3. A role of the reasons and conditions in occurrence of illnesses

Distinguish following etiological factors:

- External or exogenetic (5 groups);

- Internal, or endogenic

External (exogenetic) etiological factors:

Mechanical - influence of the phenomena or the subjects possessing the big stock of kinetic energy, capable at the moment of contact with an organism to cause crisis, a stretching, etc.);

Physical - influence of various kinds of energy: electric (burns, an electroshock, fibrillation of heart), ionizing radiations (beam burns, radiation sickness), thermal factors (high and low temperature - burns);

Chemical - influence of acids, alkalis, poisons of the organic and inorganic nature, salts of heavy metals, hormones, etc.;

Biological - viruses, bacteria ;

Psychogenic - a point of the appendix of these factors is the bark of a brain. They cause iatrogenic diseases (iatros - the doctor; gennao - to create). These diseases develop owing to wrong behaviour of medical workers (" the liver has disappeared " instead of telling " a liver was reduced till the normal sizes "; " not heart, and a cloth " instead of " weak, languid reductions of heart ", etc.).

To "internal" carry hereditary and constitutional factors. A word internal take in inverted commas for finally is also external factors. For example, the principal cause of illness - radiation - has worked on an organism of ancestors in the remote past, has caused changes in the genetic device (mutation) both these changes passed from father to son also everyone new individual it appeared the patient already without dependence from this reason, as the mutant gene (a gene of a hemophilia, albinism, daltonism, etc.), arisen under influence of external influences at ancestors is by right of succession transferred.

2. On intensity of action (I.P.Pavlova's classification) distinguish following etiological factors:

Extreme, or unusual, extreme etiological factors (the big dozes of poison, influence of a lightning, an electric current of a high pressure, falling from the big height, virulent microorganisms, ionizing radiation, etc.);

Usual, but working in unusual quantities and the sizes, i.e. usual by the nature, but leaving on intensity for limits range ща physiological adaptive opportunities of an organism (the insufficient maintenance of oxygen in air, sharp psychoemotional overloads, action of excessively high or low temperatures, etc.);

Indifferent factors is factors, which people do not cause diseases in the majority, but at the some people under certain conditions can become the reason of disease. Allergens concern to them: pollen of plants, colors, a domestic and industrial dust, some antibiotics (penicillin). Action of some indifferent factors is realized on the mechanism of a conditioned reflex. These indifferent influences on all parameters more often the information nature were earlier combined with action on an organism of any pathogenic factor, and after several such combinations on the mechanism of a conditioned reflex such influences can become pathogenic. The similar mechanism underlies attacks of a bronchial asthma, a stenocardia (in reply to the disturbing music combined to attacks, and then only on this music).

Condition is such factor, circumstance or their complex which influencing on an organism, in themselves cause disease cannot, but they influence occurrence, development and current of disease. For example, micobacterium a tuberculosis cause disease not in all people, and only at presence of adverse conditions. Conditions by origin divide on external and internal, and on influence on an organism - on favorable and adverse.

Adverse conditions deepen communication between a cause and effect and promote occurrence of disease (the exhaustion, an insufficient feed, bad living conditions, an emotional - mental pressure, etc.), and favorable, on the contrary, break off cause and effect attitudes and interfere with occurrence of disease (a good feed, a healthy way of life) due to increase of resistency of an organism.

External conditions divide on household, social, natural. It is possible to attributea defective feed, the wrong organization of a mode of day, heat, dampness, a cold to external adverse conditions, etc.

To internal, i.e. connected with an organism, to adverse conditions carry: hereditary predisposition, early children's age, senile age, the pathological constitution.

Internal conditions can be formed in uterinenon lives (for example, decrease in stability of an organism after transferred reproach, pneumonias, diphtherias), to act organism of a fruit during intra-uterine life (alcoholizm, smoking, narcotism at mother during pregnancy), and also to have hereditary character (for example, predisposition to mental diseases, hypertonic illness, a diabetes, a gout, etc.).

Role of the causal factor in occurrence of disease:

- The causal factor is necessary. Any disease has the reason, without it illness cannot arise under any conditions. How the organism has been weakened by previous diseases, but without penetration into an organism of the activator of a dysentery it will not arise. Radiation sickness arises only at influence on an organism ionizing radiation;

- The causal factor is irreplaceable, i.e. cannot be replaced with set of adverse conditions;

- The reason operates directly on an organism, causing this or that consequence - disease, pathological process, a pathological condition. However pathogenic action of the majority of the reasons is realized not directly, and mediatly through interaction with physiological systems of the organism, aspiring to keep a constancy of the internal environment of an organism - a homeostasis;

- The causal factor causes the basic specific features of disease (clinical displays of a virus hepatites essentially differ, more precisely, are absolutely not similar to clinical displays of a stenocardia, epilepsy, pneumonias, etc.).

Role of conditions in occurrence of diseases.

Conditions as well as the reasons are necessary for occurrence of disease, however any of them is not absolutely necessary. Further, conditions widely interchangeable; character of influence of conditions on an organism is various. One conditions can act on an organism directly (a good feed directly raises resistency, stability of an organism), and others can act mediatly (solar beams reduce virulence of micobacterium a tuberculosis and promote recovery of an organism-опосредованное influence).

If the causal factor causes specific features of illness conditions influence differently:

- External conditions operate in frameworks only the given disease, burdening disease or weakening an organism;

- Internal conditions can influence specific displays of illness (depending on internal conditions streptococci in one cases cause a furuncule, in others - a sepsis, in the third - rheumatism).