an overview on the cardiovascular system.
A large diameter blood vessel that carries blood away from the heart.
A smaller diameter blood vessel that carries blood away from the heart.
Tubes that carry blood to and from the heart and body.
The smallest blood vessel that acts as a zone of diffusion between blood and tissues.
A body system composed of the heart and blood vessels that acts to transport blood throughout the body.
A muscular pump that pumps blood throughout the body.
A large diameter blood vessel that returns blood to the heart.
A small diameter blood vessel that returns blood to the heart.