Immune System

Immune System: pg. 842-865 Non Specific (innate) defense - born with immediate defense - no specific response to specific invaders - includes: skin, mucous membranes(1st line defense), anti microbial proteins, N.K cells, Phagocytes, Inflammation & Fever (2nd line of defense) First Line Defense  Skin: o physical barrier, tough to cross o it sheds, secrete sebum,  Mucous Membrane: o lines the body cavities that open to the outside world o trap invaders o hairs  Other fluids o tears, saliva, urine, vaginal secretions, defecation, vomiting Second Line  Antimicrobial Substances o 1. Interferons – when lymphocytes, macrophages, fibroblasts get infected, produce interferons. Interferons go to neighboring cells & make ant-viral proteins cant stop virus from entering but you can stop reproduction o 2. Compliments system: (a major way to fight infections) – usually inactive, Proteins in plasma, causes cytolysis (cells bursts) opsonization (binding to the surface to make it easy to recognize) this promotes phagocytosis o 3. Transferrins – bind to iron in the cell so bacteria cant use it o 4. Antimicrobial Proteins – Body’s own antibiotics   Natural Killers & Phagocytes: N.K cells: o attack any body cell displaying abnormal or unusual membrane proteins o bind to the cell, release toxic substances, poke a hole in the cell (perforin does this)

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o release protein digesting enzymes Phagocytes consume microbe Inflammation – non-specific o Chemotaxis, increased permeability o heart redness Fever: Abnormally high body temp o Hypothalamus resets body “thermostat” by chemicals

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Specific Defense: aka (Adaptive immunity) 3rd line of defense    bodies ability to defend against specific virus bacteria, toxin etc… Antigen is recognized as foreign & Provokes an immune response T cells and B cells are both made in the red bone marrow o B cells exit mature o T cells must migrate to Thymus (which changes shape when you age) so grows until puberty by then it levels out then it decreases as you age after that Lymphocytes have antigen receptors (proteins in plasma membrane) o T cells - (D4 – helper and D8 – cytotoxic) – Memory cells  suppressor T cells  Cell mediated immunity (cell to cell) – Cytotoxic T cells release enzymes which kill the cell, can also release perforin. T Cell Activation – double recognition process o Antigen recognition & co-stimulation Antibody Mediated Immunity (Humoral Immunity) o B cell o antigens in the body fluid o B cells transform in plasma cell or memory cells o plasma cells secrete immunoglobulin o immunoglobulin’s are made up of heavy & light chains of polypeptides ******** o Ig G – main one, enhances phagocytosis, passed mother to fetus o Ig A – SALIVA, mucous, protect mucous membrane

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o Ig M - occurs as a pentamere (5 sided figure) its activates compliment. Also a B cell receptor o Ig D – B cell receptor o Ig E – Allergies & Hypersensitivity  Self Recognition & self Tolerance – normal & necessary

Definitions  Immunogenicity – provoke an immune response  Reactivity – Ability of the antigen to react with the antibodies or T-cells that it produced  ***Hapten – has reactivity but lacks Immunogenicity*** Grafts     autograft – one body site to another on the same person. isograft – between identical twins allograft – between the same species xenograft – between different species