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Innate immune system cells prevent free growth of microorganisms within the body, but many pathogens have evolved mechanisms to evade it. [21] [22] One strategy is intracellular replication, as practised by Mycobacterium tuberculosis, or wearing a protective capsule, which prevents lysis by complement and by phagocytes, as in Salmonella. [23]
In the first definitive book on defence mechanisms, The Ego and the Mechanisms of Defence (1936), [7] Anna Freud enumerated the ten defence mechanisms that appear in the works of her father, Sigmund Freud: repression, regression, reaction formation, isolation, undoing, projection, introjection, turning against one's own person, reversal into the opposite, and sublimation or displacement.
Many species, however, use mechanisms that appear to be precursors of these aspects of vertebrate immunity. Immune systems appear even in the structurally simplest forms of life, with bacteria using a unique defense mechanism, called the restriction modification system to protect themselves from viral pathogens, called bacteriophages. [158]
The mucosal immune system consists of a cellular component, humoral immunity, and defense mechanisms that prevent the invasion of microorganisms and harmful foreign substances into the body. These defense mechanisms can be divided into physical barriers (epithelial lining, mucus, cilia function, intestinal peristalsis, etc.) and chemical ...
Each immunoglobulin class differs in its biological properties and has evolved to deal with different antigens. [5] Antibodies are synthesized and secreted by plasma cells that are derived from the B cells of the immune system. An antibody is used by the acquired immune system to identify and neutralize foreign objects like bacteria and viruses.
The recognition of intrinsic immunity as a potent anti-viral defense mechanism is a recent discovery and is not yet discussed in most immunology courses or texts. Though the extent of protection intrinsic immunity affords is still unknown, it is possible that intrinsic immunity may eventually be considered a third branch of the traditionally ...
There are two categories to which parts of the immune system are assigned: the non-specific, or innate immune system and the adaptive immune system.The non-specific response is a generalized response to pathogen infections involving the use of several white blood cells and plasma proteins.
In the first line of defense, inhaled bacteria are trapped by mucus and are swept toward the pharynx and are swallowed. [1] Bacteria which penetrate the mucous layer are dealt with a second line of defense which includes antimicrobial peptides that are secreted by the surface epithelium of the respiratory tract which kill many strains of ...