Irritability and stimuli
The ability of the body, its organs and tissues alter metabolism in response to stimulation is called irritability.
Irritability is determined plasticity of proteins. In its simplest form it manifests as irritability direct interaction between cells and food as the capture and assimilation of food. Certain external environment cause an increase or decrease metabolism, quantitative and qualitative changes. These metabolic changes are accompanied by a release of energy and can manifest itself in the movements of the entire body or bodies. These movements occur as a result of biochemical processes rhythmic release of energy, causing the movement, compression or tension of proteins, which leads to the displacement of the body in space by external influences.
Irritation – the effect of different forms of motion on the body or its organs, tissues and cells. Various forms of matter in motion, producing irritation, called irritants.
In the body, the following three groups of stimuli:
- 1. The physical – mechanical, thermal, electrical, light – electromagnetic waves of different lengths, visible and not visible to the eye, infrared and ultraviolet radiation, radioactive radiation (radioactive “labeled” atoms, alpha-, beta – and gamma-rays, X rays) . 2. Chemical – acids, alkalis, salts, toxins, and so on. D. 3. Biological – animals, plants, microbes and viruses on the surface acting as a highly organized animal organisms and able to get inside organisms.
There are also physical and chemical stimuli, physical and chemical actions which occur simultaneously, such as a radioactive ionizing radiation, salt.
Irritants are different from each other not only in quality but also in strength. One and the same stimulus, can be mild, moderate or high strength depending on the dose. Stimuli can act from outside on the outer surface of the body or inside the internal organs, tissues and cells.
External stimuli are various forms of motion of matter surrounding the body (electrical, mechanical, chemical, etc.). Internal stimuli are changes in the chemical composition of the internal environment (blood, lymph, cerebrospinal fluid and tissue), as well as mechanical influence and change the pressure acting on the various receptors of internal organs and tissues, causing changes in bodily functions and organs.
The stimuli may be natural, operating in a given tissue in normal natural conditions of existence of the body. These stimuli given tissue or organ adapted in the process of phylogenesis and ontogenesis. These stimuli are called adequate. For example, skeletal muscle adequate stimuli, causing her excitement to be a wave of excitation flowing to her on the motor nerves. In accordance with an adequate stimulus receptors are divided into perceiving light, sound, chemical, heat, cold and other stimuli.
Stimuli may be such changes in the external or internal environment, the perception of which are not adapted all the receptors or just this receptor. These stimuli are called inadequate, or inadekvatnymi. This group includes mechanical, electrical and other irritants that can, with sufficient intensity to cause excitement in every cell, tissue and organ in the direct action on them. Because of inadequate stimuli greatest importance for the study of physiological properties has an electric, current. Its advantages over the chemical or mechanical stimulus are that it, firstly, to quickly and easily dispensed by the strength, duration and nature, and secondly causes excitation without damage, even after the termination of stimulation leaves no irreversible changes in the tissues Third, the electric current generated in the excitation and therefore its effect is close to the natural mechanism of the emergence and spread of excitation.
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