1. Immune System Phagocytes Killer T-cells Macrophages
Natural Killer Cells

2. Immune system Function = destroy & remove all “non-self”
(pathogens/invaders)
Often considered part of the Circulatory System
2 Types of Body defenses =
1. Non-specific
2. Specific

3. I. Non-Specific Body Defenses
Effective against all infections
First line of defense – Skin
1. Physical barrier
prevents entry of pathogens
(micro-organisms)
2. Must be unbroken to be effective
3. Skin is acidic, plus oil & sweat glands
inhibit bacterial growth

4. Non-Specific Body Defenses
B. Mucus Membranes
1. Location:
respiratory, digestive,
urinary,
& reproductive tracts
2. F(x) = trap pathogens & debris

5. Non-Specific Body Defenses
C. Hairs (nasal passages)
F(x) = trap pathogens & debris
Nose hairs

6. Non-Specific Body Defenses
D. Cilia
- throat
(upper respiratory tract)
- trap pathogens & debris

7. Non-Specific Body Defenses
E. Cellular & Chemical defenses
Activated when
outer defenses
are breached

8. 1. Phagocytes
a. Cells that recognize “non-self”, i.e. foreign particles or invaders
Phagocyte eating dying cells

9. 1. Phagocytes
b. E.g. White Blood Cells (WBCs) such as neutrophils & macrophages
c. Travel to infection site via circulatory system (bloodstream) or lymphatic system
d. Can squeeze through intercellular spaces

10. 1. Phagocytes d. Engulf (“eat”) invaders / foreign debris
e. Release lysosomes to dissolve invaders / foreign debris
Phagocytes & yersinia pestis

11. 2. Natural Killer Cells (NK cells)
a. WBCs – police the blood
& lymph
b. Bind to membrane of invader,
release chemicals,
lyse cell

12. 3. Inflammatory Response
a. Inflammation = heat, redness, swelling due to fluid build-up, pain
b. Localized response at site of tissue damage
c. Prevents spread of damaging agent

13. Inflammatory Response

14. Inflammatory Response

15. 4. Fever a. Systemic response to infection
b. Stimulates phagocytes (WBCs) to work
c. Heat kills many pathogens

16. 5. Interferon a. Secreted by virus-infected cells
b. Stimulates non-infected cells to make proteins that block viral protein synthesis
c. Slows infection to allow specific defenses to begin working
d. Activates macrophages to “eat” (non-self)
viral invaders

17. II Specific Body Defenses (against a specific pathogen)
General Information
Create Immunity = highly specific resistance to disease
Particular invader recognized, switches on immune response
Specific Invader is remembered so that future invasions can be immediately fought

18. II Specific Body Defenses
B. Antigen
1. Irritant or pathogen
2. Stimulates formation of antibody

19. C. Antibody i.e. Bone marrow  makes B-cells, which make specific
1. Forms due to exposure to a specific antigen
2. Produced by B-cells
i.e. Bone marrow  makes B-cells, which make specific
antibodies
3. Binds to antigen to mark it for
destruction by
macrophages

20. C. Antibody 4. Found in plasma & all body secretions
5. Once present, allows immediate immune response to pathogens
6. (memory B cells remember pathogen, so next exposure brings rapid response)

21. Antigen Antibody Response
Antibodies
Antigens

22. D. Macrophages
- destroy cells marked by antigen-antibody complex

23. E. Helper T-cells Activate other T-cells Attract Killer T cells
& macrophages to an
antigen

24. F. Killer T-cells
– directly attack & kill pathogens, release cytotoxic chemicals to lyse cells

25. G. Suppressor T-cells
- stop immune response when antigen is successfully overcome

26. Notice ! Non-specific and Specific Defenses work together
to protect the body
from disease-producing pathogens

27. Origins of cells B cells mature in bone tissue
T cells mature in thymus tissue

28. Types of Immunity (3) long-lasting)
1. Active – vaccinated against or recovered from the disease (immunity permanent or
long-lasting)

29. Types of Immunity (3) 2. Passive – antibodies
produced by another organism injected into body
(temporary protection
against the disease)

30. Types of Immunity (3)
3. Cell Mediated – killer T-cells attack any cell not marked with a special protein
(i.e. cells that are “non-self”)

31. Cell-mediated Immunity

32. Immune system Vaccine= living or inactivated organism
used to induce specific immunity
Can be made from antibodies, or cause antibodies to be made
Immunization= process that increases an organism’s rxn to antigen & therefore improves its ability to resist or overcome infection