Basics of the Circulatory System

Lesson Plan - Get It!

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Water parks have complex pump and pipe systems that move water throughout the park to water slides, rides, and pools.

The circulatory system operates in a very similar way, pumping blood from a central location to all areas of the body.

The circulatory system is comprised of your heart and blood vessels. Blood vessels include arteries, veins, and capillaries, that all serve specific purposes within the system.

The circulatory system depends on the heart, an organ, to pump blood throughout the body.

The heart is an involuntary muscle, which means it beats without direct instruction from the brain. Most people's hearts beat between 60 and 100 times per minute.

It is located between the lungs in the chest cavity.

The human heart comprises thick muscle divided into four chambers.

Notice the ventricle and atria components of the heart in the image above.

The atria are located at the top of the heart and divided into the left and right atrium. The bottom of the heart is divided into the left ventricle and right ventricle.

The ventricles pump blood out of the heart, while the atria receive blood moving into the heart from the body.

The body's largest blood vessel is also found in the heart: the aorta.

The aorta is an artery vessel that carries oxygenated blood away from the heart. This blood provides the oxygen and nutrients to the body that organs and tissues need to function.

Arteries have thick walls and branch into smaller arterioles farther away from the heart.

Veins move de-oxygenated blood back to the heart through a series of valves that prevent blood from flowing backward. De-oxygenated means that the blood has already given the dissolved oxygen to organs and tissues throughout the body.

Veins are less flexible and have a thinner smooth-muscle layer than arteries. The superior vena cava and inferior vena cava are the largest veins and are located above and below the heart.

Review the earlier image to review where they are in the body.

Veins and arteries are connected by capillaries, the smallest type of blood vessel.

These tiny structures allow veins and arteries to exchange water, carbon dioxide, nutrients, and a small amount of oxygen. They are also responsible for delivering oxygen and nutrients to cells and removing waste products from cells.

These components move blood throughout the human body. The heart pumps large amounts of blood out to the arms and legs, providing necessary oxygen to these areas.

Arteries move blood away from the heart, while veins take the blood back to the heart. Capillaries are important structures for providing oxygen and nutrients to cells and provide arteries and veins with a way to exchange blood.

Your heart is an amazing muscle, providing the nutrients and blood supply for your entire body. Arteries, veins, and capillaries act as pathways, moving the valuable fluid to tissues and organs.

• Have you ever felt your pulse increase in your wrist or neck?
• Why do you think your heart beats faster when excited or scared?
• How can you help control the pace of your heartbeat?

In the Got It? section, complete a guide that will help you learn more about the structure of the heart and the way it pumps blood!