What You’ll Learn

1. What You’ll Learn 1. Explain how the immune system responds when a pathogen enters the body. 2. Discuss ways to develop active and passive immunity. 3. Identify types of pathogens that cause disease, and give examples of the types of diseases caused by the types of pathogens.

2. What You’ll Learn 4. Discuss ways pathogens are spread. 5. Analyze strategies to prevent infection with communicable diseases.

3. The Immune System • The immune system is the system that removes harmful organisms from the blood and combats pathogens. • The immune system is composed of body organs, tissues, cells, and chemicals.

4. Key Terms • fungi • protozoa • lymphocytes • B cell • antibody • helper T cell • macrophage • vaccine • pathogen • bacteria

5. Protection Inside the Body • The Immune System • Lymphocytes are white blood cells that help the body fight pathogens. • When a pathogen enters the body, lymphocytes multiply in lymph tissue to fight infection. Two types of lymphocytes are B cells and helper T cells. • A B cell is a white blood cell that produces antibodies.

6. Protection Inside the Body • The Immune System • An antibody is a special protein that helps fight infection. • A helper T cell is a white blood cell that signals B cells to produce antibodies. • After a pathogen invades the body, helper T cells send signals to B cells to produce antibodies. Antibodies then travel through the blood to destroy the pathogen. Antibodies can make pathogens ineffective and sensitive to macrophages.

7. Protection Inside the Body • The Immune System • A macrophage is a white blood cell that surrounds and destroys pathogens. • Antibodies attach to pathogens and make them easier for macrophages to destroy. Destroyed pathogens enter lymph, are filtered in lymph nodes, and are removed by the spleen.

8. Protection Inside the Body • Immunity • The immune system helps people develop immunity. • Immunity is the body’s resistance to disease-causing agents. • Active immunity is resistance to disease due to the presence of antibodies. • Active immunity can result from being previously infected or from being given a vaccine.

9. Protection Inside the Body • Immunity • A vaccine is a substance containing dead or weakened pathogens that is introduced into the body to give immunity. • Vaccines are either given by injection or orally. • Vaccines cause the body to make antibodies for a specific pathogen. If these pathogens enter the body again, the antibodies destroy them.

10. Protection Inside the Body • Immunity • People should be immunized against polio, diphtheria, pertussis (whooping cough), mumps, tetanus, measles, rubella (German measles), hepatitis A, hepatitis B, and chicken pox. • Passive immunity is immunity that results from introducing antibodies into a person’s bloodstream. • This type of immunity is short-term and is used when the risk of developing a disease is immediate.

12. Containing Pathogens • A pathogen is a germ that causes disease. • A communicable disease, or infectious disease, is an illness caused by pathogens that can be spread from one living thing to another. • There are many types of pathogens that cause diseases.

13. What to Know About Types of Pathogens • Bacteria • Bacteria are single-celled microorganisms. • Most bacteria are beneficial, but some are known to cause disease. • Bacteria cause disease by releasing toxins, or poisonous substances. • Some diseases caused by bacteria are strep throat, tuberculosis, tetanus, diphtheria, Lyme disease, syphilis, and gonorrhea.

14. What to Know About Types of Pathogens • Bacteria • Rickettsia are intracellular parasites that are classified as bacteria. • Two diseases caused by rickettsia are typhus and Rocky Mountain spotted fever.

15. What to Know About Types of Pathogens • Fungi • Fungi are a category of pathogens that include single- or multi-celled parasitic organisms. • Fungi obtain their food from organic materials, such as plant, animal, or human tissue. • Fungi can live on the skin, in mucous membranes and the lungs, and cause diseases in the process. • Some diseases caused by fungi are athlete’s foot, ringworm, jock itch, and nail infections.

16. What to Know About Types of Pathogens • Viruses • One of the smallest known pathogens is a virus. • When a virus enters a cell, it takes over the cell and causes it to make more viruses. Newly produced viruses are released and take over other cells. In this way, viruses spread rapidly. • Some viral diseases are the common cold, mumps, hepatitis, mononucleosis, chicken pox, and influenza.

17. What to Know About Types of Pathogens • Protozoa • Protozoa are tiny, single-celled organisms that produce toxins that cause disease. • Malaria, African sleeping sickness, and dysentery are diseases caused by protozoa. • A helminth is a parasitic worm that can infect people when they eat under-cooked meat or fish or practice poor hygiene.

18. What to Know About Types of Pathogens • How pathogens are spread  • Pathogens may be spread from person to person through direct contact, shaking hands, intimate kissing, sexual intercourse, receiving a transfusion of the person’s blood, touching ulcers or sores, or handling bodily fluids, such as blood or urine. • They may be spread through the air by coughing or sneezing. • Handling or being bitten by an infected insect or animal also spreads pathogens.

19. What to Know About Types of Pathogens • How pathogens are spread  • Pathogens can spread through contact with contaminated food and water by drinking infected water, eating infected food, undercooking meats and other foods, improperly canning or preparing foods, and not washing hands after using the restroom.

20. 2D Study Guide 1. Match the following terms and definitions. ___ immunity ___ active immunity ___ passive immunity ___ helminth ___ rickettsia A. intracellular parasites that are classified as bacteria B. a parasitic worm C. resistance to disease due to the presence of antibodies D. the body’s resistance to disease-causing agents E. resistance to disease due to introducing antibodies into a person’s bloodstream D C E B A

21. 2D Study Guide 2. Identify the following statements as true or false. _______ The immune system is composed of body organs, tissues, cells, and chemicals. _______ Most bacteria are beneficial. _______ Malaria, African sleeping sickness, and dysentery are diseases caused by bacteria. _______ Passive immunity is short-term and is used when the risk of developing a disease is immediate. true true false true

22. Study Guide 3. Explain how viruses spread rapidly and give two examples of viral diseases. When a virus enters a cell, it takes over the cell and causes it to make more viruses. Newly produced viruses are released and take over other cells. In this way, viruses spread rapidly. Some viral diseases are the common cold, mumps, hepatitis, mononucleosis, chicken pox, and influenza.

23. End of the Lesson

24. Lesson Resources tx.healthmh.com/body_systems tx.healthmh.com/pathogens tx.healthmh.com/study_guide

25. Help To navigate within this Interactive Chalkboard product: Click the Forward button to go to the next slide. Click the Previous button to return to the previous slide. Click the Lesson Resources button to go to the Lesson Resources slide where you can access resources, such as transparencies, that are available for the lesson. Click the Menu button to close the lesson presentation and return to the Main Menu. If you opened the lesson presentation directly without using the Main Menu, this will exit the presentation. You also may press the Escape key [Esc] to exit and return to the Main Menu. Click the Help button to access this screen. Click the Health Online Button to access the Web page associated with the particular lesson you are working with. Click the Speaker button to hear the vocabulary term and definition when available.

26. This slide is intentionally blank.