1. Animal Defense Mechanisms… Immunity

2. Non Specific Defense (Innate Immunity)
Protects against microbial attacks
- dust
- pollen
- bacteria

3. Includes… PHYSICAL BARRIERS - Skin and mucus membranes
CHEMICAL BARRIERS
- Lysozymes
- Gastric acids
- Interferons
- Complement system
*more on these later!

4. CELLULAR BARRIERS
- Macrophages
- Neutrophils
- Natural Killers cells
Also includes the INFLAMMATORY RESPONSE
- Histamine release  Increased blood flow to area
- Attraction of phagocytes
- Sometimes a fever

5. Definitions… Lysozyme:
- Enzymes that act to damage/destroy bacterial cell walls
Interferons:
- Signaling proteins  released in response to pathogens
- Triggers defense; also called CYTOKINES
Complement System:
- Enhances ability of antibodies and phagocytes to clear away microbial agents
- Part of Innate system BUT can be recruited by the Adaptive system too!

6. Specific Defense (Adaptive/Acquired Immunity)
Protects against specific foreign invaders (antigens or pathogens)
There are FOUR ways this can be done:
Active
- produce antibodies
- can be initiated through vaccines

7. Passive
- Antibodies supplied to fetus via placenta or through milk to baby
Humoral
- Antibodies in blood & lymph that defend against bacteria & viruses
Ex. B cells
Cell-Mediated - Specialized lymphocytes… will react against viruses & bacteria but also protists, worms, cancerous cells, etc
Ex. Helper T cells (Th), Cytotoxic T cells (Tc)

9. Specificity of Immune Response
Already have antibodies in memory  produce millions of antibodies very quickly
“B” is a different antigen
First exposure