The cardiovascular system

aka the “circulatory system”

The two sides of the heart

• When you look at the heart on a piece of paper, the left and right sides are switched

• This is called anatomical right and left

Left sideRight side

Four main parts of the heart

• Atria = upper chambers (left and right)

• Singular is one atrium

• Ventricles = lower chambers (left and right)

Ventricles

Atria

Atria

Blood flow through the heart

• Blood enters the atria (top) first

• When the atria contract, the blood is squeezed into the ventricles

• When the ventricles contract, the blood flows out of the heart

Blood flow continued

• Blood picks up oxygen in the lungs and then delivers the oxygen to the body

FYI: Carbon dioxide is also dropped off in the lungs so it can be exhaled!

Valves

• Valves are flap-like structures that prevent blood from going backwards

• You can find them between the atria and ventricles

• They are also between the large arteries and the ventricles

Valves continued

• The lub-dub sounds of the heart are caused by the opening and closing of the valves

Valves

Valves

Heart diagram

1. Remember that the right and left sides of the heart are switched when on paper. Label the right and left sides of the heart.

2. The atria are the upper chambers of the heart. The ventricles are the lower chambers. Label the left and right atria and right and left ventricles.

Heart diagram continued

3. Oxygen rich blood flows from through a vein from the lungs into the left atrium. Color the left atrium and the vein that carries the blood from the lungs red.

4. Blood flows from the left atrium to the left ventricle. Color the left ventricle red.

Heart diagram continued

5. Blood flows through an artery from the left ventricle to the body. The body takes up the oxygen in the blood. Color this artery red.

6. Blood flows through two large veins from the body into the right atrium. Color the right atrium and the two large veins blue.

***Remember that blood is never blue. We are using blue color to represent blood with little oxygen in it.

Heart diagram continued

7. Blood flows from the right atrium to the right ventricle. Color the right ventricle blue.

8. Blood flows through an artery from the right ventricle to the lungs. In the lungs, the blood picks up oxygen. Color this artery blue because it doesn’t have oxygen yet.

Heart diagram continued

9. Add arrows to your diagram to show the blood flow through the heart. Start with the left atrium.

10. Indicate whether each blood vessel is carrying blood to or from the lungs or to and from the body.