1. Chapter 4343.1Pgs. 929-935 This is challenging material!!! *Don’t think black & white: There are always exceptions… Objective: I can describe the basic categories and classifications of the immune system.

2.  Innate Immunity Present since birth Rapid Response to microbes Has non-specific broad range  Divided into External and Internal  Adaptive Immunity (a.k.a. Acquired) Develops only after exposure Slower Response to microbes Has very specific targets  Divided into Humoral (Antibodies) and Cell-Mediated (Cells) Responses

3.  Skin – most external barrier Dry (hard for microbes to live on) Acidic (pH: 3~5) from oil/sweat glands Secretes lysozyme (more in a bit)  Mucous Membranes – internally external Mucus – thick liquid to trap microbes  Cilia can sweep out to remove Can be acidic (stomach membrane) Secretes lysozyme  Lysozyme = antimicrobial proteins – designed to digest cell wall of bacteria http://www.youtube.com/watch?v=by6DKnvl5nE http://www.youtube.com/watch?v=miEEluVlemQ

4.  Four main categories (will cover 3 in detail) 1) Phagocytic Cells  Cells that do phagocytosis – several types 2) Inflammatory Response  Swelling, heat, etc. 3) Antimicrobial Proteins  Secreted by infected cells and others 4) Natural Killer (NK) Cells  Attack virus-infected cells & cancer cells  Release chemicals to trigger apoptosis  Mechanisms not fully understood http://www.youtube.com/watch?v=HNP1EAYLhOs

5.  Types of WBCs (Leukocytes) Neutrophils (vast majority of WBCs)  Engulf cells and die (self-destruct) Macrophages  Monocytes  Larger and more complex (changing) Eosinophils & Dendritic Cells (other…)  All recognize broad shapes using TLR: Toll-like receptor

7.  Platelets (thrombocytes)  Erythrocytes (RBCs)  Leukocytes (WBCs) Phagocytic Cells (4 types) Lymphocytes (adaptive immunity)  Basophils  Inflammatory Response

8.  (Painful) swelling and heat caused by Vasodilation: increased blood flow due to Mast cells (type of Basophil) releasing histamine: triggered by injury/invasion  Purpose: to bring in phagocytes, which will consume & release MORE chemicals… http://www.youtube.com/watch?v=uNG-jZxvhcg

9.  Cytokines/Chemokines: attract/produced by phagocytes ( positive feedback ) and other cells  Septic shock: systemic inflammation Swelling is good AND bad…(entire body) http://www.youtube.com/watch?v=CmbWE3jLUgM

10.  Attack microbes or impede reproduction  Set of ~30 proteins  Complement System Surface substances on microbes trigger a cascade (signal pathway – Ch. 11)  Leads to lysis of bacteria, but can also trigger inflammation and acquired imm.  Interferon: protein secreted by virus- infected cell, so neighboring cells not infected (limit spread of viruses)  Defensins: secreted by macrophages http://www.youtube.com/watch?v=vbWYz9XDtLw

11.  System to recollect interstitial fluid Also ends up collecting and entrapping pathogens that made it to the circulatory system Lymph Nodes are like junction points, with large amounts of pathogens collected; WBCs collect there to kill

12.  Contain many innate immune structures similar to vertebrates Exoskeleton ≈ Skin External Defense Hemocytes in Hemolymph ≈ Phagocytes  No inflammatory or lymphatic system…  Lack adaptive/acquired immunity No Immunological Memory

13.  Pathogens evolve ways to survive Some bacteria resist breakdown in lysosomes after phagocytosis Need for adaptive immunity, but… Evolution “Arms Race” http://www.youtube.com/watch?v=G7rQuFZxVQQ