Lesson 3.4 - The Circulatory System

Your body cells work to perform life functions that keep you alive and healthy.  In order to do that your body cells need oxygen, food, and nutrients.  As the cells do their work, they produce wastes that must be removed.  The circulatory system is responsible for delivering the required substances to the cells and removing the wastes.  How does the circulatory system work?  Read "The Circulatory System - The Beat Goes On" on page 188 and the top paragraph on page 189 of your textbook.

Question 1. What is the role of the circulatory system?

Question 2. What are the four components of the circulatory system?

Question 3. What does it mean when the circulatory system is called a closed system?

Question 4. What is the function of the arteries?

Question 5. What is the function of the veins?

Question 6. What is the function of the capillaries?      

 

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The heart pumps blood through the arteries.  This blood is under pressure so the arteries have to be strong enough to withstand the pressure.  Blood that is returning to the heart through the veins is not under as much pressure so veins are not as strong as arteries.  To learn more about how the heart pumps blood go to the following website:

http://www.howstuffworks.com/heart.htm

 

Question 7. How does your heart pump blood?

Question 8. Which blood vessels are the strongest?  Which are the weakest?

 

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Answers to Questions:

 

Question 1. What is the role of the circulatory system?

The role of the circulatory system is to move blood throughout the body.

Question 2. What are the four components of the circulatory system?

The four components of the circulatory system are:

  • heart

  • arteries

  • veins

  • capillaries

Question 3. What does it mean when the circulatory system is called a closed system?

The circulatory system is a called a closed system because all the blood that is pumped by the heart eventually returns to the heart.  Another way to look at it is that blood is not leaving the body, it just keeps going within the body.

Question 4. What is the function of the arteries?

The function of the arteries is to carry oxygen-rich blood to all parts of the body from the heart.

Question 5. What is the function of the veins?

The function of the veins is to carry oxygen-poor blood from the body back to the heart.

Question 6. What is the function of the capillaries?

The function of the capillaries is to connect the arteries and the veins.  The capillaries are so thin that the nutrients and wastes are exchanged between the body cells and the blood.

 

 

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Answers to Questions:

Question 7.How does your heart pump blood?

Your heart is a hollow muscle that has valves in it.  When the muscles contract the valves of the veins close while the valves of the arteries open.  Blood inside the heart is squeezed out through the arteries.  When the heart muscle relaxes the valves to the arteries close while those from the veins open.  This draws more blood into the hollow of the heart and the process repeats itself.

Question 8. Which blood vessels are the strongest?  Which are the weakest?

The arteries are the strongest blood vessels.  The capillaries are the weakest blood vessels.

 


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