Irritant

Irritant is medicinal substances, causing the local application irritation of sensitive nerve endings. Irritant belong to different classes of chemical compounds. They, as a rule, well-soluble in lipids, which allows them to penetrate through the epidermis and surface layers of epithelium and achieve sensitive nerve endings.
When applying annoying funds on the skin and mucous membranes occurs local reaction in the form of redness and swelling, as well as the characteristic irritation of this receptor fields reflexes. The therapeutic effect of irritating means explain the emergence of reflexes, which lead to changes in the activities of some of the nerve centers (respiratory, vasomotor) or condition of internal organs (change blood, metabolism). Action annoying tools can speed up the resolution of the inflammatory process and reduce associated with this process pain (distracting). Thus, for example, due to the action of yellow cards (see) when pneumonia and turpentine (see) when myositis. Irritant, affecting the mucous membranes of the upper respiratory tract, stimulates the respiratory and vasomotor centers (see Ammonia). The irritation of the mucous membranes of the oral cavity occurs expanding coronary vessels in angina (see Validol, Menthol). Under the action of bitterness (see), receptors mouth reflex increased anxiety "food center". Irritation of mucous membrane of the stomach leads to stimulation of the vomiting center, depending on the intensity of exposure cause expectorant or emetic effect (see Expectorants).

Irritant (Dermerethistica) - medicinal substance causing the local action irritation of sensitive nerve endings and characteristic irritation of this receptor fields reflexes. Under the influence of annoying funds on the skin develops local reactions consisting of three components ("triple reaction"): the bright redness and swelling at the place of the direct impact of irritating funds and the surrounding this place the bezel more moderate hyperemia. The first two components of the reaction depend on the expansion of capillaries and improve their permeability, which is explained by the effect on the capillaries of histamine, which is released from the cells under the action of a irritating agents. The third component is due to axon-reflex. This reflex is carried out within sensitive axon in the distribution of pulses resulting from irritation of the receptors, vasodilator branches, extending from sensitive nerve fibers to the arterioles of the skin.
Previously used irritant, causing more intense local reaction with the formation of bubbles, suppuration and even necrosis (for example, Spanish fly). Such R. S. now practically obsolete. However, such reactions may occur, and under the influence of the currently used R. S. moderate strength; it happens at the excessive length of their impact on the skin.
Irritant used in inflammatory diseases of internal organs, as well as in myositis, neuritis, arthralgia and so on (see Mustard, Ammonia, Turpentine). Under the influence of P. S. accelerates the resolution of the inflammatory process
and weaken associated with this process pain. Therapeutic action R. C. explain segmental trophic reflexes from skin to underlying tissues and internal organs. By L. A. Orbeli, it axon-reflexes propagating within the ramifications of the sympathetic nerve fibers. It is possible, however, that these reflexes are closed in the spinal cord, and the afferent their part are sensitive nerve fibers, and efferent - sympathetic fibers originating in the side horns spinal cord. As trophic kutano-visceral reflexes are segmental character, irritating means should influence zone Ged corresponding localization of the inflammatory process. When exposed R. S. vast surface of the skin pulses that occur in sensitive nerve endings, apply to newsegmentonly departments of Central nervous system, in particular on the respiratory and vasomotor centers of the medulla oblongata. This is based on the use of mustard poultices in vascular and respiratory failure. Reflexes on the respiratory and vasomotor centers arise during stimulation of the sensitive receptors in the lining of the nose. As a means for stimulation of these receptors use ammonia.
Some irritant have a selective effect on the receptors, perceiving feeling cold (see Validol, Menthol). Under the influence of such R. S. arise reflexes of the same nature as and when exposed to cold. Therefore, the application to the skin or on the mucous membranes such R. S. cause vasoconstriction. The therapeutic effect of such annoying funds with strokes, has probably the result of the expansion of the coronary vessels as a result of stimulation of cold receptors in the lining of the mouth.
Irritant meet in different classes of chemical compounds. As a rule, R. S. differ General physico-chemical feature - solubility in lipids, allowing them to penetrate through the epidermis and surface layers of epithelium and achieve sensitive nerve endings. Good solubility in lipids differ, in particular, is widely used as R. C. essential oils.
Wide practical application have R. E. providing selective effect on certain receptors in the intestinal tract. The resulting reflexes depend on the localization of the receptors, which operates this R. S. At the irritation of the receptors of the mouth, perceiving the sensation of the bitter taste that comes reflex increase in the excitability of "food center" (see Bitterness). The irritation of the receptors in the lining of the stomach leads to reflex excitation of vomitoxin centre, depending on the intensity of irritation causes expectorant or emetic effects (see Expectorants). The irritation of the receptors in the lining of the intestine leads to reflex strengthening its peristalsis (see Laxatives means).