Immunity is a complex of protective factors that ensure the body's ability to withstand the negative effects of external agents. The latter, for example, include bacteria, poisons, viruses, foreign bodies. In science, two types of immunity are distinguished : specific and non-specific. The latter will be discussed in the article.
general characteristics
Nonspecific immunity is directed against any antigen. The body with the penetration of a foreign substance forms an adequate response. The reaction can be on a humoral or cellular level. In the first case, the response is formed by the production of bactericidal compounds. Nonspecific cellular immunity provides the capture of foreign substances and a cytotoxic effect.
Items
Nonspecific protection factors (immunity ) are presented in the form of anatomical barriers, secretory molecules and other components. The first include epithelial mucous layers, skin, oscillations of the bronchopulmonary cilia and intestinal contraction. A non-specific type of immunity is considered congenital.
Mechanical structures
Physical factors of nonspecific cellular immunity form various barriers to foreign agents. Epithelial surfaces are one of the most effective barriers. These barriers are virtually impenetrable to most agents. The first barrier is the skin. Desquamation (peeling) of the epithelium helps to remove bacteria and other infectious bodies. Intestinal motility, cilia movement ensure the release of the respiratory system and gastrointestinal tract from microorganisms. Saliva and tears, washing the mouth and eyes, help prevent infections. Protection also provides and the mucosa of the respiratory tract and gastrointestinal tract.
Chemical compounds
Nonspecific immunity is provided in a variety of ways. Of no less importance are the chemical compounds formed by the penetration of agents. So, the development of bacteria slows down under the influence of sweat fatty acids. Phospholipase and lysozyme present in nasal secretions, tears and saliva have a destabilizing effect on the membrane of pathogenic microorganisms. Bacterial growth slows down with a low pH of gastric secretion and sweat. Low molecular weight proteins (defensins) present in the digestive tract and lungs have antimicrobial activity. The normal flora of the skin and in the gastrointestinal tract is able to prevent the colonization of pathogenic agents by producing toxic compounds or by competing with bacteria for attachment to the surface or nutrients.
Nonspecific immunity: humoral level
Of course, anatomical barriers very effectively prevent the colonization of surfaces by pathogenic agents. However, if they are damaged, the barriers are broken. This allows harmful compounds to enter the body. In such cases, non-specific immunity is activated at the humoral level. Its elements are present in serum or accumulate in the site of localization of infection.
Systems
When pathogenic agents enter the body, defense mechanisms are activated . The complement system is one of them . Its activation is accompanied by the mobilization of phagocytes, lysosomes, and an increase in vascular permeability. Another mechanism is the coagulation system. It is activated depending on the severity of tissue damage. Some products of the system provide a non-specific protective response by increasing vascular permeability. They act as chemoattractants - substances that, when attached to agents, provoke their movement. In addition, some products have an antimicrobial effect. These include, for example, beta-lysine. This protein is produced by platelets during coagulation. It lyses many gram-positive bacteria. Transferrin and lactoferrin bind the iron necessary for microbes, limiting their growth. Interferons have the ability to limit the replication of viruses. Lysozyme is destructive to the membrane of bacteria.
Nonspecific immunity cells
Part of the response to infection is the mobilization of polymorphonuclear eosinophils, neutrophils, macrophages. They move to the site of localization of bacteria. These cells are considered the main line of defense of non-specific immunity. Neutrophils - polymorphonuclear leukocytes are sent to the site of infection and capture bacteria. Immunity cells can destroy them intracellularly or move into extracellular traps. In addition, neutrophils are involved in tissue repair after elimination of the infection.
Macrophages
These elements also have the ability to phagocytose (capture) pathogenic elements and destroy them. Deactivation of agents is performed at the intracellular level. Macrophages have some features. For example, they have the ability to extracellular (extracellular) self-destruction. In addition, elements are involved in tissue remodeling.
Additionally
In addition to the above cells in the non-specific immune system, there are natural and lymphokine-activated killers. These elements are capable of killing tumor agents infected with an infection. Killers are not considered part of the inflammatory response. However, in non-specific immunity they play a significant role. Also in the system are eosinophils. The proteins of their granules are effective against a number of parasites.
Inflammation
The main objective of this reaction is the separation of pathogenic organisms and their toxins that have penetrated the tissues, and then their destruction. Of particular importance in the inflammatory process are histamine, serotonin and other biologically active components. They help increase the permeability of capillaries, ensuring the development of edema. Neutrophils, macrophages, antibodies, complement are in the fluid present at the site of the accumulation of agents. They provide neutralization of bacteria and their toxins. In the focus of inflammation, phagocytes are concentrated. They form a kind of fence that prevents the spread of infection. Here fibrinogen begins to accumulate. Turning into fibrin, it provides thrombosis of small lymphatic and blood vessels. As a result, an obstacle is created for the spread of infection through them. In the inflammatory focus, blood supply is disturbed. Due to this, acid products of metabolic processes begin to accumulate and the pH decreases. This adversely affects the growth and reproduction of microorganisms.