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Immune System
Question | Answer |
---|---|
Innate (non-specific) defenses | non-specific, born w/ them: 1st line of defenses= surface barriers (skin, mucous membranes); 2nd line= internal defenses (phagocytes, fever, NK cells, antimicrobial proteins, inflammation) |
Adaptive (specific) defenses | more commonly associated, respond to SPECIFIC entities in body; 3rd line of defenses= Humoral immunity (B cells)- through fluids, Cellular immunity (T cells)- through cell-to-cell contact |
surface barriers: skin | keratinized stratified epithelium secretions (acid mantle, dermicidin)- enzymes that combat bacteria |
surface barriers: mucous membranes | acid (stomach), mucus, lysozyme (bacteria get stuck) |
surface barriers: beyond epithelium | Hyaluronic acid: viscous component of ECM (extracellular membrane) |
internal defenses: phagocytes | Macrophages, Neutrophils, Eosinophils engulf pathogens |
internal defenses: basophils, mast cells | Histamine: vasodilator (more blood to site of injury), Leukotrienes: attract leukocytes Heparin: anticoagulant |
internal defenses: fever | Mediated by pyrogens (signal that reset "thermostat"), Metabolic rate increases w/ higher temp, Spleen and Liver sequester iron & zinc needed for bacterial cell division |
internal defenses: NK cells | Non-selective lymphocytes that destroy cancerous or infected cells |
internal defenses: antimicrobial proteins- interferons | Interferons: newly infected cells send warning message to neighbors; interferes w/ virus infection but does not KILL virus; protects neighboring cells by degrading mRNA (blocks protein replication) |
internal defenses: antimicrobial proteins- complement | Complement: 1. job= Lyse bacteria 2. “label” bacteria for destruction 3. Enhance inflammatory response |
internal defenses: inflammation | Tissue injury --> release of chemical mediators of tissue repair and WBC recruitment |
hallmarks of inflammation | Heat, Redness, Swelling, Pain |
adaptive defenses: characteristics | Specificity, Systemic, Memory |
humoral immunity | B lymphocytes release antibodies to the blood --> bind to antigens (foreign substance generating immune response) |
cellular immunity | T lymphocytes bind antigens and themselves attack cells |
forms of immunity | natural active, natural passive, artificial active, artificial passive immunity |
natural active immunity | Production of one’s own antibodies or T cells as a result of infection or natural exposure to antigen |
natural passive immunity | Temporary immunity that results from antibodies produced by ANOTHER PERSON, ex: Fetus/newborn acquires antibodies from mother through placenta/milk |
artificial active immunity | Production of one’s own antibodies/ T cells as a result of VACCINATION against disease; Vaccine: consists of dead pathogens that stimulate the immune response (keep from developing disease bc body already seen antigen) |
artificial passive immunity | Temporary immunity that results from the INJECTION of serum (antibodies) from ANOTHER PERSON or ANIMAL; ex: Treatment for snakebite, botulism, rabies, tetanus, and other diseases |
adaptive immune system: cells | LYMPHOCYTES (B cells, T cells): Have to have ability to recognize antigens (competent), Self-tolerant to avoid attacking itself (own body), Each is UNIQUE (different antigen receptors) |
lymphocyte production | “Born” in the red bone marrow, Descendant of the pluripotent stem cells (PPSCs), During fetal development- B cells remain in BONE MARROW & T cells migrate to THYMUS; Lymphocytes colonize bone marrow --> travel in the blood and into the body’s tissues |
Antigen Presenting Cells | required by B & T cells to recognize ANTIGEN; =macrophages, B-cells, reticular cells (in lymphatic tissue), dendritic cells |
4 types of T-cells | Cytotoxic T cells (kill cell), Helper T cells (Help promote TC cell & B cell action), Regulatory T (limit immune response), Memory T cell (memory for immunity; descend from cytotoxic t) |
cytotoxic t-cell process | binds to antigen-presenting cell (APC) w/ exact RECEPTOR --> t-cell undergoes cell division --> pluck out receptor that matches antigen, duplicate over and over --> many t-cells all w/ receptors go out into body to FIND ANTIGEN --> destroy |
helper t-cells | also bind to antigen --> reproduce, make memory cells; work together w/ NK, B, T cells (work only when helper t cells also activated) |
humoral immunity | A more indirect method of defense than cellular immunity; B cells produce antibodies --> bind to antigens, tag for destruction by other means; recognition, attack, memory Variable regions of antibodies get variability from SOMATIC RECOMBINATION |
humoral immune response | antigen RECOGNITION, antigen PRESENTATION (helper t cell binds to b cell), DIFFERENTIATION (some cells of clone become memory cells, most become plasma cells), ATTACK (plasma cells secrete antibody) |
Primary & secondary response | primary response: takes a while (5 days) to respond to antigen (to run into antibody); antibodies build up to fight antigens, next time much QUICKER & ROBUST response |