Unit 10 The Human Body

1. Unit 10 The Human Body Ch. 40 The Immune System & Disease

2. Infectious Disease • Disease - any change, other than an injury, that disrupts homeostasis • Some diseases are produced by agents like: bacteria, viruses, & fungi

3. Pathogens • Pathogens - disease-causing agents • Diseases caused by pathogens are generally infectious disease

4. The Germ Theory of Disease • For thousands of years, people believed that diseases were caused by curses, evil spirits, or night vapors • Chemist, Louis Pasteur & bacteriologist, Robert Koch, concluded that diseases were caused by different types of microorganisms, called germs

5. Koch’s Postulates • 1. The pathogen should always be found in the body of a sick organism, not in a healthy one • 2. The pathogen must be isolated & grown in the lab in pure culture

6. Koch’s Postulates • 3. When the cultured pathogens are placed in a new host, they should cause the same disease that infected the original host • 4. The injected pathogen should be isolated from the second host. It should be identical to the original pathogen.

7. Agents of Disease • Some pathogens, including viruses & some bacteria, destroy cells as they grow • Other bacteria release toxins that harm an organism

8. Agents of Disease • Still others, especially parasitic worms, produce sickness when they block the flow of blood, remove nutrients from the digestive system, & disrupt other bodily functions

9. How Diseases Are Spread • Some infectious diseases are spread from 1 person to another through coughing, sneezing, or physical contact • Other infectious diseases are spread through contaminated water or food

10. How Diseases Are Spread • Still others are spread by infected animals • Vectors - animals that carry pathogens from person to person

11. Fighting Infectious Diseases • Antibiotics - compounds that kill bacteria without harming the cells of the human or animal hosts

12. The Immune System • The function of the immune system, is to fight infection through the production of cells that inactivate foreign substances or cells - immunity • The immune system includes 2 general categories of defense mechanisms: nonspecific & specific defenses

13. Nonspecific Defenses • Nonspecific defenses do not discriminate between 1 threat & another • These defenses include physical & chemical barriers

14. Nonspecific Defenses • First Line of Defense: • The function is to keep pathogens out of the body • This role is carried out by skin, mucus, sweat, & tears • Your body’s most important nonspecific defense is the skin

15. Nonspecific Defenses • Second Line of Defense: • If pathogens enter your body, they multiply quickly, releasing toxins into your tissues • When this happens, it activates the inflammatory response • Inflammatory response - a reaction to tissue damage caused by injury or infection

16. Nonspecific Defenses • Second Line of Defense: • When pathogens enter the body, phagocytes (white blood cells), move into the area & engulf (eat) the pathogens

17. Inflammatory Response

18. Nonspecific Defenses • Second Line of Defense: • The immune system also releases chemicals that increase the core body temp. - Fever • An elevated body temp. slows down or stops the growth of some pathogens • Fever & increased # of WBC’s indicates an infection

19. Nonspecific Defenses • Second Line of Defense: • Sometimes, virus-infected cells produce a group of proteins that help other cells resist viral infection • Interferons - “interfere” with the growth of viruses; they inhibit the synthesis of viral proteins in infected cells & help block viral replication

20. Specific Defenses • If a pathogen gets past the body’s nonspecific defenses, the immune system reacts with specific defenses that attack that particular disease-causing agent - Immune response

21. Specific Defenses • Antigen - a substance that triggers this response, includes: viruses, bacteria, & other pathogens • 2 types of lymphocytes recognize specific antigens: B lymphocytes (B cells) & T lymphocytes (T cells)

22. Specific Defenses • B cells provide immunity against antigens & pathogens in the body fluids - Humoral immunity • T cells defend against abnormal cells & pathogens inside living cells - Cell-mediated immunity

23. Specific Defenses • Humoral Immunity: • When a pathogen invades the body, it is recognized by B cells • These B cells grow & divide rapidly, producing large #’s of plasma cells & memory B cells

24. Specific Defenses • Humoral Immunity: • Plasma cells release antibodies • Antibodies - proteins that recognize & bind to antigens, they are carried in the bloodstream to attack the pathogen causing the infection • Once the body has been exposed, memory B cells remain capable of producing antibodies specific to that pathogen

25. Specific Defenses • Cell-mediated Response: • T cells provide defense against abnormal cells & pathogens inside living cells

26. Specific Defenses • Although killer T cells are helpful in the immune system, they make acceptance of organ transplants difficult • Your immune system damages & destroys the transplanted organ • The process is known as rejection

27. Acquired Immunity • Vaccination - the injection of a weakened pathogen to produce immunity • Active immunity - immunity produced by the body’s reaction to a vaccine • Passive immunity - when antibodies produced by other animals are injected into the bloodstream

28. Acquired Immunity • Active Immunity: • It appears after exposure to an antigen, as a result of the immune response • Active immunity may develop as a result of natural exposure to an antigen (fighting an infection) or from deliberate exposure to the antigen (through a vaccine)

29. Acquired Immunity • Passive Immunity: • It only lasts a short time because eventually, the body destroys the foreign antibodies • Like active immunity, it may develop naturally or by deliberate exposure

30. Acquired Immunity • Passive Immunity: • 1 kind of natural immunity occurs when the mother passes antibodies to the fetus through the placenta, or through breast milk

31. Immune System Disorders • There are 3 different types of immune system disorders: allergies, autoimmune diseases, & immunodeficiency diseases

32. Allergies • Allergies - overreactions of the immune system to antigens • Common allergies include: pollen, dust, mold, & bee stings

33. Allergies • When allergy-causing antigens enter the body, they attach themselves to cells that initiate the inflammatory response • Those cells release chemicals called histamines

34. Allergies • Histamines - chemicals that increase the flow of blood & fluids to the surrounding area • They also increase mucus production, resulting in sneezing, watery eyes, runny nose, & other irritations

35. Asthma • Asthma - a chronic respiratory disease where the air passages become narrower than normal • It causes wheezing, coughing, & difficulty in breathing • Asthma attacks can be triggered by infections, exercise, stress, etc.

36. Autoimmune Diseases • Autoimmune disease - when the immune system makes a mistake & attacks the body’s own cells • Multiple sclerosis is an example where antibodies destroy the functions of the neurons in the brain & spinal cord

37. AIDS, an Immunodeficiency Disease • 1 type of immunodeficiency disease, the immune system fails to develop normally • The 2nd type of immunodeficiency disease is AIDS

38. AIDS, an Immunodeficiency Disease • AIDS results from a viral infection (HIV) that destroys helper T cells • As the # of helper T cells declines, the normal immune response breaks down • When a person has AIDS, they die from the inability to fight off infection, like the flu, a cold, etc.

39. AIDS, an Immunodeficiency Disease • AIDS - Acquired ImmunoDeficiency Syndrome • HIV - Human Immunodeficiency Virus (causes AIDS)

40. HIV Infection

41. AIDS, an Immunodeficiency Disease • There are 4 main ways HIV can be transmitted: • 1. Sexual intercourse with an infected individual • 2. Shared needles or syringes • 3. Contact with blood or blood products • 4. Infected mother to child, during pregnancy, birth, or breast-feeding

42. AIDS, an Immunodeficiency Disease • The only no-risk behavior with respect to HIV & AIDS is abstinence (no sex) • At the present time, there is no cure for AIDS

43. The Environment & Your Health • Risk factor - factors that have potential to affect health in a negative way • Environmental factors that can affect your health include air & water quality, poisonous wastes in landfills, & exposure to solar radiation

44. Air Quality • Carbon monoxide is found in automobile exhaust & cigarette smoke • When carbon monoxide is inhaled, it prevents hemoglobin from carrying oxygen

45. Air Quality • Lead is a particulate found in the air that can poison the liver, kidneys, & nervous system • Lead poisoning in babies & young children can result in slow mental development

46. Air Quality • Asbestos is another particulate that may be carried in the air • It was commonly used for insulation, & when inhaled, it can cause lung cancer

47. Water Quality • Water can carry biological & chemical pollutants • Biological pollutants, like human & animal wastes, can contain bacteria or viruses that cause cramps, vomiting, diarrhea, or diseases like hepatitis or cholera

48. Water Quality • Some chemical pollutants cause organ damage • Others interfere with development of organs & tissues, causing birth defects • Still others can damage DNA, causing normal cells to become cancerous

49. Bioterrorism • Bioterrorism involves treating pathogens to maximize their ability to infect & cause disease • Anthrax is a disease common in cattle-ranching areas, not life-threatening • The spores can be treated to be spread in the air & inhaled, producing a fatal infection

50. Cancer • Cancer is a life-threatening disease where cells multiply uncontrollably & destroy healthy tissue • Cancer cells are the bodies own cells