This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: 18 Natural Defenses against Disease 18 Animal Defense Systems Humans are nutritious and taste good ! ... to pathogens ! Possible pathogens: viruses bacteria single-cell eukaryotic parasites (yeast) parasitic worms maggots lions? (usually not considered pathogens) The immune system is a set of mechanisms that protect an organism from infection by identifying and killing pathogens. Decaying mole: 40 hours compressed to 30 sec http://www.youtube.com/watch?v=cb7wBQIR2_0 What happens in the absence of an immune system? 18 Animal Defense Systems ! The immune system must be absolutely specifc and not attack normal cells and tissues. ! Pathogens are constantly evolving new ways to avoid detection by the immune system: the immune system must be adaptive . ! The immune system must recognize and defeat pathogens: " viruses " bacteria " single-cell eukaryotic parasites fungi (yeast) " parasitic worms " maggots 18 Animal Defense Systems There are two general types of defense mechanisms: ! Nonspecific defenses, or innate defenses, are inherited mechanisms that protect the body from many different pathogens: The Innate Immune System ! Specific defenses are adaptive mechanisms that protect against specific targets: The Adaptive Immune System Innate immune system Adaptive immune system Response is non-specifc Pathogen and antigen specifc response Exposure leads to immediate maximal response Lag time between exposure and maximal response Cell-mediated and humoral components Cell-mediated and humoral components No immunological memory Exposure leads to immunological memory Found in nearly all orms o lie Found only in jawed vertebrates 18 Who are the players? 18 The players Components of the defense system are distributed throughout the body. Lymphoid tissues (thymus, bone marrow, spleen, lymph nodes) are essential parts of the defense system. ! Blood (closed circulatory system): suspends red and white blood cells and platelets. " Red blood cells are found in the closed circulatory system. " White blood cells and platelets are found in the closed circulatory system and in the lymphatic system. 18 Animal Defense Systems There are two general types of defense mechanisms: ! Nonspecific defenses, or innate defenses, are inherited mechanisms that protect the body from many different pathogens: The Innate Immune System ! Specific defenses are adaptive mechanisms that protect against specific targets: The Adaptive Immune System...
View Full Document
- Spring '08