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MLT-Host Defense


The process of an infection? Contact: Finding a portal of entry. Colonization: Attaching onto human firmly. Infection: Surviving inside human body, entering the tissues and multiplying. Infectious diseases Causing damage in human body.
Levels of Immunity 1st: Any physical and chemical barriers, non specific, like eye lid and tears. 2nd: Inflammation and phagocytosis, non specific. 3rd: Immune response, specific.
Why skin can act as a barrier? 1.Dead epithelial cells and insolubale keratin, which is impermitable to water and microbes. 2.Constantly shed off, bring away the microbes away. 3.Sebaceous fluid has fatty acid, batericidal. 4.High lactic and electrolyte conc, inhibit growth.
Major components for 2nd line defence? Phagocytosis, cytokines, complement proteins.
Purpose of Phagocytosis? To ingest and eliminate foreign microbes and materials. To represent antigens for immune respond.
The types of Phagocyte? Neutrophils, monocytes, macrophages.
Why Phaogocyte can recognise foreign microbes? By Pathogen-associated molecular patterns (PAMPs) presented on the microbial cell surface.
How the microbes are killed by Phagocytes? 1.By strong oxidative agents, e.g. halogen ions (OCI-), superoxide anion (O2-), generated by Myeloperoxidase. 2.By other mechanisms, such as digestion by a proteolytic enzyme, liberation of lactic acid and nitric oxide (NO).
Functions of complement proteins? 1.direct lysis of pathogens. 2.enhance phagocytosis. 3.enhance inflammation.
How does Natural Killer(NK) cell work? 1.Not phagocytic. 2.has receptors to differentiate uninfected cells from infected cell. 3.Secret perforin and granzymes to damage the cells.
What are the receptor on NK cells? Killer activating receptor Killer inhibitory receptor
Major component of 3rd line defence? Lymphocytes development -> antigen presentation -> B cells or T cells activation -> Antibodies(B cells) and Cell-mediated respond(T cell)
The 3 population of B cell? 1. Memory cell, allows rapid immune respond in 2nd infection. 2. Regulatory cell, suppress T helper cells to dampen autoimmune response. 3. Plasma cell, produce antibody
Types of Antiboy? IgG: Major systemic Ab, long term immunity, neutralize toxins, opsonizes, fixes complement. IgM:Produced at first response to antigen. IgA:Secretory Ab, on mucous membranes. IgE:Antibody of allergy; worm infection. IgD:Act as receptor on B-cells.
Functions of antibody? 1.Opsonization: bacteria coated by Ab can be engulfed more readily by phagocytes. 2.Neutralization: Ab fills the receptors of pathogen, to prevent it attach to host. 3.Agglutination: causing immobile . 4.Complement fixation: causing cell lysis.
What are the types of 3rd line defence? 1. Humoral Immunity 2.Cell-mediated immunity
What are the major components of T cell respond? 1. T helper cell: activate cytotoxic T cell and B cell, promote inflammation 2. Cytotoxic T cell: secrets perforin that punches hole in target cell membrane. 3. Memory T cell
Created by: kencho