1. Ch. 40 The Immune System & Disease
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

51. Cancer
Cancer begins when cells grow & reproduce uncontrollably, resulting in a tumor
Tumor - the formation of a mass of growing tissue

52. Cancer Benign tumors are NOT cancerous
Malignant tumors are cancerous, & are capable of invading & destroying surrounding healthy tissue

53. Cancer
Cancers are caused by defects in the genes that regulate cell growth & division
The genetic defects may be inherited, caused by viruses, or result from mutations in DNA that are produced by chemicals, radiation, or occur spontaneously

54. Cancer
Carcinogens - chemical compounds that are known to cause cancer by triggering mutations in the DNA of normal cells
Some of the most powerful chemical carcinogens are found in tobacco smoke

55. Cancer
The best way to fight cancer is by protecting your DNA from agents that cause cancer
Regular exercise & a balanced diet, regular checkups, self-examinations, etc., can all help reduce your risk

56. Maintaining Health
To keep your immune system working efficiently, practice behaviors that reduce your exposure to pathogens & maintain overall good health
Healthful behaviors include eating a healthy diet, exercise, get plenty of rest, abstaining from harmful activities, & have regular checkups