innate (nonspecific) defenses

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innate (nonspecific)defenses host defenses are composed of two complementary, frequently interacting systems: innate (nonspecific) defenses, which protect against microorganisms in general, and (2) acquired (specific) immunity, which protects against a particular microorganism. present at birth immediate protection against variety of pathogens and foreign substances two types of immunity nonspecific (innate) physical and chemical agents lysozyme acute phase proteins complement system cytokines (chemokines) phagocytes (granulocytes, macrophages) natural killer (nk) cells dendritic cells toll-like receptors specific (adaptive) antibodies (b lymphocytes) t lymphocytes immunity signifies all those properties of the host that confer resistance to a specific infectious agent. immunity natural acquired or adaptive (specific) (innate, nonspecific) passive active acquired ( adaptive) immunity active passive natural artificial natural artificial (infection) (immunizing agents) clinical subclinical (placental transfer, colostrum) (administration of immune sera) first line of defense epidermis mucous membranes mucous cilia lacrimal apparatus of eyes saliva urine flow vaginal secretions defecation and vomiting sebum …

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icroorganisms less than 10㎛ diameter - the bronchial-associated lymphoid tissue (balt) gastrointestinal tract - in the stomach : lower ph, enzymes - in the intestine : enzymes - in the large intestine : the normal microbiota ⇒ preventing the establishment of pahtogens ⇒ destroy microorganisms genitourinary tract - urine kills some bacteria due to its low ph and the presence of urea and other metabolic end products the eye - tears contain large amount of lysozyme, lactoferrin and siga a second important defense is the mucous membrane of the respiratory tract, which is lined with cilia and covered with mucus. the coordinated beating of the cilia drives the mucus up to the nose and mouth, where the trapped bacteria can be expelled. in lacrimal fluid, sputum, saliva, blood, milk, tissues and organs lysozyme is found. it is found in some bacterial cells. nasal mucus is bactericidal for many microbes and …

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activation lectin pathway of complement activation late steps of complement activation inflammation stimulated by complement transferrins transferrins are iron-binding proteins. inhibit bacterial growth by reducing the amounts of available iron. transferrin transports iron from the small intestine, where the iron is absorbed, to the tissues, where the iron is used. transferrin and lactoferrin bind iron, limiting the growth of pathogens in the blood. lactoferrin is present in tears, semen, breast milk, bile, and nasopharyngeal, bronchial, cervical, and intestinal mucosal secretions. transferrin is present in serum and the intercellular spaces of many tissues and organs. innate immunity depends on receptor-recognition of common pathogen-associated molecules pathogen-associated molecular patterns (pamps) help the innate immune system recognize pathogens toll-like receptors (tlrs) are signaling receptors on: macrophages dendritic cells endothelial cells tlrs on mphs, dendritic cells, epithelial cells cytokines! pamps recognition toll-like receptors (tlrs) play a crucial role in the recognition of invading pathogens and …

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eins perforin perforates cell membranes granzymes destroy cell proteins phagocytes phagocytosis neutrophils macrophages develop from monocytes wandering fixed figure 21.8a phagocytosis * * * killing mechanisms of phagocytes sem of macrophage engulfing e. coli cells on the surface of a blood vessel phagocytosis phagocytes recognize the enemy either directly, by binding to components on the surface of the organism or indirectly, by binding to a foreign entity that has antibody bound to it. microbial evasion of phagocytosis inhibit adherence: m protein, capsules streptococcus pyogenes, s. pneumoniae kill phagocytes: leukocidins staphylococcus aureus lyse phagocytes: membrane attack complex listeria monocytogenes escape phagosome shigella prevent phagosome-lysosome fusion hiv survive in phagolysosome coxiella burnetti natural killer cells recognize and kill abnormal cells nk cells are formed in the bone marrow, and migrate to: tonsils lymph nodes spleen when activated, they produce cytokines that trigger response by macrophages and other cells then they move into …

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rs secreted by immune cells (mostly) that act on other cells to regulate their activity; many are called “interleukins” (il-1, il-2, etc.) cytokines have many functions, we’ll focus on a few central functions of a few key cytokines a subfamily of cytokines primarily functions in directing migration of cells, these are called “chemotactic cytokines” or “chemokines” * - monokines, lymphokines, interleukines colony stimulating factors, chemokines, interferon - the four cytokine families function : • autocrine • paracrine • endocrine a summary of innate and acquired immunity innate immunity rapid responses to a broad range of microbes acquired immunity slower responses to specific microbes external defenses internal defenses skin mucous membranes secretions phagocytic cells antimicrobial proteins inflammatory response natural killer cells humoral response (antibodies) cell-mediated response (cytotoxic lymphocytes) invading microbes (pathogens) break ! natural killer (nk) cell recognition

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innate (nonspecific)defenses host defenses are composed of two complementary, frequently interacting systems: innate (nonspecific) defenses, which protect against microorganisms in general, and (2) acquired (specific) immunity, which protects against a particular microorganism. present at birth immediate protection against variety of pathogens and foreign substances two types of immunity nonspecific (innate) physical and chemical agents lysozyme acute phase proteins complement system cytokines (chemokines) phagocytes (granulocytes, macrophages) natural killer (nk) cells dendritic cells toll-like receptors specific (adaptive) antibodies (b lymphocytes) t lymphocytes immunity signifies all those properties of the host that confer resistance to a specific infectious agent. immunity natural ac...

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