20. Reactivity. Types. Dependence on sex.

Reactivity is an organism and his structures respond to environmental factors action with vital activity changings.

Role: it defines organism interaction with surrounding world. It influences greatly on diseases development and course.

Examples at different organizational levels (to question N.22):

1. molecular – oxyhaemoglobine dissociation curve movement to the right under acidosis caused by hypoxy (Bor’s effect);

2. cellular – microbic phagocytosis with leucocytes;

3. tissular – inflammation development after injuring factors action;

4. organic – heart beating rate increasing at blood temperature increasing;

5. systemic- external respiration, blood circulation reaction in blood at oxygen fasting;

6. organismic –complex oriented reactions as answer to sound and light signals action.

Reactivity types:

1. 1) Species – is a characteristics of all individuals belonging to a given species;

2) group – of individuals belonging to 1 group;

3) individual – of 1 separate organism.

2. 1) Non-specific (primary, simple) –is expressed at different factors influencing on organism; its base is answer genetically-programmed standard variants (example – protective-compensatory reactions at high and low temperatures action, at oxygen fasting, phagocytosis);

2) specific – immunological reactivity.

3. 1) Physiological – is actual in healthy organism;

2) pathological – qualitatively changed reactivity at pathogenic factors action.

4. 1) Increased (hyperergia);

2) decreased (hypoergia).

Factors influencing on reactivity:

23. Age – children have low reactivity; it is gradually is increased up to adult age, then is decreased in the old people.

24. Sex.

25. Heredity.

26. Functional state of nervous, endocrine, immune systems and connective tissue.

27. Environmental factors – climate, feeding character, social conditions et al.

Reactiveness main indexes:

1. Non-specific reactivity: 1.Irritability.

2.Excitability.

3.Sensitivity (to pain, heating, coldness, of sense organs et al.).

4.General adaptation syndrome development speed and intensivity (it is considered that men are more resistant to acute stress, women – to chronic one).

5.Ability to respond to the stimulus action with adrenaline secretion enforcement, tachycardia, hypertension (is higher in men comparatively to women).

2. Specific reactivity:

1. Antibodies formation velocity and intensivity (according to several data, it is higher in men than in women).

2. Immunoglobulines types.

23. Resistance. Passive and active resistance. Resistance and reactivity relationship.

Resistance is an organism resistance to pathogenic factors action.

Types:

1. Passive – non-sensitivity to pathogenic factor action, imperceptibility to them. It appears when organism interaction with pathogenic factor is impossible or hardened (complicated). Passive resistance is energy-independent. It can be determined by following mechanisms:

   1. barriers existence for pathogenic factor interaction with organism structures (biological barriers);

   2. absence or decomposition of organism structures capable to interact with pathogenic factor (for instance, receptors absence to pathogenic viruses);

   3. pathogenic factor destroying with mechanisms which are not delt with organism reaction to the action of this factor (for example, cholera vibrion decomposition with gastric juice);

   4. pathogenetic mechanisms realization retardation when these ways are triggered by organism interaction with pathogenic factor (for example, passive resistance increasing at hypothermia).

2. Active – resistance provided by complex of protective-compensatory reactions directed to pathogenic factor destroying as well as results of its action. This resistance is energy-dependent. Reactivity mechanisms are its base (for example, phagocytosis, antibodies production, cellular immunity reactions).

Reactivity and resistance interrelations (variants):

1. Reactivity increasing causes active resistance rising up. For example, at body temperature increasing antibodies synthesis is activated which increases active resistance to the infections.

2. Reactivity increasing causes active resistance decreasing. So, antibodies production increasing can be allergy reason at which organism resistance is decreased to antigens action.

3. Reactivity decreasing leads to active resistance decreasing. For instance, antibodies synthesis decreasing reduces active resistance to the infections.

4. Reactivity reducing is accompanied by passive resistance increasing. So, at hypothermia passive resistance to the infections, intoxications and other pathogenic factors action is increased (for instance, at winter anabolism in animals).

24. NON-SPECIFIC RESISTANCE MECHANISMS. CELLS UNDERACTIVITY. NON-SPCIFIC RESISTANCE PHYSICAL AND CHEMICAL FACTORS.

Mechanisms of non-specific resistance providing organism resistance to infectious agents action

1. Cellular areactivity.

2. Physical and physical-chemical factors.

3. Biological barriers.

4. Antagonistic interrelations between normal and pathogenic microflora.

5. Connective tissue physiological system functioning.

6. Non-specific resistance humoral factors.

7. Phagocytosis.

8. Inflammation.

Cellular areactivity – cells non-ability to interact with infectious agent. It can be determined by:

1. absence of receptors to viruses on cellular surface;

2. absence of receptors to bacterial toxins in cells;

3. toxin binding with cells receptors which are non-resistant to its action (receptors scanning).

Physical and physical-chemical factors of non-specific organism resistance to infections:

1. Temperature – temperature level in birds provides their resistance to anthrax causative agent. At body temperature increasing reproduction of many viruses is disturbed and they die.

2. Environment pH level – many causative agents of infectious diseases (particularly vibrio cholerae) die in stomach acid environment. Hydrogen ions high concentration is created in inflammation focus. It causes microorganisms injury here.

3. Oxygen tension in tissues. PO₂ is so under normal conditions that prevents anaerobic infections development.