Section 1. Physiology of labour

1.1. Physiology of labour and comfort conditions of life activity

Classification of human’s activity principal forms. Physical labour and intellectual work. Difficulty and tension of labour. Methods of labour difficulty rating.

Labor activity is divided on physical and intellectual work.

Physical labour is characterized by increased load on supporting-motor apparatus and its functional systems, providing its activity. Physical labour developing the muscular system and stimulating the exchange processes, at the same time has a number of negative consequences. First of all, this is the social inefficiency of the physical labour, connected with its low productivity, necessity of physical powers tension and necessity in the long rest (up to 50% of working time).

Intellectual work joins works connected with information reception and organization that requires the sensory apparatus tension, attention, memory, and also mentation activation, emotional sphere. Hypokinesia is typical for given kind of the labour, i.e. significant reduction of person’s motor activity. Reduction of person’s motor activity results in worsening of organism responsiveness and increasing of emotional tension. Hypokinesia is one of the conditions of cardiovascular pathology formation of the intellectual work persons. Long mental load oppressively influences on psychical activity: the functions of attention, memory, perception get worse.

Labour forms that require significant muscular energy.

This kind of labor operations is used on the absence of mechanized facilities and requires the raised energy expenditures from 17 to 25 MJ (4000 – 6000 kkal) and more per day.

Mechanized labour forms. On these labour forms energy expenditures of workers vary in the range of 12,5 – 17 MJ (3000 – 4000 kkal) per day.

The forms of the mechanized labour change the nature of the muscular loads and complicate the action programmes. Professions of the mechanized labour quite often require the special knowledges and skills.

In conditions of mechanized production it is observed the reduction of the muscular activity volume. Small muscles of distal segments of extremities are involved into the process, which must provide the high speed and accuracy of motions those are necessary on mechanisms control. Monotony of simple and mostly local actions, monotony and small volume of information apperceived in labour, result in the labour monotony.

Forms connected with partly automated production. The Semiautomatic production excludes the person from the process of direct treatment of labour’s object that the mechanisms carry out entirely. Person’s duty is limited by the maintenance of automated lines and electronic technique control. Characteristic features of this kind of work are monotony, increased rate and rhythm of work, taut nerves.

The Physiological particularity of the automated labour forms is a constant readiness of worker to action and reaction rapidity on removal of appearing defects. Such functional condition of "active waiting" is different on degree of fatiguability and depends on attitude to labour, urgency of the necessary action, responsibility of lying ahead work and etc.

Group forms of labour: conveyor. The feature of this form is lies in division of the general process on concrete operations, strict sequence of their execution, automatic giving of the details to each working place by means of moving belt of the conveyor. The conveyor form of the labour requires the synchronous work of participants in accordance with the given rhythm and rate. Herewith than less of time the worker spends on operation, that more monotonous work is and simpler its contents.

Monotony is one of the negative consequences of the conveyor labour, which is expressed in premature weariness and enervation.

Forms of labour, connected with control by production processes and mechanisms. The person is enclosed in control system as necessary operative part - than the control process less automated, that the labour of the person is used. Two main forms of production process control are distinguished from physiological aspect: in one case the control boards require the frequent active actions of the person, but in other case they require the rare active actions. In the first case continuous attention of a worker gets the relaxation in multiple motions and colloquial acts, in the second one the worker is in ready condition to the activity, his reactions are small.

Forms of intellectual (mental) labour. This labour is presented by professions, referring to the sphere of material production, for instance constructors, engineers, technologists, dispatchers, operators and others, and also outside of it: scientists, doctors, teachers, writers, actors, artists and others.

Intellectual labour is concluded in conversion and analysis of the big volume of varied information, and as the result of this - the mobilization of the memory and attention, frequency of stressful situations. However muscular loads, as a rule, small, day power inputs is 10 – 11,7 MJ (2000 – 2400 kkal) per day.

For intellectual labour the hypokinesia is typically i.e. significant reduction of motor activity of the person, resulting in deterioration of organism reactivity and increasing of the emotional voltage. Hypokinesia is a negative production factor, one of the reasons of cardiovascular pathology which have persons of the brainwork. 

In conditions of scientific-technical progress the role of the creative element increases in all spheres of professional activity. At the century of computer technologies the part of mental activity increases in many professions, especially in professions of physical labour, even when the function of control is on the electronic technology.

Mental labour is connected with acceptance and conversion of information, requires the tension of the sensory apparatus, and also the activation of mental processes, emotional sphere.

Forms of mental labour are divided on operator, control, creative labour, the labour medical workers, the labour of teachers and students. They differ according to the organization of the labor process, the evenness of load, emotional tension condition.

Operator’s labour. In conditions of the modern multiple factor production the function of control for functioning of technological lines by processes of turnover and service of buyers are more important. For example, the labour of dispatcher of the wholesale depot or main manager of the supermarket is connected with processing of the big information content for short time period and raised nervously-emotional tension.

Control labour is the labour of leaders of institutions, enterprises is characterized by hyper increase of  information content, quick decision making, increased personal responsibility, periodic occur of conflict situations.

Creative labour is the most difficult form of labor activity, requiring the significant memory capacity, concentration of attention that arise the nervously-emotional tension. This is the labour of teachers, programmers, designers, scientists, writers, composers, actors, artists, architects, constructors.

The labour of the teachers, trade and medical workers, workers of all spheres of service differs by the constant contact with people, raised responsibility, often the deficit of time and information for taking the correct decision that stipulates the high degree of nervously-emotional tension.

The labour of students is the tension of main psychic functions, such as memory, attention, perception; presence of stressful situations (exams, tests).

Energy expenses of a person depend on intensity of the muscular functioning, information intension of labour, degree of the emotional tension and the other conditions (temperature, moisture, velocities of air moving and others). The day expanses of energy for persons of the mental labour (engineers, doctors, teachers and others) are 10,5 – 11,7 MJ; for workers of the mechanized labour and sphere of service (nurses, shop assistants, workers servicing automatic machines) – 11,3 – 12,5 MJ; for the workers, carrying out the work of the medium heaviness (the machine operators, miners, surgeons, melters, agricultural workers and others), - 12,5...15,5 MJ; for workers carrying out the hard physical work (miners, metallurgist, lumbermen, loader), – 16,3 – 18 MJ.

Energy expenses change depending on the working position. In the sitting working position the energy expenses exceed on 5…10 % the level of the main metabolism; in the standing worker position - on 10...25 %, in the forced uncomfortable position - on 40...50 %. During the intensive intellectual work the brain necessity in energy is 15...20 % of the total metabolism in organism (brain mass is 2 % of the body mass). Increasing of the total energy expenses at mental work is defined by degree of nervously-emotional tension. So, during the oral reading in the sitting position the energy consumption increases on 48 %, during the speaking with public lecture - on 94 %, operators of the computers - on 60...100%.

 The level of energy expenses can be the criterion of heaviness and tension of the carried out work, having great meaning for optimization of the labour conditions and its rational organization. The level of energy expenses is defined with the help of the method of the full gas analysis (the volume of the oxygen consumption and isolated carbon dioxide is taken into consideration). With the increase of labour heaviness the consumption of oxygen and amount of applied energy considerably increases.

Heaviness and tension of the labour are characterized by the degree of the functional tension of the organism. It can be energy tension, depending on the labour capability, - at the physical labour, and emotional - at mental work, when information overload occurs.

Physical heaviness of labour is a load on organism at labour, requiring mainly muscular effort and corresponding energy provision. The classification of labour according to the heaviness is carried out on level of energy expenses taking into account the type of load (static or dynamic) and loaded muscles.

Static work is connected with the fixation of instruments and subjects of labour in fixed condition, and also with the giving to a person the working position. So, the work requiring the worker to stay in static pose for 10...25 % of working time is characterized as the work of medium heaviness (energy expenses 172...293 J/s); 50 % and more is the hard work (energy expenses over 293 J/s).

Dynamic work is a process of the muscles anastalsis that results in the moving of load, and also the body of person or his/her parts in space. At that the energy is put out on the keeping of the definite tension in muscles, and also on mechanical effect. If maximum mass of the raised manually loads does not exceed 5 kg for women and 15 kg for men, the work is characterized as light work (energy expenses up to the 172 J/s); 5...10 kg for women and 15...30 kg for men is characterized as medium heaviness work; over 10 kg for women or 30 kg for men is characterized as hard work.

Tension of the labour is characterized by the emotional load on organism during the labour, requiring mainly intensive cerebration on reception and conversion of information. Besides, at the estimation of the tension degree they take into account the ergonomic factors: interchangeability of the labour, position, number of the motion etc. So if the density of perceived signals does not exceed 75 per hour, the work is characterized as light; 75...175 – of medium heaviness; over 176 is characterized as hard work. I In accordance with hygienic classification of the labour the labour conditions subdivide on four classes: 1- optimal; 2 - possible; 3 - harmful; 4 - dangerous (extreme).

Optimal conditions of the labour guarantee maximum productivity of the labour and minimum tension of the organism of the person. The optimal standards are established for microclimate parameters and working process factors. For another factors conditionally use such labour conditions, when the levels of negative factors do not exceed the adopted as the safe factors for population (within the scope of background).

The possible conditions of the labour are characterized by such levels of ambience factors and working process, which do not exceed the adopted ones by hygienic standards for work places. Changes of the functional condition of the organism are restored during the specified rest or to the beginning of the following shift, they must not influence negatively in the near and distant period on the health of worker and his posterity. Optimal and possible classes correspond to the safe labour conditions.

The harmful labour conditions are characterized by the levels of harmful production factors, exceeding hygienic standards and influencing negatively on the organism of worker and (or) his posterity.

The harmful labour conditions (3d level) are divided on four degrees of badness. The first degree (3.1) is characterized by such divergence from hygienic standard, which, as a rule, cause reversible functional changes and condition the risk of disease development. The second degree (3.2) is defined by such levels of production factor, which can cause the stable functional breaches, resulting in the increasing of diseases, temporary loss of ability to work, increasing of the frequency of general diseases, appearance of initial features of professional pathology.

At the third degree (3.3) the influence of harm factor levels results in the development of professional pathology in light forms, growing of chronic general somatic pathology, and also to increasing of diseases level with temporary loss of the ability to works. In conditions of the labour of the fourth degree (3.4) can appear the expressed forms of the professional diseases; it is noted the significant increasing of chronic pathology and high levels of diseases with temporary loss of the ability to works.

The extreme labour conditions are characterized by such levels of production factors, influence of those during the work shift (or its part) creates the danger for life, high risk of the appearing the heavy forms of the sharp professional defeats.

Дата добавления: 2023-11-30