1. Chapter 11 – Elements of Host Protective Responses
Medical Microbiology
Chapter 11 – Elements of Host Protective Responses

2. Our Defense Systems
Our body has 3 layers/walls of defense against pathogens and toxins
1st = barriers
2nd = innate responses
3rd = antigen-specific immune responses
My Analogy

3. Barriers Barriers Skin Mucous membranes Secretions Normal flora
lactic acid and fatty acids (skin)
mucus: filter for respiratory system, etc.
Tears, lysozyme, stomach acid
Normal flora

4. Innate Responses
Innate Responses – they are always present and ready to go.
Complement Proteins
Neutrophils and Macrophages
Natural Killer cells

5. Ag-specific Responses
Must be produced after infection (usually takes 5-7 days)
Activated B-cells produce Antibodies
Activated T-cells attack and destroy infected cells and cancer cells

6. Players in Defense
Chemicals (allow communication between cells):
Cytokines – stimulate and regulate the immune response
Interferons – anti-viral proteins, stimulate immune response
Chemokines – involved with the inflammatory response
They lead to chemotaxis and activation

7. Players in Defense Table 11-1 Cells (carry out the actual defense):
Table 11-2 and Figure 11-1
Some are designated by CD “Clusters of Differentiation”
MHC I – found on all nucleated cells
MHC II – found on antigen-presenting cells (APCs)

8. Players in Defense
Blood cells of defense – Table 11-3

9. The Lymphatic System Functions:
Return tissue fluid to the blood stream
Why is this necessary?
Example (~30L out of capillaries, 27L in)
Fat transportation
Immunity – defense against pathogens and other foreign material

10. Lymphatic Vessels Lymph capillaries – pick up interstitial fluid
Lymph vessels – have one-way valves like the veins
Lymph is dumped back into the blood
Figures from other text

16. Lymphatic Vessels
As the lymph travels back to the blood stream it passes through many lymph nodes
Figures

19. Lymph Nodes Function as filtering stations for the lymph
Macrophages are in the lymph nodes
What do they do?
B-cells and T-cells are also in the lymph nodes
Swollen lymph nodes

20. 4

21. Lymph Nodules and Tonsils
No lymph filtering
Tonsils are accumulations of lymph nodules
Function?
swollen tonsils are a sign of a throat infection
Figure

22. 3

23. Spleen
The spleen is the filtering site for the blood
Dead RBCs
Figure

24. 6