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Communicable Diseases

Communicable Diseases. Chapter 12: Lesson 1. BELL ACTIVITY. List as many different diseases as you can. Health Goal # 31. I will choose behaviors to reduce my risk of infection with communicable disease. P. 328. Germs & Disease p. 332.

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Communicable Diseases

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  1. Communicable Diseases Chapter 12: Lesson 1

  2. BELL ACTIVITY • List as many different diseases as you can.

  3. Health Goal # 31 • I will choose behaviors to reduce my risk of infection with communicable disease. P. 328

  4. Germs & Disease p. 332 • Just about everyone has had some experience with disease. • A disease is any condition that interferes with the proper functioning of the body or mind. • Communicable diseases are caused by microorganisms, organisms so small that they can be seen only through a microscope.

  5. Infection p. 332 • An infection results when germs get inside the body, multiply, and damage body cells. • If the body is unable to fight off the infection, a disease occurs.

  6. Did you know? • Bacteria are tiny, but they reproduce amazingly fast. In several hours, just one bacterium can multiply to 250,000!

  7. Viruses, Bacteria, and Other Germs • Not all germs are the same. • The types of germs that cause diseases include viruses, bacteria, fungi, and protozoa. • Most diseases that occur in the U.S. are caused by viruses or bacteria.

  8. Figure 12.1 Causes of Disease p. 333 • A. Viruses • Bacteria • Fungi • Protozoa

  9. How germs are spread p. 334 • Figure 12.2 Spreading Germs • Direct Contact • Indirect Contact • Other Contacts • Contact with Animals or Insects

  10. Lesson 2: The Immune System p. 336

  11. What are antibodies? • An antibody is a protein complex used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target.

  12. Antibodies • Antibodies that recognize viruses can block these directly by their sheer size. • The virus will be unable to dock to a cell and infect it, hindered by the antibody

  13. Defending Against Invaders • Each day your body is exposed to countless germs. To protect itself against these germs, your body takes action to repel, trap, or destroy them. • The body has natural barriers that keep germs out or destroy them before they can do any damage.

  14. The 5 major barriers, or “first lines of defense” p. 336 • Skin • Mucuous membranes • Saliva • Tears • Stomach acid

  15. The Immune System’s General Reactions p. 337 • When germs get inside your body, your immune system launches an attack. Three general reactions may occur, no matter what kind of microorganism has invaded. • 1. Special white blood cells called phagocytes attack the invading germs. These cells actually surround the germs and destroy them. • 2. The cells may release a chemical substance called interferon that stops viruses from reproducing. • 3. Rising body temperature, commonly called a fever, makes it difficult for some microorganisms to reproduce.

  16. Fighting against specific germs p. 337 • To fight against specific germs, the body calls upon the lymphatic system. • The lymphatic system is a secondary circulatory system that helps the body fight germs and maintain its fluid balance. • The lymphatic system carries a watery fluid known as lymph.

  17. Lymphocytes p. 337 • Special white blood cells in the lymph are called lymphocytes. • 2 types: B-cells & T-cells • Both are important in fighting off germs and disease The lymph also contains phagocytes known as macrophages, which help the lymphocytes identify invading germs.

  18. Antigens & Antibodies p. 337 • Antigens are substances that send your immune system into action when your body is invaded by germs. • The body recognizes antigens as invaders. • Anitbodies are proteins that attach to antigens, keeping them from harming the body. • Your immune system produces specific antibodies to fight each antigen.

  19. Figure 12.3 p. 338 • How the Immune System Responds to Germs 1-7

  20. Immunity p. 339 • Your body’s ability to resist the germs that cause a particular disease is called immunity. • You develop immunity in 2 ways: • Natural exposure to germs • Immunization

  21. Closing • WRITE QUESTIONS AND TURN IN WHEN FINISHED. • 1. What are the body’s 5 barriers against disease? • 2. List 3 general reactions of the immune system. • 3. Define the terms antigen and antibody.

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