Cell Swelling (Morphological Features of Cell Injury)
Early sign of reversible cell injury due to the influx of water and ions (mainly sodium).
Causes
Malfunction of energy-dependent ion pumps caused by hypoxia, toxins, or other disruptions to energy production.
Microscopy
Enlarged, pale, and turgid cells.
Outcome
Reversible if the stressor is removed; may progress to irreversible injury and cell death if persistent.
Intracellular Accumulation
Abnormal build-up of substances within the cell, which can be endogenous (proteins, lipids, carbohydrates) or exogenous (infectious agents, minerals, pigments).
Examples
I. Fatty Change: Lipid accumulation.
II. Hyaline Change: Protein accumulation.
III. Hemosiderin Deposition: Iron accumulation.
Outcome
Can cause cellular dysfunction, injury, or death depending on the nature and severity of the accumulation.
Calcification
Types
A. Dystrophic Calcification: Localized deposition in injured or dead tissues, such as necrotic areas, heart valves, or atherosclerotic plaques. Not related to calcium metabolism disturbances.
B. Metastatic Calcification: Occurs in normal tissues due to hypercalcemia or calcium metabolism disturbances, affecting organs like kidneys, lungs, blood vessels, and stomach.
Outcome
Impairs organ function and may lead to further tissue injury or inflammation.
Enzyme Leakage
Release of intracellular enzymes into the extracellular space or circulation due to cell membrane damage.
Causes
Mechanical trauma, toxins, ischemia.
Clinical Relevance
Measurement of specific enzymes in the blood (e.g., creatine kinase for myocardial infarction, alanine aminotransferase for liver injury) helps diagnose and monitor tissue damage.
Outcome
Indicator of cell injury or death, reflecting loss of membrane integrity.
Cell Death
Form
A) Apoptosis
Programmed cell death involving caspase activation.
Features: Cell shrinkage, chromatin condensation, nuclear fragmentation, formation of apoptotic bodies, and phagocytosis by neighboring or immune cells.
Outcome: Typically, does not induce an inflammatory response
B) Necrosis
Unregulated cell death due to severe injury or membrane damage.
Features: Cell swelling, membrane rupture, leakage of cellular contents, and inflammation in surrounding tissues.
Subtypes: Coagulative necrosis and others with distinct morphological features.
Outcome
Final consequence of irreversible cell injury.
