Types of reactivity by response intensity
The body's response to a stimulus is assessed by quantitative and qualitative adequacy. Four main types are distinguished:
- Normoergy — a quantitatively and qualitatively adequate response to the agent's impact.
- Hyperergy — an excessive response to a stimulus. A striking example is the development of anaphylactic shock upon re-entry of an antigen into the bloodstream.
- Hypoergy — an inadequately weak response to the impact. It is often observed in various immunodeficiencies, when an ineffective immune response to a foreign antigen is formed.
- Anergy — the complete absence of the body's reaction. This type indicates severe disturbances in vital activity (for example, the absence of a response to a pain stimulus in a comatose patient).
Specificity and immunogenicity
Depending on the degree of response differentiation, reactivity is divided into two large groups:
- Specific — occurs in response to a strictly defined antigen. This category includes the classical immune response and allergic reactions.
- Nonspecific — a reaction to diverse factors without strict specificity. The main mechanism here is the activation of the leukocyte phagocytic response. Foreign cells, inorganic particles, bacteria, viruses, and parasites can act as triggers.
Also, immunogenic reactivity (changes in vital activity caused by antigenic factors) and non-immunogenic reactivity (changes in vital activity under the influence of agents that do not possess antigenic properties, such as psychological, physical, chemical, or biological factors) are distinguished.
Physiological and pathological reactivity
Reactivity can be both beneficial and destructive in nature:
- Physiological reactivity is always adequate to the nature and intensity of the impact. It has an adaptive significance, meaning it is beneficial to the body. An example is normal immunity.
- Pathological reactivity is characterized by the inadequacy of the response in terms of intensity or character. It is always accompanied by a decrease in the body's adaptive capabilities.
Individual pathological reactivity is considered separately — this is an inadequate reaction in individual persons to factors that do not cause any response in the majority of people. A classical example is the development of allergic reactions to ordinary household stimuli, food products, or pollen.
Role in pathogenesis and principles of therapy
Pathogenesis is a complex of interrelated processes of damage and adaptation underlying the development and outcomes of diseases. General pathogenesis (studies general patterns and formulates treatment principles) and particular pathogenesis (the mechanism of development of a specific nosological form) are distinguished.
Etiology (the cause) often operates on the "switch" principle: the pathogenic factor acts as a trigger, initiating the initial link of pathogenesis. Next, a branched chain of cause-and-effect relationships is formed, and the process develops without further need for the presence of the cause.
Understanding reactivity allows for building medical tactics:
- Preventive measures are aimed at identifying the cause, suppressing risk factors, and activating the immunobiological surveillance system (for example, the use of immunomodulators).
- Therapeutic measures are applied when the agent is already acting on the body. Their goal is to stop or reduce the intensity of the agent's action (the use of antimicrobial agents in infections, stopping bleeding and transfusing blood substitutes in vascular trauma).
Briefly: answers to topical questions
What stages (periods) are distinguished in the development of a disease?
Four main stages are distinguished in the development of a disease.
- Latent stage (latency, incubation) — the period of covert development from the moment of exposure to the pathogenic agent until the appearance of the first signs.
- Prodromal stage (period of precursors).
- Stage of pronounced manifestations (height of the disease, manifestation of specific signs).
- Outcome of the disease.
What types of anergy exist?
Two variants of anergy, which represents the absence of a reaction to the pathogen, are distinguished.
- Positive (protective) — is the result of the body's refractoriness (for example, as the goal of vaccination and immunity enhancement).
- Negative (pathological) — occurs as a result of the exhaustion of adaptive and compensatory capabilities, which leads to the complete defenselessness of the body.
How to easily remember the types of reactivity by intensity: focus on the prefixes. Normo- (normal response), Hyper- (excessively strong), Hypo- (weak), An- (complete negation, absence of response).
Class and exam questions
What is individual pathological reactivity?
This is an inadequate reaction of a specific person to ordinary stimuli that do not cause such a response in the majority of people (for example, the development of an allergy to pollen).
What is the essence of the "switch" principle in pathogenesis?
The pathogenic factor acts as a trigger. It launches the initial link of pathogenesis, after which a chain of cause-and-effect relationships is formed, and the pathological process develops independently, even without the presence of the cause.
What is the difference between hypoergy and anergy?
In hypoergy, the reaction to the stimulus is present, but it is inadequately weak (for example, in immunodeficiencies). In anergy, the body's response is completely absent, which indicates severe disturbances in vital activity (for example, the absence of a response to pain in a coma).
What else to study on this topic
- Mechanisms of the leukocyte phagocytic response
- Immunobiological surveillance (IBS) system and immunomodulators
- Etiotropic prevention and risk factor management
- General and particular pathogenesis: key differences
- The initial link of pathogenesis and cause-and-effect relationships
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