Stage of adaptive mechanism failure
At this stage, the body's defense and compensatory reactions lose their effectiveness, while the damaging effect of the extreme factor increases. Functional systems disintegrate, metabolism is disrupted, plastic processes are inhibited, and cellular and tissue structures are damaged. Most homeostasis parameters deviate critically from the norm.
Due to the overstrain of adaptive mechanisms, vital organs and systems suffer:
- Nervous system: disorders of sensitivity, movement, integration, and higher nervous activity.
- Cardiovascular system: arrhythmias, ischemia, heart failure, and capillariotrophic failure.
- Blood system: deterioration of blood flow and viscosity, aggregate formation, sludge phenomenon, and thrombohemorrhagic complications.
Pathological vicious circles
Under conditions of adaptation failure, pathological closed complexes (circulus vitiosus) are formed. The initial factor triggers a cascade of disorders that, via positive feedback, intensify the root cause.
Main examples of such processes:
- Hemodynamic failure: inadequate vasodilation and blood pooling lead to a drop in circulating blood volume, reduced venous return and cardiac output, which further decreases the circulating blood volume.
- Cellular level: hypoxia and suppression of antioxidant defense stimulate lipid peroxidation (LPO) and the accumulation of reactive oxygen species. This damages respiratory and glycolytic enzymes, exacerbating tissue oxygen starvation.
Multiple organ disorders and homeostasis
The development of pathology leads to profound multiple organ damage:
- Kidneys: filtration and secretion are impaired, oliguria or anuria develops, progressing to uremia.
- Liver: protein, fat, and carbohydrate metabolism, detoxification function, and the blood coagulation system suffer.
- Gastrointestinal tract: motility and secretion are inhibited up to the point of paresis, malabsorption, intestinal autoinfection, and autointoxication develop.
Critical deviations of homeostasis parameters include a drop in $pO_2$, acidosis, blood pressure surges, and ion imbalance.
Stage of extreme life support regulation
Upon depletion of energy resources and deepening deafferentation of central and peripheral structures, the terminal stage ensues. Functional systems disintegrate completely, and the organism shifts to a primitive metabolic level of regulation.
- Without treatment: the progression of disorders leads to a terminal state and death.
- With effective therapy: the pathological process can be blocked, restoring the normal state of the organism.
Order of destruction: first Adaptation fails, Vicious circles form within it, Organs suffer (multiple organ dysfunction), after which regulation drops to the Metabolic level.
Class and exam questions
What are pathological vicious circles in pathophysiology?
These are closed complexes of disorders where the consequences of the pathological process amplify the initiating factor via positive feedback, exacerbating the severity of the condition.
What respiratory disorders are characteristic of the adaptation failure stage?
In severe cases, periodic breathing patterns develop — Biot, Cheyne-Stokes, Kussmaul breathing, and in extremely severe cases, complete cessation of breathing (apnea) occurs.
What are the consequences of renal dysfunction at the stage of multiple organ disorders?
Filtration, excretion, and secretion processes are impaired, manifesting as oliguria or anuria and leading to varying degrees of uremia.
What else to study on this topic
- Mechanisms of sludge phenomenon formation and thrombohemorrhagic states
- Biochemical targets of reactive oxygen species during cellular hypoxia
- The role of liver failure in blood coagulation disorders
- Pathogenetic features of Kussmaul, Biot, and Cheyne-Stokes respiration
- Dynamics of changes in central and peripheral hemocirculation
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