HUMAN MEDICAL BIOLOGY, ANATOMY, PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

INTRODUCTION

BASICS OF GENERAL PATHOLOGY

Concepts of Health and Disease

In clinical practice, healthcare professionals frequently encounter such concepts as normal body Temperature, normal Blood pressure, and so forth. These typically refer to the average measurement outcomes of specific parameters within a defined population. The most commonly observed values are considered normal, and an individual exhibiting them is deemed healthy. As early as 1946, the World Health Organization defined health as follows: "Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." This rather generalized definition characterizes an ideal to strive for, presenting the desired state as reality.

Health is primarily a state of the Organism characterized by the harmony of Structure and function, alongside the capacity of regulatory mechanisms to maintain a stable internal environment (Homeostasis). Health manifests as adequate, context-specific reactions to daily stimuli in terms of character, magnitude, timing, and duration that align with the Responses of the majority of a given population. Assessments of health are based on anthropometric, morphological, physiological, and biochemical evaluations, while also taking social criteria into account—predominantly an individual's degree of participation in work and social life. The physiological measure of health is the norm.

Disease represents a disruption of the normal vital activity of an organism resulting from the action of damaging factors, which consequently diminishes its adaptive capabilities. A disease involves the coexistence of two opposing processes: the first is the physiological resistance to the illness, and the second, strictly pathological process, is the breakdown. The struggle between these opposing forces constitutes the disease process.

Nosology (from Greek nosos - disease) is the branch of medicine concerned with the Classification and study of diseases. Nosology addresses fundamental questions: what constitutes a disease, how it differs from health, what Causes and Mechanisms drive its development, recovery, or death. Nosology encompasses three major components: Etiology, Pathogenesis, and morphogenesis of disease.

Etiology (from Greek aitia - cause, logos - study) is The Study of the causes and contributing conditions of diseases. Pathologies develop under METABOLISM/18.html">The Influence of a complex set of factors, among which the primary cause of the disease and the conditions of its onset can be distinguished.

The cause of a disease is a pathogenic factor that triggers the illness and determines its specific features. Every disease has a distinct and specific cause. For instance, tuberculosis Bacteria cause a specific pathology—tuberculosis—and without them, the disease cannot develop.

Pathogenic conditions are factors that do not independently cause a specific disease, but heavily promote its onset. Saprophytes (such as Escherichia coli) are present on the Skin, mucous membranes, and in the intestines of all healthy individuals, yet under normal circumstances, they do not cause disease. However, the influence of adverse conditions (such as ionizing radiation or Insulin deficiency) can precipitate severe forms of illness (colitis, furunculosis, stomatitis, etc.).

The causes of diseases can be external (exogenous) and internal (endogenous). Exogenous pathogenic causes include numerous external physical, chemical, biological, psychogenic, and pathogenic factors. Endogenous causes encompass genetic factors and constitutional traits.

Pathogenic conditions may also include climatic and other environmental factors that reduce the body's resistance and enhance the aggressiveness of the disease-causing agent. Social factors play an equally crucial role in disease development.

Pathogenesis (from Greek pathos - suffering, genesis - origin) is the Study of the general patterns governing the development, clinical course, and outcome of a disease. While etiology addresses the causes and conditions of disease onset, pathogenesis investigates everything that transpires following the action of the causative agent. Occasionally, the etiological factor triggers the aggression and then disappears entirely (as seen in trauma, Burns, or ionizing radiation). In such cases, ETIOLOGY AND PATHOGENESIS can be clearly separated chronologically: first etiology, then pathogenesis; first "why," and subsequently "how." Pathogenesis reflects The Essence of damage occurring across various Levels of biological organization, the mechanisms of compensatory-adaptive reactions, and the processes leading to recovery or death. Overall, pathogenesis is viewed as a chain of time-dependent manifestations.

Morphogenesis reflects the dynamics of structural morphological changes throughout the course of a disease, recovery, or death. A disease invariably has some morphological manifestation. The notion of a "functional disease" is explained by the fact that its morphological markers have not yet been identified (for instance, certain psychiatric disorders). This is further evidenced by the fact that the number of recognized "functional" diseases decreases over time.

Various types of tissue damage and adaptive reactions during a disease manifest as deviations of vital activity from the norm. These individual manifestations are termed symptoms, while the aggregate of symptoms characterizing a specific disease constitutes a syndrome.

The clinical course of a disease typically comprises four distinct periods: 1) latent (hidden, incubation) period; 2) prodromal period; 3) period of manifest illness (acme); 4) terminal period.

The latent period (referred to as the incubation period in infectious diseases) spans from the moment of exposure to the pathogenic factor until the appearance of the first clinical signs of the illness. This period can be very brief, as in exposure to chemical warfare agents, or quite prolonged, as in leprosy (spanning several years).

The prodromal period is the timeframe extending from the initial signs of illness to the full development of clinical symptoms. In some cases, this period features vivid clinical presentations (such as lobar Pneumonia or dysentery); in others, symptoms are vague, such as causeless euphoria associated with altitude sickness.

The period of manifest symptoms, or acme, is characterized by the full Development of the clinical picture, featuring specific symptoms and syndromes characteristic of the disease: e.g., Muscle spasms in parathyroid insufficiency, leukopenia in radiation sickness, or the classic triad (hyperglycemia, glucosuria, polyuria) in Diabetes Mellitus patients.

The termination of a disease can take several forms: recovery (complete or incomplete), relapse, transition into a chronic form, or death.

Recovery is The process of restoring disrupted vital Functions and re-establishing normal interactions between the organism and its environment; for humans, this primarily means the restoration of working capacity. Complete recovery leaves no residual traces of the disease, whereas incomplete recovery retains a specific defect—such as a Heart defect—which may nevertheless remain compensated over a long period.

A relapse (recurrence of the disease) is the reappearance of disease manifestations following an apparent or incomplete cessation. This typically occurs when the pathogenic factor (such as a microorganism) was not completely eradicated, but merely suppressed (e.g., in malaria or colitis).

When the body's defense mechanisms are weakened, a disease may become protracted; its acute manifestations subside, but complete recovery fails to occur, leading to a chronic course. Chronic diseases are characterized by alternating periods of exacerbation and remission. Remission is a temporary improvement in the patient's condition, manifested by the partial or complete disappearance of clinical symptoms. However, this improvement is typically followed by a disease flare-up (relapse). Remissions can last anywhere from a few days to several years. Ultimately, the disease may culminate in disability or the patient's death.