Chapter 4. Cell Injury as the Basis for the Development of Various Forms of Human Pathology
15 concise topics with breakdowns: definitions, key facts, and class questions.
Every disease begins at the cellular level. This section is dedicated to the pathophysiology of alteration—from the initial impact of a damaging factor (etiology) to the development of cellular dystrophies and death.
We will sequentially analyze the key links of pathogenesis: impaired energy supply, lipid peroxidation (LPO), ion-water imbalance, membrane and genetic apparatus damage. Special attention is paid to the outcomes of damage (apoptosis, pyroptosis, and other types of cell death) as well as endogenous adaptation mechanisms. The chapter concludes with an analysis of the principles of cytoprotection—from the correction of ion exchange to DNA protection.
Please note: during seminars and exams, instructors most frequently demand strict logic in describing the damage "triad" (energy deficiency, LPO, calcium imbalance), as well as a clear understanding of the differences between apoptosis and necrosis and the molecular basis of pyroptosis. Mastering this chapter is an essential foundation for studying systemic pathophysiology.
This is a medical term denoting cell damage. During alteration, the structure, metabolism, and physicochemical properties of the cell are disrupted, leading to the loss of its normal functions.
How does enzyme function change during cell injury?
Significant activation of hydrolases (lysosomal, membrane-bound, and free) occurs, contributing to the uncontrolled destruction of intracellular structures.
Can a cell suffer from energy deficiency even if ATP is synthesized in sufficient quantities?
Yes, such a scenario is possible. This occurs when transport systems fail (e.g., the enzyme creatine phosphokinase) or when ATPase activity decreases, meaning ready-made energy is simply not delivered to organelles or utilized by them.
Do free radicals always harm the body?
No, under normal conditions they are absolutely essential. They ensure electron transport, phagocytosis, cell division, and the synthesis of important mediators (prostaglandins and leukotrienes).
How does uncompensated acidosis affect cellular enzymes?
It acts as a pathogenic factor that promotes the release of aggressive enzymes (lipases, proteases) from lysosomes. This triggers intensive hydrolysis of the cell's own structures.
Why does a cell swell when damaged?
Due to the accumulation of hydrophilic ions (Na+, Ca2+) and organic substances, intracellular osmotic pressure rises. According to the laws of osmosis, water actively enters the cell, causing it to swell, overstretch, and suffer micro-ruptures of the membranes.
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