Subject and tasks of pathophysiology

Tasks and structure of the discipline

Pathological physiology addresses fundamental tasks that form the basis of a physician's clinical thinking. First, it establishes the very essence of disease. Second, it studies in detail the causes and conditions for the onset of a disorder. Third, it reveals the subtle mechanisms of the origin, development, course, and outcome of a disease. Fourth, based on the data obtained, it determines the principles of prevention and treatment.

This science connects fundamental subjects — anatomy (body structure in relation to its functions and environmental impact) and physiology (normal life processes) — directly with the clinic. Traditionally, the subject is divided into three major sections:

1. General nosology — the fundamental, general doctrine of disease, health, and transitional states.
2. Typical pathological processes — standard reactions of the body. These include inflammatory and adaptive processes, cell damage, pyroptosis, tumor progression, and other stereotyped changes (e.g., edema).
3. Pathophysiology of organs and systems (systemic pathophysiology) — the study of specific functional disorders. For example, the pathophysiology of the leukocyte or platelet system, circulatory pathology, or nervous system disorders (including such manifestations as peripheral, flaccid, spastic, and rigid paralysis).

Fundamentals of nosology: etiology and pathogenesis

For an in-depth analysis of disease, pathophysiology operates with a rigorous conceptual apparatus. The two foundational doctrines are etiology (concerning the causes and conditions of disease development, including the causes of congenital malformations) and pathogenesis (concerning the mechanisms of development of a pathological process).

When studying pathogenesis, researchers invariably search for the main link of pathogenesis — that specific process which is critically necessary for the unfolding of all other pathological phenomena. Frequently, in the course of a disease, a vicious circle of pathogenesis is formed. It arises due to a shift in cause-and-effect relations, where the consequence itself begins to act as a cause, aggravating the severity of the condition. Knowledge of these mechanisms allows physicians to apply pathogenetic therapy — treatment that purposefully eliminates the mechanisms of disease development, rather than just its symptoms.

In addition, general nosology distinguishes between such concepts as:

• Norm and health.
• Pre-disease — transitional states of the body between health and disease.
• Pathological reaction, pathological state, and pathological process.

Nosology also examines the stages and outcomes of disease, mechanisms of recovery, and compensatory, protective, and restorative reactions of the body.

Experiment and animal modeling

The primary method by which pathophysiology explores functional changes in a diseased organism is the experimental method. In practice, it is implemented through disease modeling.

During experimental research, physicians and researchers master specific techniques for working with laboratory animals. For example, fixation in special frames and anesthesia administration techniques are practiced according to strict protocols:

• Mice are injected subcutaneously with 0.20 ml of a 1.00% hexenal solution.
• Frogs receive 0.50 ml of a 20.00% urethane solution into the back skin.
• Inhalation ether anesthesia is used for rats.

Solution administration routes are also practiced (for example, 0.40 ml of saline can be administered to a rat intramuscularly, subcutaneously, intraperitoneally, or intravenously) and blood sampling — 0.50 ml from the marginal ear vein of a rabbit or 0.20 ml from the tail vein of a rat. Surgical modeling is also practiced, such as a splenectomy in a rat involving an aponeurosis incision, opening of the peritoneum, vessel ligation, and layered suturing.

Modeling has its opportunities and limitations. Paramount importance is attached to the comparative-evolutionary approach in interpreting experimental data, as well as the moral and ethical aspects of working with animals and strict deontological rules for human research.

The foundations of the experimental approach and the entire discipline were laid by prominent Russian scientists: I. M. Sechenov, I. P. Pavlov, S. P. Botkin, V. V. Pashutin, A. V. Focht, A. A. Bogomolets, N. N. Anichkov, V. V. Voronin, N. N. Sirotinin, A. M. Chernukh, P. D. Gorizontov, I. I. Mechnikov, A. D. Ado.

Class and exam questions

What else to study on this topic

• Disease modeling: types, opportunities, limitations, and moral-ethical aspects
• Transitional states of the body: norm, health, and pre-disease
• Mechanisms of recovery (sanogenesis) and disease outcomes
• Protective, compensatory, and restorative reactions of the body
• Historical stages of pathophysiology development and the contribution of Russian scientists

Other topics in the "Additional Topics" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.