1. Immunity
Chapter 40

2. The nature of disease

3. Infectious diseases
Any disease caused by the presence of pathogens in the body

4. Pathogens Disease-causing agents
Bacteria, protozoans, viruses, fungi, parasites

5. Sources  soil, water, food, infected animals

6. Determining cause of a disease
Some are caused by pathogens 50%
Inherited
Aging

7. Robert Koch Identified the first pathogen in 1876
Anthrax bacterium from cattle

8. The spread of infectious disease
Must be able to survive
People
Animals
Water and food
Soil

9. Direct contact
Passed directly from person to person
STDs

10. Indirect contact
Passed through objects like doorknobs
The common cold

11. Through a vector  animals or objects
Malaria  mosquito
Lyme disease  deer tick

12. Airborne
Passed through the air as droplets
Colds, the flu, SARS

13. Symptoms of disease Caused by a disruption of homeostasis
Pathogen multiplies, damaging tissues
Viruses  take over cells
Bacteria  production of toxins
Fever, destruction of blood cells or vessels, inhibit protein synthesis, disrupt the nervous system

14. Patterns of disease

15. Endemic
Constantly present in a population
The common cold

16. Epidemic
Many people in an area afflicted with the same disease at the same time
Influenza

17. Pandemic
People worldwide are afflicted with the same disease
HIV

18. Treating diseases
Antibiotics  substances produced by 1 microorganism to kill or inhibit the growth of another microorganism
Not effective against viruses
Problem  bacterial resistance

19. Defense against infectious diseases

20. Body’s earliest lines of defense
Innate immunity
Body’s earliest lines of defense

21. Skin
Physical barrier

22. Body secretions Mucous  traps invaders
Sweat, tears, saliva all contain enzymes to break down cell walls of some bacteria
HCl in stomach also breaks down cell walls

23. Inflammation of body tissues
Redness  more RBCs
Release of histamine by WBCs and injured cells
Swelling, pain, heat  fluid leaks from vessels into injured tissue

24. Steps of the inflammatory response

25. Phagocytosis of pathogens  microorganisms
3 types of phagocytes
Monocytes  small, immature macrophages
Macrophages  engulf and digest pathogens
Phagocytosis

26. Phagocytosis continued
Neutrophils  engulf and digest
Pus  dead macrophages and body fluids

27. Interferons Proteins that protect against viruses
Produced by infected body cells
Diffuse into environment  inhibits viral multiplication

28. Acquired immunity
Defending against a pathogen by gradually building up resistance
Works with innate immunity

29. Acquired continued Antigens  non-self
Antibodies  produced in response
Can take days or weeks
Antibody and cellular immunity

31. Cellular immunity
T cells  produced in bone marrow and matured in thymus gland
Cytotoxic (killer) T cells  produce enzymes which lyse bacteria
Helper T cells  activate killers
Suppressor T cells  stop attack

32. T cell mechanism of action

33. Antibody immunity B cells  produced and matured in bone marrow
Activated by helper T cells
B cell divides into:
Plasma cell  antibodies
Memory B cell
Complement system  enzymes to help fight bacteria

34. B cell mechanism of action

35. Passive immunity Antibodies from an outside source
Natural  maternal immunity
Artificial  injections from animal or other human

36. Active immunity Body produces antibodies and killer T cells
Natural  having the disease once
Secondary immune response is faster

37. Active continued Artificial  vaccines
Attenuated  using weakened microbes for exposure
Edward Jenner  1st safe vaccine for cowpox

38. Lymphatic system Defense and homeostasis
Lymph  collected tissue fluid
Lymph capillaries and veins parallel to circulatory vessels
Lymph flows toward the heart
Returns to bloodstream through ducts in the shoulder area

39. Lymphatic system cont.
Lymph nodes  bean-shaped glands that filter pathogens from lymph
Tonsils, neck, armpits, groin
Produce lymphocytes (WBCs)

40. Lymphatic system cont. Spleen  stores lymphocytes
Filters and destroys bacteria and old RBCs
Thymus  lymphocytes are matured

41. The lymphatic system

42. Immune System Disorders

43. HIV  human immunodeficiency virus
Attaches to receptor on helper T cells
Other cells cannot be activated
RNA turned to viral DNA
Incubation period  4-10 years
Death caused by inability to combat other pathogens

44. HIV life cycle

45. Allergies Overreaction to an antigen
Release of histamine  inflammatory response
Antihistamines block action
Common allergens  pollen, food, dust, animal hair

46. Autoimmune diseases Produce antibodies against self
Rheumatoid arthritis  cartilage in joints
Multiple sclerosis  motor responses

47. Autoimmune continued Lupus erythematosis  against DNA
SCID  severe combined immunodeficiency

48. Cancer  uncontrolled cell replication
Caused by mutations in DNA  viruses, chemicals, radiation, genetic predisposition
Sarcoma  connective tissue, bone, muscle
Carcinoma  epithelial tissue (skin, organs)
3 deadliest forms  lung, colo-rectal, breast