Immunity - immunity of the organism to alien agent, in particular infectious.
The presence of immunity is associated with hereditary and individually acquired factors, which prevent the penetration into the body and the reproduction of its various pathogenic agents (bacteria, viruses), as well as the action allocated to their products. The immunity can be not only against pathogenic agents: any alien for this organism antigen (such as protein) causes immunological reactions that result in the agent in any way removed from the body.
Immunity is diverse in origin, development, mechanism, and other features. Origin distinguish congenital (species, natural and acquired immunity.
Innate immunity is the specific feature of the animal and has a very high tension. Man has specific immunity to a number of infectious animal diseases (plague of cattle and other), the animals are immune to gonorrhea, typhoid, typhus, leprosy , and others In a number of cases, the tension natural immunity relative (in the artificial lowering of body temperature birds can infect them anthrax, to which they have specific immunity).
Acquired immunity is not an innate characteristic and originates in the life. Acquired immunity can be natural or artificial. The first appears after the disease and, as a rule, is strong enough. Artificially acquired immunity is subdivided into active and passive. Active immunity occurs in humans or animals after administration of vaccines (preventive or therapeutic purposes). The body itself produces protective patiotel. Such immunity occurs over a relatively long period of time (weeks), but persists for a long time, sometimes for years, even decades. Passive immunity is created after the introduction into the body ready protective factors - antibodies (immune sera, gamma globulin). Occurs it quickly (within a few hours), but is retained for a short period of time (usually a few weeks).
To acquired immunity applies the so-called infectious or non-sterile, immunity. He is not due to the transfer of the infection and the presence of her body and exists only as long as the body is infected (e.g. immunity to tuberculosis).
The manifestation of the immunity can be antimicrobial when the action protective factors, the body is directed against the agent, diseases (typhoid fever, plague, tularemia, and antitoxic (protection of the organism against toxins when tetanus, diphtheria, anaerobic infections). In addition, there are antiviral immunity.
A great role in maintaining immunity play the following factors: skin and mucous barriers, inflammation, phagocytosis, the barrier function of the lymphatic tissue, humoral factors, immunological reactivity of the organism cells.
The value of the skin and mucous membranes in the immunity of the organism to infectious agents due to the fact that in the intact condition they are impervious to most types of microbes. These fabrics are also sterilizing bactericidal, due to the ability to produce substances that cause the death of some microorganisms. The majority of the nature of these substances, the conditions and the mechanism of their action was studied not enough.
Protective properties of the organism are largely determined by inflammation (see) and phagocytosis (see). Protective factors include the barrier function of the reticuloendothelial system, (see) which prevents the penetration of bacteria in the body, which to some extent associated with the inflammatory process. A significant role in the immune system belongs specific protective factors serum blood (humoral factors)- antibodies (see)that appear in the serum after the disease, as well as in artificial immunization (see). They have specificity in relation antigen (see), which caused them to appear. Unlike the immune antibodies, the so-called normal antibodies are often found in the serum of people and animals, which are not transferred infection and were not subject to immunization. Non-specific factors of blood is the complement (Aleksin) - thermolabile substance (destroyed at a temperature of 56 degrees for 30 minutes)having the property to increase the effects of antibodies against a number of microorganisms. Immunological reactivity of the organism depends on age. The newborn she sharply reduced; in the elderly is less pronounced than in middle age.