1. DION KEVIN LUKE LEARY RACHAEL-CATHERINE HARTNETT The Immune System Concept 43.1- In innate immunity, recognition and response rely on shared traits of pathogens

2. Introductory Video http://www.cleanvideosearch.com/media/action/yt/ watch?v=Nw27_jMWw10 http://www.cleanvideosearch.com/media/action/yt/ watch?v=Nw27_jMWw10

3. Overview Pathogens- infectious agents that cause disease  Ex: viruses, bacteria, protists, and fungi Immune system- the defenses which enable an animal to avoid or limit many infections Innate immunity- the immediate and undifferentiated immune response in animals Acquired immunity- immune responses which are specific to pathogens which have already been introduced

5. Innate immunity of Invertebrates Insects rely on the chitin in their exoskeletons as well as in their intestines for the first line of defense Lysozyme, an enzyme that digests microbial cell walls, as well as low pH in digestive system aid in the first line of defense Hemocytes, immune cells in insect blood (hemolymph), carry out phagocytosis Other hemocytes stimulate chemical production and antimicrobrial peptide production

6. Phagocytosis

7. Innate Immunity of Invertebrates cont. Antimicrobial peptides circulate and disrupt the membranes of fungi and bacteria Immune response cells rely on identification of unique molecules on invader surface layers Ex: pg 932

8. Innate Immunity of Vertebrates Barrier defenses-Barrier defenses are the typical front line against pathogens. Skin, Mucous membranes, tears, etc. Beyond the role of blocking pathogens from the body many create a pathogen killing environment for toxins.

9. Innate Immunity Cont. Cellular Innate defenses 1. Toll-like receptors-recognizes molecule fragments of pathogens 2. Neutrophils- phagocytic cells which engulf pathogens 3. Macrophages- Large phagocytic cells which engulf pathogens efficiently. Most common in lymphatic organs 4. Eosinophils-fight multiple cell invaders such as parasites. Release enzymes to kill invaders 5. Dendritic Cells-stimulate tissues to develop an acquired immunity

10. Innate immunity cont. Peptides and proteins work to fight and destroy pathogens. The body fights pathogens in many other ways such as through inflammation Natural Killer cells.

11. Innate Immune System Evasion by Pathogens Several pathogens have developed certain mechanisms that allow them to avoid destruction by pathogenic cells. In order to do this, for example, the outer capsule that surrounds the bacteria hides the polysaccharides of their cell walls, which prevents recognition. However, for bacteria that are unable to avoid recognition, some develop resistanceto breakdown by lysosomes. An example of this is Tuberculosis(TB). Instead of being destroyed, microbes grow and reproduce, hidden from immune defenses of the body.