The Cardiovascular System and the Heart

A body can be looked at a lot like a highway. A highway is a system within a system, just like your body has systems within systems. The body has eleven different systems.

One of these systems, like a highway, acts like a transportation system.

The cardiovascular, or circulatory system, has three different parts that work together to make the body work right.

Cardiovascular System

The cardiovascular system has a large heart muscle, blood and a bunch of different tubes, that make up the cardiovascular system.

These tubes are called blood vessels and the blood vessels help to circulate blood throughout the body, taking oxygen and nutrients to the different cells that are located throughout the body.

Functions of the Cardiovascular System

The cardiovascular system has three main functions in the body.

The first function is that it helps to make the heart pump blood, then, the blood circulates around the body with the help of the blood vessels, delivering oxygen and nutrients and removing different waste from the heart such as water, carbon dioxide, and even salt can be carried away.

The blood also helps fight different diseases in the body because it holds different special cells that help to fight the diseases.

Highway of Blood Vessels

Red cells ride through the “highway” of the blood vessels, the cardiovascular system, taking blood through all parts of your body.

The cardiovascular system is made up of blood vessels and the heart, and the blood vessels are like tiny tunnels that run all through the body.

The blood vessels are made up of arteries, which take oxygen to different parts of your body and veins that takes carbon dioxide from your heart to your lungs.


The heart is the most important muscle in your body.

The heart is an involuntary muscle, which means that it moves by itself. It is constantly moving, even though you do not feel it, and it moves when you are moving or even when you are sleeping.


When your heart moves, it is called a heartbeat and the heart beats at over 100,000 times in one day.

When the heart beats, it pulls blood in and then pushes blood out of the heart, and this helps the blood move fast enough to go throughout the whole entire body and back to the heart.

With this movement, the red blood cells move through the body to carry nutrients and oxygen.

Chambers of the Heart

The heart has different sides or chambers. The right side is called the right atrium and then it opens into the tricuspid valve, the lower right area is called the right ventricle, and then the pulmonary valve.

The heart beat makes the heart pump the blood through these different areas of the heart and then it goes into the arteries which leads to other parts of the body.

Bring Oxygen

The red blood cells travel from the heart to the lungs to gather oxygen to take to another part of the body.

All bodies need oxygen and the lungs help by bringing the oxygen into the body and the blood vessels help take it to where it is needed.

Carbon Dioxide

The other side of the heart is where the blood cells carry the oxygen to.

This part of the heart has the left atrium, the mitral valve, the left ventricle and the aortic valve.

The red blood cells gather carbon dioxide at this time and carries this back to the lungs.

The heart has different valves that are similar to trap doors that allow the red blood cells to move in the direction that they are going and stops the cells from moving the wrong way.

All of these parts of the body work together in order to make the heart beat and to help blood pump all through the body.

Facts About the Cardiovascular System and the Heart

  • Cardiovascular system is the system of vessels and organs that help to transport materials throughout the body.
  • Circulate means to move repeatedly.
  • The immune system helps to protect us from bacteria and viruses.
  • Exercise is important to help keep the heart strong.
  • The atrium is one of the two chambers of the upper heart.
  • The ventricle is one of the two chambers of the lower heart.
  • When blood enters the right atrium, the blood is deoxygenated.
  • Deoxygenated means that there is not oxygen.
  • When the blood comes back from the lungs, it is oxygenated.
  • Oxygenated means rich in oxygen.
  • The reason that the blood is red is because red blood represents oxygenated blood.
  • When the blood is blue, it is deoxygenated blood.
  • The heart is only around the size of a fist.
  • The walls of the heart have many muscles and there are thin, white strings that are attached to the valves to help them do their job.

What Did You Learn?

  • What circulates around our bodies every day? Red blood cells circulate around our bodies every day, over 100,000 times a day.
  • What are the different chambers of the heart called? The heart has four hollow chambers, the right atrium and the left atrium, the right ventricle and the left ventricle.
  • What is the name of the small tunnel like tubes that are found in the body? The small, tunnel like tubes are called blood vessels.
  • What color is the blood when it is oxygenated? The blood that is oxygenated is the color red.
  • What color is the blood when it is deoxygenated? Deoxygenated blood is blue.
  • What is the name of the system that contains the heart, the blood and blood vessels? The cardiovascular system contains the heart, blood and blood vessels.