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OCCUPATIONAL SAFETY AND HEALTH
General information about the human body and its interaction with the environment. Occupational Safety and Health
Occupational Safety and Health / Legislative basis for labor protection Without knowing "oneself", it is impossible to understand how one should protect "oneself" from the threats of the outside world, and therefore we will allow ourselves to recall some basic data of human anatomy and physiology. Modern man has gone through a long evolutionary path of adaptation to the environment, and the human body is a single whole, all systems and organs of which develop and function in mutual dependence and conditionality. Although the organism functions as a whole, dividing it into various systems is necessary to understand the functioning of the organism in the external environment, especially if these systems are either anatomically distinct enough, such as the circulatory and digestive systems, or are physiologically functional, such as , systems of thermoregulation and immunity. The human body is so complex that it is studied by a number of scientific disciplines. We will consider it in a very simplified way and only from the standpoint of ensuring human safety in the labor process. From these positions in the human body, with a certain degree of conventionality, we can conditionally name: (1) shaping systems, (2) life support systems and (3) control systems. The shaping systems include the bone and muscle systems, as well as the skin and a number of mucous membranes. Life support systems include all systems of exchange with the external environment (respiratory, digestive and excretory systems) and distribution of substances in the body between various organs (cardiovascular system). The control systems include the autonomic and central nervous systems. All body systems consist of various organs that are functionally interconnected with each other. Organs are built from various tissues. Tissues consist of cells and intercellular substance in which various biochemical processes take place. Every organ has blood vessels, and most have lymphatics. Nerves approach and branch out to all organs. The musculoskeletal system forms the human musculoskeletal system and ensures the body's autonomy, the ability to perform various actions and move in space. In addition, bones, muscles and skin provide protection for other, so-called internal organs, from direct exposure to the external environment. In addition to protective functions, the skin is involved in metabolism and thermoregulation. The heart and blood vessels form a closed system through which blood moves due to contractions of the heart muscle and vessel walls. Blood vessels are divided into three main types: arteries, capillaries, and veins. Arteries carry blood away from the heart. They branch into vessels of ever smaller diameter, through which blood enters all parts of the body. In the parts of the body farthest from the heart, the blood vessels are so small that they can only be seen under a microscope. It is these microscopic vessels, capillaries, that supply cells with oxygen and nutrients. After their delivery, blood loaded with metabolic end products is sent to the heart through a network of vessels called veins, and from the heart to the lungs, where gas exchange occurs, as a result of which the blood is saturated with oxygen. The respiratory, digestive and excretory systems serve to consume substances necessary for life from the environment and remove metabolic products (biochemical processes of life). Sweating through the skin plays an important role in maintaining the water-salt and acid-base balance of the body. On average, a person excretes 600 ml of water per day with sweat. With sweat, a huge (about 270) amount of chemicals is excreted. Anatomically, the nervous system consists of the central and peripheral systems. The central nervous system includes the brain and spinal cord, and the peripheral nervous system includes cranial and spinal nerves, as well as nerve nodes and plexuses that lie outside the spinal cord and brain. Incoming sensory information is processed by passing through specific pathways: for example, pain, visual or auditory nerve fibers. Sensitive pathways go in an upward direction to the centers of the brain. The result of the activity of the central nervous system is activity, which is based on the contraction or relaxation of muscles or the secretion or cessation of secretion of glands. The autonomic, or autonomic, nervous system regulates the activity of the involuntary muscles, the heart muscle, and various glands. Its structures are located both in the central nervous system and in the peripheral. The activity of the autonomic nervous system is aimed at maintaining a relatively stable state of the internal environment of the body: a constant body temperature or blood pressure that meets the needs of the body. The autonomic nervous system is divided into sympathetic and parasympathetic. The sympathetic system stimulates those processes that are aimed at mobilizing the body's forces in extreme situations or under stress. The parasympathetic system contributes to the accumulation or restoration of the body's energy resources. The sympathetic and parasympathetic systems act in a coordinated manner and cannot be seen as antagonistic. Together they support the functioning of internal organs and tissues at a level corresponding to the intensity of stress and the emotional state of a person. Both systems function continuously, but their activity levels fluctuate depending on the situation. The endocrine system consists of endocrine glands that do not have excretory ducts. They produce chemicals called hormones that enter directly into the blood and have a regulatory effect on organs distant from their respective glands. The central nervous system regulates the activity of all organs, systems and the whole organism as a whole and is a collection of nerve cells and processes extending from them. In this set of cell bodies located in the cranium (brain) and spinal canal (spinal cord), information is processed that comes to them through sensory nerves and comes from them to the executive organs through motor (to muscles) and autonomic (to internal organs) nerves. All nerves and their branches form the peripheral nervous system. The central nervous system organizes the processes of vital activity in accordance with the conditions of the external environment, changing the functioning of the work of individual organs and systems. At the same time, the functioning of all systems is closely intertwined. For example, in the process of transporting substances through the blood circulation, in addition to the cardiovascular system, the urinary system also participates, since the blood flow passes through the kidneys, and the respiratory system, since the blood flow passes through the lungs, and the digestive and hematopoietic systems. The basis of the influence of the digestive system on the cardiovascular system is their close relationship through water-electrolyte metabolism. The musculoskeletal system has a very great influence on the mechanical movement of blood. To put all systems into operation, the central nervous system (and the person along with it) must have information about the state of the external environment, which is achieved with the help of various analyzers and receptors of the so-called sense organs. Any analyzer consists of a receptor, nerve pathways and a brain end. Some of the receptors are adapted to perceive changes in the environment (exteroreceptors), and some - in the internal (interoreceptors). The receptor converts the energy of the stimulus into a nervous process. Pathways transmit nerve impulses to the cerebral cortex. There is a two-way connection between the receptors and the brain end, which ensures the self-regulation of the analyzer. The visual analyzer plays an exceptional role in a person's life and his relationship with the outside world. With its help, we get the lion's share (about 90%) of information. Through vision, we almost instantly and at considerable distances know the shape, size, color of an object, the direction and distance at which it is located from us. The visual analyzer includes the eye, the optic nerve and the visual center, located in the occipital lobe of the cerebral cortex. Second in importance after the visual analyzer is auditory. Only it allows us to receive information out of sight, for example, from behind, or in the dark from various distances almost instantly. Differences between the speeds of light and sound are perceptible to us when observing distant thunderstorms, explosions, etc. Another analyzer - the sense of smell also allows you to receive information from great distances, but representatives of the animal world are much better at it than humans. Olfactory receptors are located in the nose and perceive the smallest amount of a substance in the air, which is felt as a smell. Another analyzer - taste allows you to get information about the quality of food. We sense taste with receptors located on the tongue and oral mucosa. If a person were a contemplative of nature, then seeing, hearing, smelling and tasting would probably be enough for him. But a person wants to eat and multiply, and for this you need to act (you need to pick up a stick, you need to put your foot on a stone, you need to snuggle up to your own kind). And all this would be impossible if it were not for the sense of touch. Under the sense of touch we understand the sensations arising from the direct impact of the stimulus on the surface of the skin. The skin is literally stuffed with receptors of various analyzers. The tactile analyzer perceives touch and pressure on skin receptors. The temperature sensitivity of the skin is provided by two types of receptors - cold and heat. The spatial distribution of pain receptors is interesting. There are many of them where there are few tactile receptors, and vice versa. Pain receptors cause a withdrawal reflex from the stimulus, because a painful stimulus is a danger. Under the influence of pain, the body quickly mobilizes to fight the danger, the work of all body systems is rebuilt. The analyzers considered above are so important and have long been known to man that he called them sense organs: sight, hearing, smell, touch and taste. But besides them, a person has other analyzers and receptors. The human brain receives information not only from the environment, but also from the body. Sensitive nervous apparatuses are present in all internal organs. In the internal organs, under the influence of external conditions, certain sensations arise that generate signals. These signals are a necessary condition for the regulation of the activity of internal organs. Important analyzers are proprioceptors, which allow you to feel muscle tension and the spatial arrangement of the body and limbs. Despite the difference in the diverse receptors and analyzers, their functioning has much in common, since they all developed in the process of evolution to protect against dangers. In the real conditions of terrestrial habitation, a person is affected by a lot of very different, often weak, irritants. In the course of evolution, a person has developed the ability to perceive only those stimuli, the intensity of which reaches a certain certain value. Such a minimum adequately perceived value is usually called the lower absolute threshold of sensitivity or the threshold of perception. At the same time, perception always lags behind the onset of the stimulus for some time, called the latent (latent) period. Above the threshold of perception, the intensity of sensations slowly increases with increasing intensity of the stimulus, and their relationship can be approximately expressed by the Weber-Fechner logarithmic law. Such a connection between the stimulus and sensation is not accidental, since it allows us to reduce a very wide range of stimuli to a much narrower range of sensations, and the greatest values of the stimulus undergo the greatest transformation. High values of the stimulus are rare in nature and, as a rule, are associated with danger, about the occurrence of which the organism must be "warned". Therefore, with an increase in the intensity of the stimulus, there always comes a moment when the sensation is replaced by a special signal of danger - pain, from which the body wants only one thing - to get rid of, and, getting rid of it, saves itself from danger. Such a maximum adequately perceived value of the stimulus is usually called the upper absolute threshold of sensitivity or pain threshold. The interval from the minimum to the maximum adequately felt value (from the perception threshold to the pain threshold) determines the sensitivity range of the analyzer. Within its sensitivity range, the analyzer may no longer distinguish between two different, but close in intensity, stimuli. To assess this ability of the analyzer, they speak of a differential threshold (or threshold of discrimination), which is understood as the minimum difference between the intensities of two stimuli, which causes a barely noticeable difference in sensations. Like everything in the living world, threshold values are not strictly stable. They depend on many factors, often difficult to take into account. Therefore, all thresholds should be considered as statistical averages. In real conditions of activity, several stimuli simultaneously act on each analyzer of a person. Therefore, it is necessary to take into account not only the capabilities of the analyzer, but also the conditions in which a person will work. Therefore, when determining the optimal conditions for functioning, it is necessary to take into account the entire system of stimuli acting on all human analyzers. We emphasize that the division of the entire set of analyzers into separate systems is rather conditional. These systems clearly differ only in their receptors. In the vast majority of cases, a change in the nature of the organism's vital activity in response to a change in environmental conditions occurs with the participation of several analyzers, and then it is practically impossible to draw a clear line between them. For example, the vestibular apparatus, gravireceptors and proprioreceptors of muscles, tactile receptors of the skin, receptors of the organ of vision take part in the regulation of posture. In addition, in this case, all analyzer systems have the same actuator - the musculoskeletal system. It is even more difficult to single out individual analyzers in the case when the choice of reaction to an external disturbance is carried out consciously. In the course of evolution, a number of specialized systems have developed in the human body, fixed in the anatomical structure and physiological functioning of a person, designed to compensate for adverse changes in external conditions. Any change in environmental conditions automatically generates a corresponding change in the life processes in the body, aimed at ensuring that this external change does not lead to damage and death of the body. The changes in the internal environment of the body occurring under the influence of changes in the external environment are simultaneously aimed, on the one hand, at adaptation (adaptation) to new environmental conditions, and, on the other hand, at maintaining a relatively unchanged state (homeostasis or homeostasis) of the internal environment of the body and its functioning. Adaptation and homeostasis are interrelated and complementary processes, which are one of the most important features of all living systems. Without exaggeration, we can say that these are the main mechanisms for the safe functioning of the human body, which determine its health and even life. Under normal conditions of a normally changing external environment, an organism that successfully copes with the need to adapt and maintain homeostasis is healthy. When the body, in order to maintain homeostasis, switches on the mechanisms of compensatory reactions, we have to talk about the so-called premorbid state - the state of pre-illness. In this state, there are still no clinical symptoms of the disease, as modern medicine understands it, but, unfortunately, it is impossible to say that a person is healthy. When an organism cannot adapt to environmental conditions, it becomes ill and/or dies. It follows from the foregoing that ensuring human safety consists in such regulation of the external environment (working conditions) and the functioning of the internal environment of the worker's body, which, under the influence of this external environment, allows the body to remain within its adaptive capabilities and maintain its health and ability to work. Authors: Fainburg G.Z., Ovsyankin A.D., Potemkin V.I.
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