1. Anatomy & Physiology II
Unit Ten

2. Body Defenses
The immune system protects the body from invasion by pathogens (infectious microbes, toxins & radiation)
The human immune system is comprised of two types of defenses:
> nonspecific
> specific

3. Nonspecific Body Defenses
Nonspecific defenses are those that react the same no matter the pathogen that is attempting to invade the body
These nonspecific defenses are the first line of defense against invasion

4. Nonspecific Body Defenses
The five types of nonspecific defenses:
> barriers
> phagocytes
> fever
> interferons
> inflammatory response

5. Nonspecific Body Defenses
Barriers such as the skin and mucous membranes prevent pathogens from gaining access to the body
These barriers also secrete a number of enzymes that can destroy or inhibit the growth of microbes

6. Nonspecific Body Defenses
Phagocytes are the different types of WBCs and macrophages that are found in the lymphatic system, blood and body tissues that consume any pathogens or foreign materials

7. Nonspecific Body Defenses
Fever (pyrexia) is the elevation of body temperature so as to cause the liver & spleen to hoard zinc & iron, depriving bacteria of minerals needed to reproduce
Temperature elevation is due to the release of interleukin by active neutrophils and macrophages

8. Nonspecific Body Defenses
Interferons are proteins secreted by cells that have been infected by viruses
These proteins alert surrounding cells so they can prevent infection and activate macrophages to destroy already infected cells

9. Nonspecific Body Defenses
The inflammatory response is a localized reaction to injury, trauma or infection
Its primary functions are:
> contain the spread of pathogens
and destroy them
> clean up tissue damage & debris
> promote tissue repair

10. Nonspecific Body Defenses

11. Specific Body Defenses
Specific defenses involve immunity which can be cellular or humoral and memory
Immunity is directed against a specific pathogen and the memory component recognizes the pathogen if it is reintroduced

12. Specific Body Defenses
Lymphocytes are the backbone of immunity and there are two types
- T lymphocytes & B lymphocytes
T lymphocytes (T cells) are active in cellular immunity, attacking pathogens and infected cells directly

13. Specific Body Defenses
B lymphocytes (B cells) are active in humoral immunity, using antibodies to render pathogens inactive or by clumping the pathogens so they are not active and phagocytes will then consume them

14. Specific Body Defenses

15. Specific Body Defenses

16. Primary Immune Response Secondary Immune Response
Specific Body Defenses
Primary Immune Response
Secondary Immune Response

17. Specific Body Defenses
Active humoral immunity occurs when B cells encounter antigens and begin producing antibodies
This immunity can be acquired by infection or vaccination and is very powerful in that it invokes the secondary immune response

18. Specific Body Defenses
Passive humoral immunity occurs when antibodies are transferred to the blood
Antibodies are transferred from mother to fetus or artificially through injections
B cells are not activated so immunity is temporary

19. Specific Body Defenses
Immunoglobulin (antibodies) are produced by B cells during humoral response
There are five major classes of immunoglobulins based on the location of their protein chains

20. Specific Body Defenses
Immunoglobulin classes:
•IgM – pentamer in shape
•IgA – dimer in shape
•IgD – monomer in shape
•IgG – monomer in shape
•IgE – monomer in shape

21. Infectious Agents
Bacteria cause stress (sickness) by producing toxins that may damage or destroy cells
Bacterial infections are treated postsymptomaticaly with antibiotics

22. Infectious Agents
Viruses cause stress (sickness) by injecting their nucleic acid into a cell, which will then use the resources of the cell to replicate more viruses
After filling with new viruses, the cell will lyse and be destroyed

23. Infectious Agents
Viral diseases are treated presymptomaticaly with vaccines
Once a viral infection has occurred, the symptoms must run their course

24. Infectious Agents
Human immunodeficiency virus (HIV) infects and destroys helper T cells
Without helper T cells the entire immune response shuts down, rendering the individual defenseless against infection