Immunology Revision PDF

Immunology  Key terminology Microbe - Organisms of microscopic size, some pathogenic and others beneficial in health. Antigen - Substance/maker on infection-causing organisms that triggers immune response in the body. Cytokine - Small proteins important for controlling immu...

Immunology  Key terminology Microbe - Organisms of microscopic size, some pathogenic and others beneficial in health. Antigen - Substance/maker on infection-causing organisms that triggers immune response in the body. Cytokine - Small proteins important for controlling immune cell growth and activity. Antibody - Special proteins produced by activated B cells to attack/weaken antigens. Phagocyte - Immune/white blood cells that engulf and digest pathogens. (Macrophages & neutrophils). Antigen presenting cells (APCs) - Cells that process and present antigens in a recognisable form to T cells. (Crucial for initiating adaptive immunity) Proteins (within immune system) - Large molecules of one or more chains of amino acids in specific order. Opsonins - Molecules that coat pathogens, making them more recognisable to phagocytes. (IgG, C3b) Phagocytosis - The process by which phagocytes engulf and digest pathogens. Apoptosis - Programmed cell death that eliminates unwanted cells during development and maintains tissue homeostasis. Complement system - Part of innate immune system, important role in host defence and inflammation, helps to eliminate and remove pathogens and damaged cells.  Key organs & tissues of the immune system O Primary organs; make specialised immune system cells; lymphocytes. & Secondary organs; within these organs, immune system cells ‘fight off’ foreign substances. Mucous membranes in nose > - and throat Tonsils - - Lymph nodes - Thymus - Bone marrow Skin - - Spleen Bowel - - Mucous membranes in bladder and genitals PRIMARY Bone marrow - produce immune system cells, including B lymphocytes that mature here. Thymus - site of T lymphocyte maturation, coordinates immune responses. SECONDARY Spleen - filters blood, stores immune cells, breaks down old red blood cells. Tonsils - prevents foreign substances from entering through nasal and oral cavity. Lymph nodes - filters lymph fluid and traps pathogens to trigger antibody production. Mucous membranes - immune system cells lie under mucous membrane, acts as protection barrier. Innate VS. Adaptive Immunity Innate immunity - - Adaptive immunity - First line of defence, immediate or hours. Develops over time. Non-specific, non-antigen dependent. Specific, antigen dependent. No immunological memory. Immunological memory. Includes barriers such as skin & mucous membranes, Involves B and T lymphocytes and and immune cells like phagocytes. production of antibodies. Barriers ass. with oral cavity Oral mucosa Oral epithelial cells Saliva Tonsils Antigen-presenting cells Secretory IgA Key barriers of innate immune system TYPE MECHANISM EXAMPLE Skin, mucous membranes; Anatomic Initial physical barrier - stops pathogens. respiratory tract and oral & nasal cavities. Low pH/acid in stomach, body Regulates immune response through body Physiological temperature and chemical systems. mediators; saliva, tears. Phagocytic/ Engulf and digest pathogens - break Macrophages & neutrophils - Endocytic down of foreign substances. pathogen targeted sites within body. PRRs detect & trigger immune response Cytokines release and histamine. Inflammatory to injury - protect from pathogens and Site of trauma; internal or external. tissue damage.  Cells of the immune system - ALL white blood cells! Innate system cells Neutrophils - Granulocyte, Macrophage - Mononuclear, phagocyte. phagocyte. Phagocytosis, degranulation Phagocytosis, antigen presentation to T (discharge of cell contents) - cells, release cytokines, long-lived. short lived. Destroy old, dead and damaged cells Bacteria and fungi. within body. Basophils - Granulocyte Eosinophils - Granulocyte Degranulation, release of Degranulation, release of enzymes, histamine, enzymes and growth factors and cytokines. cytokines. Parasites, various allergic Various allergic reactions. reactions. Mast cells - Granulocyte Dendritic cells - Mononuclear leukocytes When activated, release Link innate & adaptive immunity (messenger). inflammatory mediatorscytokines. Antigen presenting cells, key regulator, turn Host defence to parasitic on cell surface receptors to active T cells. infections and allergic reactions. Capture and process antigens. Adaptive system cells Lymphocytes (T cells) - Mononuclear leukocytes Mature in thymas. T Helper cells (Th) - immune response mediators. Cytotoxic T cells - destroy infected & diseased cells on activation. Natural killer cells - destroy infected and diseased cells. Mainly involved with cel mediated immunity. T cells essential for helping B cells respond to antigens. Lymphocytes (B cells) - Mononuclear leukocytes Plasma cells - production of antibodies. Memory cells - effector, secondary immune response. Targets foreign antigens. Mature in bone marrow. Antibodies - Immunoglobulin (Ig) Special proteins produced by activated B cells. Specifically recognise and bind to antigens to attack/weaken and mark them for destruction. Body can create new antibodies in response to pathogens or vaccines. Each antibody has a different role in fighting infection; 5 main types; Immunoglobulin A (IgA) 2 forms; secretory & serum IgA. Secretory - found in linings of respiratory & digestive system, saliva, tears and breast milk. Antiseptic part of mucous membranes. Activate complement system in prescience of lysosomes to kill certain organisms. Serum - cannot activate complement system. Immunoglobulin D (IgD) Low levels in blood, cannot activate complement system. Found on surface of B cells. Half of antigen specific receptors on B lymphocyte membranes are composed of IgD. Supports B cell maturation and activation. Immunoglobulin E (IgE) Found mainly in skin, lungs, mucous membranes; small amounts. Most attach to mast cells and basophils to cause release of anti-histamine in bloodstream. High levels found in those with allergies; hay-fever, asthma. IgE antibodies can cause allergic reactions. Immunoglobulin G (IgG) Most common antibody in blood tissue & fluid; 75%. Protect body from viral and bacterial infections; diffuse toxins and spread microbes. Mainly occurs in acquired/secondary immune response. Immunoglobulin M (IgM) Found in blood and lymph system; large role in immune regulation. Largest immune molecule and short lived. Usually first antibody to response in defence against infections; innate/primary immune response.