What is Cardiovascular System? | Types, Definition, Structure, Function & Facts

What is Cardiovascular System?

The cardiovascular system delivers nutrients throughout the body. The three main components of the cardiovascular system are the heart, blood vessels, and blood. Blood is what keeps the rest of our bodies alive. It must be continuously pumped by the heart throughout the body. Blood carries nutrients and oxygen to the cells of our body. Traffic


Blood is constantly circulating throughout our body. As it passes through our bodies, it takes nutrients from our food and sends them into the cells that need them. It also takes oxygen from our lungs and sends it into the cells to use as an energy source. The blood then takes the leftover carbon dioxide from the cells and delivers it to the lungs for us to exhale.

Blood Vessels

Blood vessels are the tubes that carry blood throughout our body. There are two main types of blood vessels: arteries and veins. Arteries carry blood from the heart to the rest of the body. The arteries must be thick and strong because they take more pressure from the heart. When you feel your pulse, it’s coming from an artery. The veins return used blood back to the heart. They don’t have to be too thick.

What is in Blood?

More than half of blood is made up of red blood cells that carry oxygen. This is why blood looks red. There are also white blood cells that kill germs and keep the blood clean. Blood also contains what are called platelets that help clot when you cut yourself. Ultimately, all of these cells float in a liquid called plasma.

The Heart

The heart is a large organ about the size of your fist. It is located in your rib cage, just to the left of the center of your chest. The heart is made up of many muscles that pump blood throughout our body. Veins bring blood back to the heart to be pumped back into the arteries. The main artery that leaves the heart is called the aorta. To make sure the blood doesn’t flow back there are valves that make sure the blood is only pumped in the right direction. There are four sets of valves in the heart.

The heart has two main pumps. One delivers blood throughout the body, while the other delivers blood from the veins to the lungs to remove carbon dioxide and get more oxygen.

The heart beats at different rates depending on the activity of the body. If you just sit, it will beat slowly. If you run fast, your heart will beat faster to deliver oxygen to your muscles.

What are Blood Types?

There are four main blood types: A, B, O and AB. Each blood type is slightly different and has different antibodies and antigens. It is important that blood donors have the right blood type, or a person can become seriously ill.

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