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You learned about the digestive system and how that system works with the circulatory system. In this activity, you will learn more about the circulatory system.

The Circulatory System

The circulatory system's job is to move blood throughout the body. The system consists of the heart and blood vessels called arteries, veins, and capillaries. Together, these parts form a transport system to move the blood. Blood that is pumped from the heart eventually returns to the heart.

Here's how the circulatory system works:

1. The heart receives oxygen-rich blood from the lungs. The arteries take this blood away from the heart to the body tissues.

2. The veins return the oxygen-poor blood from the body tissues to the heart. From there, the blood is pumped to the lungs to receive oxygen.

3. This cycle begins over again.

4. The capillaries are very small vessels that connect the veins and arteries.

Digging Deeper

Try This!

Click here to go to the Study Jams! website to watch a video that further explains the circulatory system.

When you have finished watching the video, click on the "close" button in the upper right-hand corner to exit the video. Then, click on the "Test Yourself" button to see how much you know about the circulatory system.

Digging Deeper

In a scientific investigation, there are three types of variables: manipulated, responding, and controlled. These variables are identified to make sure the results are accurate (correct) and that the experiment could be repeated in exactly the same way, with the same results.

Manipulated variable: what is changed or being tested in order to see what the effect will be

Responding variable: the results that occur because of the manipulated variable

Controlled variable: factors that are kept the same to make sure the results are accurate

Here's an example:

You are conducting an experiment to determine how four fertilizers affect the growth rate of bean plants and want to answer this question: How will four fertilizers affect the growth rate of bean plants?

Manipulated variable: In this experiment, this is what is changed or being tested in order to see what the effect will be are the four types of fertilizer.

Responding variable: In this experiment, the results that occur because of the manipulated variable will be the height of the plants.

Controlled variable: In this experiment, factors that are kept the same to make sure the results are accurate include:

the type of seeds used
the amount of soil
the amount of light received by the plant
the amount of water per day
the amount of fertilizer.

(adapted from K&E Studio)

You will practise identifying variables in the next assignment.