Understanding Infectious Diseases: Causes, Pathogens, and Prevention

1. Chapter 19 Fighting Disease

2. Section 1: Infectious Disease • Objectives: • Explain the cause of infectious disease and identify the kinds of organisms that cause disease • Describe methods in which pathogens enter the body

3. Disease and Pathogens Organisms that cause disease = pathogens A disease that can pass from one organism to another = infectious disease Infectious diseases are caused by pathogens

4. Disease and Pathogens • 4 major groups of human pathogens: • Bacteria • Viruses • Fungi • Protists • Each infectious disease is caused by a specific pathogen

5. Disease and Pathogens • Examples: • Bacteria causes strep throat • Viruses cause the flu • Fungus causes athlete’s foot • A protist causes malaria

6. Disease and Pathogens In 1860’s Louis Pasteur showed microorganisms cause certain diseases Pasteur developed a method of heating foods to kill microorganisms = pasteurization Influenced British surgeon Joseph Lister to sterilize his hands and instruments before surgery AND After surgery to cover wounds with treated bandages

7. Surgery in the 1800’s

8. Modern Surgery

9. How Diseases are Spread • You can become infected by a pathogen in one of several ways: • By another person • By contaminated objects • An animal bite • The environment

10. Person to Person Transfer • Direct physical contact: • Kissing • Hugging • Shaking hands • Indirect contact: • Sneezing • Coughing

11. Contaminated Objects Food Water Towels Silverware Stepping on contaminated nails

12. Animal Bites Rabies Lyme disease Rocky Mountain spotted fever

13. Pathogens from the Environment The bacteria that causes tetanus lives in soil and water The bacteria that causes botulism lives in soil

14. Section 2: The Body’s Defenses • Objectives: • Identify the body's barriers against pathogens • Describe the role of the inflammatory response in fighting disease • State how the immune system responds to pathogens. • Describe HIV and list the ways it can be spread

15. Barriers That Keep Pathogens Out Barriers such as the skin, breathing passages, mouth, and stomach trap and kill most pathogens with which you come into contact

16. The Skin Chemicals in oil and sweat can kill pathogens Pathogens can fall off with dead skin Washing with soap and water decreases pathogens Scabs over cuts prevent pathogens from entering the body

17. The Breathing Passages Mucus and cilia in the nose, pharynx, and bronchii trap and remove pathogens that enter the respiratory system Sneezing and coughing force pathogens out of your body

18. The Mouth and Stomach Saliva and stomach acid kill most pathogens that you swallow

19. General Defenses In the inflammatory response, fluid and certain types of white blood cells leak from blood vessels into nearby tissues. The white blood cells then fight the pathogens White blood cell that engulfs and destroys pathogens = phagocyte

20. The Immune System The cells of the immune system can distinguish between different kinds of pathogens. The immune system cells react to each kind of pathogen with a defense targeted specifically at that pathogen White blood cells that recognize pathogens = lymphocytes

21. T Cells Distinguish between different kinds of pathogens Molecules on cells the immune system recognizes as either part of your body or outside your body = antigens

22. B Cells Produce chemicals that help destroy pathogens Chemicals are called antibodies Each B cell produces only 1 specific antibody

23. AIDS, a Disease of the Immune System AIDS = a disease caused by a virus that attacks the immune system Caused by the HIV virus Attacks and destroys T cells

24. Section 3:Preventing Infectious Disease • Objectives: • Define and explain active immunity • Define and explain passive immunity • Identify some strategies for staying healthy

25. Active Immunity The body’s ability to destroy pathogens before they can cause disease = immunity When a person’s own immune system produces antibodies in response to the presence of a pathogen = active immunity

26. How Active Immunity is Produced T cells and B cells remember the antigens they come into contact with When they encounter that antigen again the immune response is very quick and you usually don't get sick

27. Vaccination The process by which harmless antigens are deliberately introduced into a person’s body to produce active immunity = vaccination The substance used in the vaccination = vaccine Usually contains dead or weakened forms of the pathogen

28. Passive Immunity When a person is given the antibodies = passive immunity Occurs when the antibodies that fight the pathogen come from another source rather than from the person’s own body

29. Staying Healthy Don’t share items that might carry pathogens like toothbrushes, drinking straws, and silverware Wash hands before eating and after using the bathroom Cover your mouth when sneezing and coughing Get 8 hours of sleep every night Eat a well-balanced diet Get regular exercise

30. Section 4: Noninfectious Disease Define an allergy Explain how diabetes affects the body Explain how cancer affects the body

31. Noninfectious disease – diseases not spread from person to person Not caused by microorganisms What are Noninfectious Diseases?

32. Allergies • Allergies – disorder in which the immune system is overly sensitive to a foreign substance • Allergen – any substance that causes an allergy • Histamine – chemical that is responsible for the symptoms of an allergy

33. Asthma – disorder in which the respiratory passages narrow significantly Short of breath Brought on by stress, exercise, allergies Asthma

34. Diabetes Diabetes – a condition where pancreas fails to produce insulin or body cells can’t use it properly Insulin – a chemical that allows body cells to take in glucose from blood Person excretes glucose in urine Body cells do not have enough glucose for energy

35. Insulin Pump

36. Lose weight Weak Hungry Urinate frequently Feel thirsty Long-term effects Effects of Diabetes

37. Two Forms of Diabetes • Type I • More serious • Begins in childhood • Type II • Develops during adulthood • May not need to take insulin

38. Cancer Cancer – disease in which cells divide uncontrollably Tumors – abnormal tissue masses Often caused by carcinogens – a substance or a factor in the environment that can cause cancer