Pathogenesis at the Cellular Level
Cellular injury is rooted in the disruption of neurohumoral regulation mechanisms resulting from deviations in homeostasis parameters. There are four main pathogenetic pathways leading to cell death or dysfunction:
- Imbalance of Biologically Active Substances (BAS). This leads to inefficient consumption of oxygen and metabolic substrates, creating an acute deficit in tissues.
- Cellular Hyperfunction. Working to the point of exhaustion inevitably culminates in dystrophy and dysplasia.
- Calcium Overload. Excess intracellular calcium ions trigger the calcium triad of structural damage.
- Catabolic Surge. Excessive activation of hydrolases, free radicals, and lipid peroxidation (LPO) destroys cell membranes, enzymes, and nucleic acids.
The ultimate result of these processes is a global disruption of plastic processes and overall viability of the organism.
Biochemical Shifts and Resource Mobilization
Pathogenic changes are closely linked to an endocrine storm. The blood concentrations of catecholamines, glucocorticoids, antidiuretic hormone (ADH), and growth hormone (GH) sharply increase.
At the cellular level, this hormonal cocktail provokes hyperactivation of lipases and phospholipases, alongside massive generation of reactive oxygen species. Consequently, lipid components of membranes and their associated enzyme complexes are damaged, and transmembrane processes collapse.
High levels of stress hormones cause excessive mobilization of proteins, fats, and carbohydrates. This process has a dual nature:
- Adaptive effect: emergency supply of substrates to dominant functional systems.
- Pathogenic effect: during a prolonged reaction, reserves are depleted, leading to dystrophy and necrosis in both hyperfunctioning and resting tissues.
Circulatory Centralization and Immune Failure
During severe, prolonged, or repeated stress, the body sacrifices the periphery to preserve vital centers. The phenomenon of blood flow redistribution develops: perfusion of the heart and brain increases, while the skin, kidneys, and gastrointestinal tract (GIT) suffer from ischemia. This hypoperfusion is the primary cause of "stress ulcers" and erosions.
Chronic stress also strikes the immune surveillance system. Its effectiveness drops, while nucleic acid and protein synthesis are activated. This combination—weakened genetic control coupled with active gene expression—creates a favorable environment for the activation of oncogenes and tumor progression.
Two Scenarios: Adaptation or Pathology
Depending on the biological significance, intensity, and duration of the exposure, the stress response can follow one of two paths:
- Adaptive Reaction. Occurs with moderate exposure. Homeostasis is preserved, and the body acquires a state of increased resistance. Cross-non-specific adaptation develops, where resistance increases not only to the initial stressor but also to other aggressive factors. This principle is utilized in conditioning therapies (measured physical exertion, hypobaric hypoxia, autohemotherapy, thermal exposures).
- Pathogenic Reaction. Develops during excessively strong, frequent, or prolonged exposure when the body cannot maintain homeostatic parameters. Adaptation fails, manifesting as severe metabolic and functional disorders, extreme states (shock, collapse, coma), and a risk of transitioning to a terminal stage.