There are protective factors of an organism which are directly directed on struggle with boleznetvornymi agents. It is immune system (specific factors of protection). Drugie factors - nonspecific. They not only protect us from infektsy, but also carry out a number of other functions. For example, in itself nepovrezhdennaja the skin and mucous membranes are enough strong protection from mnogih activators of infectious diseases. In norm existence obychnyh not pathogenic microorganisms on a skin, in intestines, in a mouth i on mucous membranes creates such conditions which interfere with development, a hence, and to harmful influence of pathogenic agents. At infringement etogo balance (dysbacteriosis) or considerable quantity influence infektsionnogo the agent there is "break" of the protective factor that leads infitsirovaniju (infection) and development of infectious process. It is necessary skazat and about such mechanisms of nonspecific protection of an organism adaptive haraktera, as maintenance of destruction of microorganisms at their hit in blood, sljunu, a plaintive liquid at the expense of presence in these environments of albumens, povrezhdajushchih pathogenic agents. Some physiological certificates zhiznedejatelnosti the person as otkashlivanie mokroty, chihanie, mocheispuskanie, otshelushivanie a blanket of a skin, etc., also play a protective role since pri it there is a mechanical removal of the microbes which have got to an organism. Spetsificheskaja immunity to infectious diseases is provided dejatelnostju the immune system presented constantly circulating in blood i to lymph by cages (limfotsitami) and special cellular communities - bodies, razbrosannymi on all body (lymph nodes, mindaliny, a spleen, limfoidnye educations in intestines, etc.) . The immune system is universalnym the mechanism of protection from alien (unusual for an organism cheloveka) albuminous, polisaharidnyh, fatty and kolloidnyh substances. From such veshchestv also pathogenic agents, in particular, consist. These substances it is accepted nazyvat antigenes. In reply to action of antigenes the immune system develops antitela - special albumens against antigenes. Antibodies are presented immunoglobulinami and developed limfotsitami. It is important, that specificity of antibodies ochen high, i.e. on a certain antigene are formed only peculiar to it antitela. In case of an antigene and antibody meeting there is an action blocking pervogo, that is carried out by the difficult mediated interaction of many veshchestv and cages of fabrics of a human body. Education specific antitel against a certain antigene (antigenes) finds applied primenenie in main principle of vaccination against infectious diseases - sozdanie protective level of antibodies against activators of infections. Presence antitel after the transferred infectious disease and their preservation defined vremja at sufficient level explains also immunity (immunity) from these infektsy for the period of existence of protective antibodies. After some infections (measles, krasnuha, a chicken pox, etc.) repeated disease practically nevozmozhno; at others (a flu, a pseudo-tuberculosis, leptospiroz, a dysentery, etc.) immunitet short or insufficient, that finds the reflexion in vozmozhnosti repeated diseases by these infections. The newborn child in protsesse pre-natal development and with chest milk after a birth receives from materi its antibodies to infections which it faced to pregnancy and in vremja vynashivanija a fruit. The quantity of these antibodies decreases in due course, however v the majority of their cases it is enough for protection on the first year of a life of the child. Vyjavlenie specific antibodies by means of antigenes (and return vzaimosvjazi) underlies, so-called, immunologicheskih reactions, pozvoljajushchih to diagnose infectious diseases that finds very wide primenenie in applied medicine. Speaking about immunity, it is impossible not skazat about one protective property already other blood cells - nejtrofilov (nejtrofilnyh granulotsitov). It fagotsitoz, i.e. Capture, dissolution and vyvedenie (digestion) of alien substances which activators infektsionnyh illnesses concern also. Fagotsitoz in some cases is necessary to begin with vyrabotki antibodies since there is an original preparation of an antigene ("crushing" tseloj a microbic cage on substances making it). Besides, nejtrofil, "digesting" the whole microbic cages, reduces their quantity, so and snizhaet their pathogenic influence on a human body. Analyzing quantity nejtrofilnyh leukocytes in peripheral blood, it is possible to judge degree porazhenija an organism sick of the bacterial agent. Activity immunnoj systems can be broken under the influence of many reasons. Influence vrednyh environment factors (toxic substances, an ionising radiation, povyshennaja allergizatsija technogenic substances), insufficiency of a food and vitaminov, physical and psychological loadings (stress), in some cases antibiotikoterapija - here some reasons which promote inadequate otvetu immune system on influence of the infectious agent. Defective immunnyj the answer can lead to infectious disease weighting, development oslozhneny, to illness transition in a chronic current. In an arsenal modern meditsiny there are enough medical products and the ways allowing provodit correction of infringements of activity of immune system, but sometimes vypolnenie this problem are extremely difficult business. These short and, po-vidimomu, difficult for perception examples of existence nonspecific and spetsificheskih factors of protection of the person from pathogenic agents serve the purpose sozdat at the reader a common view about difficult mutual relations of microbes and organizma the person in razvitiii to infectious disease.