VPHY 3100: Week of 10/5/15
VPHY 3100: Week of 10/5/15 VPHY 3100
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This 4 page Class Notes was uploaded by Lorin Crear on Friday October 9, 2015. The Class Notes belongs to VPHY 3100 at University of Georgia taught by Dr. Li, Dr. Wells, Dr. Brown in Summer 2015. Since its upload, it has received 62 views. For similar materials see Elements of Physiology in Animal Science and Zoology at University of Georgia.
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Date Created: 10/09/15
Chapter 15 The Immune System 0 The Immune System 0 Protects against pathogens diseasecausing agents 0 Two divisions I Innate defense 0 Inherited from mother to baby 0 Nonspecific 0 First line of defense I Adaptive defense 0 Developschanges as a result of exposure 0 Specific responses to different pathogens 0 Innate Immune System I Defense Mechanisms 0 External Defense 0 Skin 0 Epithelial barriers I Digestive tract 0 HCl and enzymes in stomach I Respiratory tract 0 Mucus cilia and enzymes I Genitourinary tract 0 Acidic environment I Tears and saliva o Antibacterial enzymes 0 Internal Defense 0 Fever 0 Interferons o Phagocytes I Activation 0 Triggered by pathogenassociated molecular patterns PAMPs o All pathogens express PAMPs I Lipopolysaccharide LPS in Gram bacteria I Peptidoglycan in Gram bacteria 0 Gram refers to absencepresence of cell wall respectively 0 PAMPs recognized by surface tolllike receptors TLRs of macrophages monocytes or lymphocytes I Lymphocytes killer T cells natural killer cells and plasma cells 1PAMP binds to TLR forming PAMPTLR complex 2Complex formation stimulates release of cytokines from immune cell a Cytokines signaling proteins 3Cytokines activate other immune cells 4Usually in ammation occurs I In ammation I Phagocytosis oewwe Different subtypes of TLRs bind to different PAMPs Normal part of healing process Characteristics 0 Redness o Swelling and pus depending on type of bacteria causing in ammation 0 Warmth 0 Pain Initiates nonspecific phagocytosis by White blood cells WBCs Initiation 1 Injuredinfected tissues release cytokines 2 Cytokines activate mast cells nearby 3 Mast cells secrete cytokines histamine TNFor prostaglandins and leukotrienes 4 Histamine causes vasodilation 5 Vasodilation makes it easier for WBCs to reach injuredinfected tissues I WBCs also attracted by DAMPs 0 Dangerassociated molecular patterns 0 Released before death necrosis by injured cell 0 Cells that die from apoptosis programmed cell death do not release DAMPs 6 Diapedesis I Histamine also causes pores in membrane of blood vessel to Widen increasing permeability I Monocytes arrive and perform diapedesis exiting of capillaries also called extravasation through pseudopod movement 7 Monocyte transforms into macrophage 8 Macrophages perform phagocytosis Release of too much histamine can cause constriction of bronchi amp bronchioles 9 asthma Red blood cells RBCs do not perform diapedesis because their structures are too rigid to allow pseudopod movement Degradation of injured cells or bacteria Phagocyte engulfs bacterium in a vacuole Vacuole fuses With lysosomes organelle containing enzymes Formation of phagolysosome Enzymes destroy bacteria Types of phagocytes o Neutrophils I First to arrive at site of information I Remains constitute large portion of pus o Monocytes I Second to arrive I Become macrophages I May serve as antigenpresenting cells to lymphocytes 0 Tlymphocytes I Third to arrive I Part of specific immunity neutrophils and monocytes are innate I Fever 0 Caused by hypothalamus o Induced by 0 Exogenous pyrogens such as LPS I From pathogens 0 Endogenous pyrogens I Includes interleukins IL and or other cytokines 0 IL also called lymphokines are subset of cytokines 0 Secreted specifically by lymphocytes to communicate With other lymphocytes I Released by WBCs I Release stimulated by exogenous pyrogens 0 Effects 0 Increases activity of neutrophils o Increases interferon production I Interferons 0 1 B Y subtypes 0 polypeptides produced by cell infected With virus 0 provide shortacting nonspecific resistance to viral infection in nearby cells 0 increase overall immune activities 0 decrease tumor growth 0 Decreases bacterial activity 0 Adaptive Immune System I Antigens Ag 0 Molecules that elicit production of antibody Ab 0 One type of Ab recognizes specific Ag 0 Usually large molecules foreign to body 0 Specific responses to each antigen 0 Humoral immunity responses related to transport of Ab produced by B cells in body uids 0 Cellmediated immunity responses related to direct contact of T cells With pathogens I B lymphocytes B cells 0 Include memory cells and plasma cells 0 Have Ab receptors for specific Ag binding 0 AgAb binding I Causes B cell to clone 0 Some clones become memory cells long lifetime 0 Some become plasma cells Ab factory 0 Memory cells direct plasma cells to produce Ab 0 Antibodies o Immunoglobulin proteins hence Ig prefiX 0 Structure I Y shape I 2 long heavy H chains and 2 short light L chains I Each chain contains constant fragment PC and variable fragment Fab I Fab is responsible for Ab specificity I IgG main Ab in circulation I IgA main Ab in mucus secretions I IgE responsible for allergic reactions I T lymphocytes T cells 0 Originate in thymus 0 Account for 65 85 of blood lymphocytes 0 Killer cytotoxic T cells 0 Kills pathogens by coming into contact With Victim I Secretion of perforins 9 create pore in Victim s membrane 9 Victim s cytosol and organelles escape through pore I Secretion of granzymes 9 destroy Victim s DNA 0 Helper T cells 0 Enforces actiVities of killer T and B cells 0 Specifically targeted by HIV 0 Suppressor T cells 0 Suppresses actiVities of killer T and B cells 0 Helps protect against autoimmune response