18 Questions
What is the characteristic feature of apoptosis in terms of cell size?
Reduced
Which type of cell death is always pathologic?
Necrosis
What is the fate of apoptotic cells or cell bodies?
They are rapidly phagocytosed by macrophages
Which of the following is a characteristic of apoptosis morphology?
Chromatin condensation and fragmentation
What is the type of cell death that is characterized by active, programmed cell death?
Apoptosis
Which type of apoptosis is involved in the removal of excess cells during embryonic development?
Physiologic apoptosis
What is the primary mechanism of apoptosis?
Programmed cell death
What is the characteristic appearance of fibrinoid necrosis under microscopy?
Fibrin-like, structure-less and bright pink
Which of the following is a physiological example of apoptosis?
Regression of the lactating breast
What is the purpose of apoptosis in maintaining homeostasis?
To maintain a constant number of cells
What is the result of apoptosis in the context of embryogenesis?
Removal of unwanted cells
What is the difference between apoptosis and necrosis?
Apoptosis is active, while necrosis is passive
What is the difference between apoptosis and necrosis?
Necrosis is an accidental cell death, whereas apoptosis is a programmed one.
What is the characteristic of apoptosis in terms of energy?
Energy-dependent
What is the term for the fragmentation of the nucleus during apoptosis?
Karyorrhexis
What is the term for the shrinkage of the nucleus during apoptosis?
Pyknosis
What is the term for the dissolution of the nucleus during apoptosis?
Karyolysis
What is the characteristic of necrosis in terms of programming?
Non-programmed cell death
Study Notes
Types of Necrosis
- Fat necrosis: occurs due to trauma to adipose tissue of breast and subcutaneous tissue, causing rupture of fat cells with self-digestion, resulting in a firm white areas
- Fibrinoid necrosis: a special form of necrosis typically seen in immune reactions involving blood vessels (vasculitis), characterized by deposits of “immune complexes” and fibrin that has leaked out of vessels in the walls of arteries
Fibrinoid Necrosis
- Microscopic appearance: homogeneous, eosinophilic (bright pink) and structure-less, resembling fibrin
- Example: fibrinoid necrosis in an artery
Apoptosis
- Definition: programmed cell death, also known as cell suicide, where individual cells or a small group of cells die within the living body to remove unwanted cells
- Characteristics: energy-dependent, active, and programmed
- Physiological causes:
- During embryogenesis
- Hormone-dependent (e.g., shedding of endometrium in menstrual cycle, regression of lactating breast)
- Cell loss in proliferating cell populations (homeostasis)
- Elimination of potentially harmful self-reactive lymphocytes
- Death of cells that have served their useful purpose (e.g., neutrophils at the end of acute inflammation)
- Pathological causes:
- DNA damage (e.g., radiation, anticancer drugs)
- Pathological atrophy (e.g., organ obstruction)
- Cell death in infections (e.g., viral infections)
- Cell death by cytotoxic T lymphocytes
- Morphology:
- Cell shrinkage
- Chromatin condensation and fragmentation
- Formation of cytoplasmic blebs and apoptotic bodies
- Rapid phagocytosis of apoptotic cells or cell bodies by macrophages
- No inflammation
Comparison of Necrosis and Apoptosis
- Necrosis: passive, non-programmed, affects a large group of cells, enlarged cells, pyknosis, karyorrhexis, and karyolysis, with adjacent inflammation
- Apoptosis: active, programmed, affects a single cell or small group of cells, reduced cell size, chromatin condensation and fragmentation, with no inflammation
Cell Response to Injury
- Causes of cell injury: depends on the type of injured cells, irritant nature, severity, and duration
- End result of injury: reversible (cloudy swelling, hydropic swelling, fatty change) or irreversible (necrosis, apoptosis)
This quiz covers the process of cell death through apoptosis, including the role of viral infections and cytotoxic T-cells, and the morphological changes that occur during this process.
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