1. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood? Copyright © Houghton Mifflin Harcourt Publishing Company

2. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company The heart is a muscular organ that pumps blood throughout the body. It contracts in two phases. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

4. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company When the top part relaxes, it fills with blood. When it contracts, the top part squeezes blood to the lower part. When the lower part contracts, it squeezes blood from the heart into vessels and all parts of the body. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

5. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company Blood it carries nutrients and other substances to the cells. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

6. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company Blood is made up of a clear liquid called plasma and small structures called blood cells. Red blood cells carry oxygen throughout the body. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

7. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company White blood cells help fight disease. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

8. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company Platelets stop bleeding by forming clots. Plasma carries nutrients throughout the body. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

9. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company 2- Blood vessels carry the blood to every part of your body. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

10. Blood vessels Copyright © Houghton Mifflin Harcourt Publishing Company Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

11. Beat It Copyright © Houghton Mifflin Harcourt Publishing Company Arteries carry blood away from the heart. Veins bring blood back to the heart from the lungs and the body. Oxygen, nutrients, and carbon dioxide pass through capillaries, or tiny vessels with very thin walls, to parts of the body and into the blood. The heart, vessels, and blood are all part of the circulatory system. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

13. Breathe In, Breathe Out Copyright © Houghton Mifflin Harcourt Publishing Company Organs in the respiratory system bring in oxygen and release carbon dioxide. Air enters the body through the nose or mouth and flows through a tube in the throat called the trachea. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

15. Breathe In, Breathe Out Copyright © Houghton Mifflin Harcourt Publishing Company Lungs, the main organs of the respiratory system, are spongy organs that expand to fill with air. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

16. Breathe In, Breathe Out Copyright © Houghton Mifflin Harcourt Publishing Company The trachea branches into two smaller tubes called bronchi. Bronchi branch into many bronchioles in the lungs. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

17. Breathe In, Breathe Out Copyright © Houghton Mifflin Harcourt Publishing Company Tiny sacs called alveoli are attached to bronchioles. They inflate and deflate as you inhale and exhale. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

18. Breathe In, Breathe Out Copyright © Houghton Mifflin Harcourt Publishing Company Red blood cells in the alveoli absorb oxygen. Identify the blood vessels and alveoli. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

19. Asthma Attack Copyright © Houghton Mifflin Harcourt Publishing Company Asthma is an illness that makes it hard for a person to breathe. During an asthma attack, bronchi become swollen, making airways smaller. This makes it much harder to get air in and out of the lungs. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood? Constricted Airways

20. Asthma Attack Copyright © Houghton Mifflin Harcourt Publishing Company Why is it more difficult to breathe during an asthma attack? Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood?

21. Asthma Attack Copyright © Houghton Mifflin Harcourt Publishing Company The exact causes of asthma aren’t known. Some people are born with asthma, while for other people, smoke, air pollution, and allergies can trigger an asthma attack. Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood? Triggers

22. Asthma Attack Copyright © Houghton Mifflin Harcourt Publishing Company Unit 3 Lesson 4 How Do Our Bodies Move, Breathe, and Circulate Blood? People can try to avoid asthma triggers; however, people can’t always avoid pollen or air pollution. A doctor can prescribe an inhaler, a device that delivers medication to the lungs. The inhaler releases a mist that can help open up airways. Management