Animal Defense Mechanisms… Immunity

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

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

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

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!

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

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)

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