12 topics with brief reviews: definitions, key facts, and seminar questions.
Any pathological process affects cells in one way or another, and the extreme degree of their damage is cell death. In this section, we examine two fundamental scenarios of cell death: "violent" necrosis and programmed apoptosis.
Here you will find all the fundamentals on the topic: from etiology and pathogenesis to macro- and microscopic presentation. You will study the classification of clinical and morphological forms of necrosis, the mechanisms and morphology of apoptosis, and get acquainted with specific types of cell death. Special attention is paid to outcomes—both favorable (organization, petrification) and unfavorable.
What is most commonly asked in classes? Instructors love asking to compare necrosis and apoptosis based on microscopic and biochemical features. Also, be prepared to confidently differentiate the clinical and morphological forms of necrosis (infarction, gangrene, sequestrum, pressure ulcer) and explain the consequences of dysregulated apoptosis in tumor growth or neurodegeneration.
What is the main difference between necrosis and apoptosis?
Necrosis is the result of external injury ("murder"), while apoptosis is the execution of an internal genetic program ("suicide").
What is the difference between necrosis and somatic death?
Necrosis is the death of only a part of the organism, whereas somatic death means the cessation of life of the entire organism as a whole.
Why are calcium ions considered the key mediator of irreversible cell injury?
$Ca^{2+}$ ions activate Ca²⁺-dependent phospholipases, proteases, and endonucleases, which destroy membrane phospholipids, cytoskeletal proteins, and nucleic acids, driving the injury into an irreversible stage.
What tissue changes are visible in the early stages of necrosis?
At early stages, the necrotic process is usually invisible to the naked eye and under light microscopy.
Why does the cytoplasm become bright pink in necrosis when stained with hematoxylin and eosin?
Increased eosinophilia occurs due to the binding of eosin to denatured cytoplasmic proteins and the loss of basophilia associated with the disappearance of ribosomal RNA.
What is the role of C-reactive protein in necrosis?
CRP is synthesized in the liver, accumulates in necrotic masses, and activates the complement system via the classical pathway. This is necessary to initiate demarcation inflammation.
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