1. The Body’s Defense System
Chapter 31
The Body’s Defense System
Poke me!

2. The Germ Theory of Disease
Diseases are spread from one organism to another, by microscopic particles

3. Pathogen
Any disease causing organism or virus
(Ex.) bacteria, fungi, virus, protists

4. Infectious diseases
Are caused by pathogens and can be transmitted to other healthy organisms

5. Transmission of Infectious Diseases
Airborne
Physical contact
Contaminated food or H2O
Sexual contact
Animals (ex. Lyme disease)

6. The human body
has three lines
of defense
against infections

7. The First Line: Barriers
Physical & chemical non-specific defenses, (that means they prevent many different diseases from infecting us)

8. Examples: Skin, Hair Mucous membranes Saliva Stomach acid & enzymes
Sweat, tears

9. The Second Line: Internal Nonspecific Defenses
3 types:
White blood cells
Inflammatory response
Specialized proteins

10. remove any foreign materials, by phagocytosis
White Blood Cells
Macrophages & neutrophils
remove any foreign materials, by phagocytosis

11. Macrophage and E. coli pink = macrophage
yellow = bacteria; note rod-like structure of bacillus

12. macrophage after a bacterium (pathogen)

13. White Blood Cells
Natural killer cells kill our cells infected with a pathogen, thus killing the pathogens too.

14. The inflammatory Response is recognized by:
Redness, heat, swelling, pain
Histamine causes blood vessels to dilate (expand)
That increases blood supply

15. Specialized Proteins
Produced by cells
Ex. Interferon
Help remove pathogens

16. The Third Line: Targeted Defense
Specifically target a single disease
Immune system can recognizes our cells(“self”) vs. (“non-self”) cells

17. 3rd Line the IMMUNE RESPONSE
If a pathogen gets by the 2nd line of defense:
Cells are programmed to attack and destroy

18. Antigens & Antibodies
Antigen: proteins on ‘nonself’ cells that begin an immune response

20. Antibodies
proteins produced by our immune systems to remove specific pathogens.

23. Lymphocytes WBCs that are designed to remove SPECIFIC invaders
2 types: B cells & T cells

24. B Cells
Develop in Bone marrow
Produce antibodies

26. Cytotoxic T cells Mature in the Thymus
Destroy host cells infected with a pathogen.

27. Helper T cells Attach to antigen displayed on a WBC
Program cytotoxic T cells and B cells to destroy that pathogen

29. Memory Cells
Both type B & T lymphocytes produce memory cells to respond more quickly to the same pathogen

30. The Third Line of Defense
The Immune Response
The Third Line of Defense

31. A Summary of
the Immune
Response

32. 1. Macrophage (WBC) ingests pathogen (phagocytosis)
2. Pathogen is digested, antigen is displayed

33. 3. WBC shows the antigens
4. Helper T cells bind to antigens

35. 5. Helper T cells activate T cells and T memory cells

36. Chemical Secretion Memory T cells Helper T cells activate
TC & TM cells
Chemical
Secretion
TC cells destroy
pathogen
Memory
T cells

37. Next, B cells are activated (programmed)
B cells multiply
Memory B cells are made
B ‘s become Plasma B cells & secrete…
Antibodies (destroy pathogen)

38. ABO Blood Groups
Blood typing is determined by the antigens present on the surface of the RBCs.
There are A & B antigens

39. This results in Four possible blood types:
Blood Groups
This results in Four possible blood types:
A, B, AB, O

40. BLOOD TYPE A

41. BLOOD TYPE B

42. BLOOD TYPE AB

43. BLOOD TYPE O

45. A B AB O BLOOD TYPE A B A & B neither A nor B Blood Type
RBC Antigens Present
Blood Type A B
A & B
neither A nor B A B AB O

46. Antibodies Present in Plasma
BLOOD TYPE
Blood Type
Antibodies Present in Plasma A B AB O B A
None
A & B

47. A O B O A B AB O O A B AB O BLOOD TYPE Blood Type Universal Recipient
Can Receive Type: A B AB O A O B O A B AB O O
Universal Recipient

48. A AB B AB AB A B AB O A B AB O BLOOD TYPE Blood Type Universal Donor
Can Donate To: A B AB O A AB B AB
Universal
Donor AB A B AB O

49. Blood Typing Game

50. Plasma Donations
In an emergency situation plasma may be transfused instead of blood cells. Why??
No typing is necessary!

51. Organ Transplants
Possible rejection because body is recognizing “self” versus “non-self” tissues
Medications suppress immune system to decrease rejection  but lowers defense system against other infections

52. Vaccines
stimulate the
immune response

53. Vaccine development Edward Jenner
1796, used cowpox to provide immunity to small pox
Louis Pasteur
1885, developed vaccines for rabies & anthrax
Jonas Salk/Albert Sabin
1955, Salk developed injectable vaccine for polio
1961, Sabin developed an oral vaccine
The term vaccine comes from vaccinus, Latin for “from cow”. Jenner was an English doctor who noticed that milkmaids who were exposed to cowpox didn’t contract the more virulent disease of small pox. Jenner injected a milkmaid that had not contracted cowpox with that pathogen. The milkmaid developed immunity to smallpox.
Pasteur studied anthrax, a fatal disease of cattle, and developed a weakened or attenuated form of the bacteria that causes the disease. He inoculated 25 sheep with the vaccine and then inoculated this group and an additional 25 sheep with the anthrax bacillus several days later. The 25 sheep that had not been vaccinated died, while the vaccinated sheep were protected. He also worked on developing a vaccine for rabies and performed the first successful test on a young boy whose mother pleaded with Pasteur to treat her son after the boy had been bitten by a rabid dog. The boy underwent treatment with vaccinations for 10 days and recovered completely.
Polio is a disease of the central nervous system, specifically the spinal cord and is caused by a virus. Previously, the greatest incidence of the disease was in children between the ages of 5 and 10. There were over 57,000 cases of polio diagnosed in Because we have an effective polio vaccine, very few cases of the disease are diagnosed each year. The first vaccine was developed by Jonas Salk. The Sabin oral polio vaccine is the type most commonly administered in the U.S.
Koch’s Postulates are still used as the standard protocol today to prove that a pathogen causes a specific disease. A diagram of the process can be found on the next slide, entitled “Vaccine development uses Koch’s Postulates”.

54. Vaccines
Dose of a pathogen or part of a pathogen that is disabled or destroyed  no longer harmful

55. Vaccines Different types: Use just antigens of pathogen
Grind or heat pathogen so it can’t function
Similar version of pathogen
Booster shots

56. Stages in
Vaccine-Induced
Immunity

57. Active Immunity
When your body produces antibodies against an infection

58. Active Immunity
2 examples:
Previous infection
Vaccines

59. Passive Immunity
When you receive antibodies from another source

60. Passive Immunity Examples: Fetus from mother
Traveling  antibodies temporarily protect

61. Disorders of the immune system are major health problems
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