Changes in Organism during a Working Process. Changes in the CNS

The first system reacting to any work is the CNS - its stimulation is marked. At adequate work the favourable changes of the nervous processes are observed, the latent time of reactions is reduced; at extremely hard work a temporary improvement of CNS parameters is replaced by their deterioration resulting in weakening of reflexes, premature exhaustion.

      Changes of Respiration

At work the respiration of organism tissues increases. An increased delivery of oxygen to tissues and removal of СО2 is achieved by increase of respiratory rate and depth (at rest the respiratory rate is 7-22 times per minute, at work - 50 and over, the volume of lung ventilation increases by 5-10 times).

The maximal entry of О2 with respiration is 3-4 l/min – it is the oxygen limit. The entry of oxygen into organism increases gradually and at the beginning of work the oxygen deficit occurs, during which non-oxidized products of metabolism accumulate. At hard inadequate work the oxygen deficit becomes great and several days are necessary for full oxidation of metabolites formed in tissues.

Lingard’s phenomenon. The German physiologist Lingard has established that at hard static physical work a number of people after finishing work require an increased amount of oxygen again due to passing the non-oxidized products of metabolism from tissues into blood that causes stimulation of gas exchange.

      Changes of Cardiovascular System

The increased metabolism in working tissues requires the increase of blood circulation. At work the rate of heartbeat, systolic volume of heart increase; therefore the minute volume of blood increases. Thus, in trained people it increases due to increase of systolic volume, in untrained ones - due to increase of a pulse rate. The arterial pressure, especially maximal one, increases that results in growth of pulse pressure. After adequate work the arterial pressure returns to normal in 5-10 minutes.

The Occupational Harmful Factors and Occupational Diseases. Prevention of Occupational Pathology

The occupational harmful factors (OHF) are factors affecting the working people and capable to cause health disorders, i.e. occupational diseases.

The primary tasks of occupational hygiene in relation to OHF are:

· Studying sources, conditions of occurrence and parameters of OHF at work.

· Studying mechanisms of OHF effect on organism and its systems in experiment with laboratory animals.

· Investigation of cases of occupational diseases at work.

· The development of preventive measures against occupational diseases.

Classification of OHF

In occupational hygiene the following groups of OHF are distinguished:

· OHF connected with non-observance of hygienic conditions in manufacture (non-optimal microclimate, action of harmful occupational factors, etc.);

· OHF connected with improper organization of work (excessively intensive, hard, prolonged work, monotony of work, etc.);

· OHF connected with disadvantages of working conditions (a small area of workplace, a forced position of a body, etc.).

 

According to the State Standard "Dangerous and harmful occupational factors. Classification" all the OHF are subdivided into:

· a dangerous occupational factor which can cause an acute disorder of health or death of a person;

· a harmful occupational factor which can cause a chronic disorder of health – an occupational disease.

 

Classification of OHF in the State Standard is as follows:

· Psychophysiologic and physical factors in the organization of work, arrangement of a workplace and equipment (psychological and physical overloads, a forced position of body, overstrain of separate organs and systems);

· Physical occupational factors (nonoptimal microclimate, illumination, an increased level of noise, vibrations, radiation, electromagnetic fields);

· Chemical occupational factors (industrial poisons) – chemical substances used in manufacture.

· Biological professional factors (microbes, substances of protein nature, allergens);

· Industrial traumatism (mechanical, thermal, electric traumas).

Diagnostics and Prevention of Professional Pathology

The basis of diagnostics and prevention of occupational pathology isthe order ofMinistry of Public Health, including:

· the list of manufactures and occupations which require obligatory preliminary and periodic physical examinations of workers;

· the order of carrying out such examinations, staff of medical commission for the examinations;

· the list of medical contraindications for admission to various kinds of manufacture.

· the list of diagnoses of occupational diseases and poisonings.

Purpose, Types and Organization of Physical Examinations of Workers

Preliminary physical examinations are carried out for newly admitted to work with harmful and dangerous working conditions with the purpose:

· to admit to work only those whose state of health completely meets the requirements of a given profession;

· not to admit to work the persons having deviations in health which can amplify under the influence of working conditions, and also those who can be a source of infections or parasitic diseases.

Periodic physical examinations are regular medical examinations of people working in harmful or dangerous conditions. Their periodicity is determined by order No 45. The aims of these physical examinations are the following:

· to reveal early signs of occupational diseases;

· to reveal common diseases interfering with further work;

· to administer individual medical-prophylactic measures.