Cell Death: Necrosis and Apoptosis
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Cell Death: Necrosis and Apoptosis

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Questions and Answers

What causes fat necrosis in adipose tissue?

  • Enzyme action of lipases (correct)
  • Bacterial infection
  • Cellular apoptosis
  • Oxygen deprivation

    • What is indicated by the presence of chalky white areas in fat necrosis?

  • Chronic infection
  • Fat saponification (correct)
  • Cellular apoptosis
  • Vascular inflammation

    • Which condition is typically associated with fibrinoid necrosis?

  • Chronic obstructive pulmonary disease
  • Osteoarthritis
  • Malignant hypertension (correct)
  • Diabetes mellitus

    • Which feature distinguishes apoptosis from necrosis?

    <p>intact cell membrane</p> Signup and view all the answers

    How does physiological apoptosis function in tissue maintenance?

    <p>It eliminates unneeded cells</p> Signup and view all the answers

    What is a characteristic of pathological apoptosis?

    <p>It prevents collateral tissue damage</p> Signup and view all the answers

    What is a common example of physiological apoptosis during hormonal changes?

    <p>Endometrial breakdown during the menstrual cycle</p> Signup and view all the answers

    Which microscopic feature is associated with fibrinoid necrosis?

    <p>Thickened and pinkish-red vessel walls</p> Signup and view all the answers

    What is the primary characteristic of necrosis?

    <p>Death of a group of cells accompanied by inflammation.</p> Signup and view all the answers

    Which of the following is NOT a type of necrosis?

    <p>Apoptotic Necrosis</p> Signup and view all the answers

    What is a hallmark feature of coagulative necrosis?

    <p>Cell outlines remain, but organelles are destroyed.</p> Signup and view all the answers

    What morphological feature is associated with necrotic cells?

    <p>Necrotic cells are eosinophilic and may be vacuolated.</p> Signup and view all the answers

    Which of the following is a cause of necrosis?

    <p>Hypoxia</p> Signup and view all the answers

    During necrosis, what happens to the nuclear structure?

    <p>Nucleus undergoes karyorrhexis or karyolysis.</p> Signup and view all the answers

    What defines apoptosis as a process of cell death?

    <p>Involves programmed cellular events.</p> Signup and view all the answers

    Which type of necrosis is most common and occurs due to ischemia?

    <p>Coagulative Necrosis</p> Signup and view all the answers

    What is a characteristic feature of coagulative necrosis in the kidney?

    <p>Wedge-shaped kidney infarct</p> Signup and view all the answers

    In liquefactive necrosis, which of the following is most commonly seen?

    <p>Liquidy and creamy yellow tissue</p> Signup and view all the answers

    Which type of necrosis is associated with a 'cottage cheese-like' appearance grossly?

    <p>Caseous necrosis</p> Signup and view all the answers

    What type of cellular changes are observed in necrotic cells during coagulative necrosis?

    <p>Pyknosis and karyorrhexis</p> Signup and view all the answers

    Which cellular component predominantly infiltrates areas of necrosis during liquefactive necrosis?

    <p>Neutrophils</p> Signup and view all the answers

    What histological feature is commonly associated with caseous necrosis?

    <p>Cellular debris surrounded by granulomatous inflammation</p> Signup and view all the answers

    What often results from bacterial infections leading to liquefactive necrosis?

    <p>Release of proteolytic enzymes</p> Signup and view all the answers

    What is typically observed microscopically in coagulative necrosis?

    <p>Loss of cellular outlines with preserved shape</p> Signup and view all the answers

    What is a characteristic feature of apoptosis?

    <p>Membrane blebbing</p> Signup and view all the answers

    Which protein is considered pro-apoptotic?

    <p>Cytochrome c</p> Signup and view all the answers

    What typically triggers apoptosis related to the accumulation of misfolded proteins?

    <p>Infections</p> Signup and view all the answers

    Which of the following differences pertains to necrosis compared to apoptosis?

    <p>Necrosis involves groups of cells</p> Signup and view all the answers

    Which enzymes are primarily activated during apoptosis?

    <p>Proteases and endonucleases</p> Signup and view all the answers

    In apoptosis, what happens to the nucleus?

    <p>It condenses and fragments</p> Signup and view all the answers

    What type of response occurs during necrosis?

    <p>Inflammatory response</p> Signup and view all the answers

    What is the fate of apoptotic bodies?

    <p>They are phagocytosed by neighboring cells</p> Signup and view all the answers

    Study Notes

    Cell Death: Necrosis and Apoptosis

    • Necrosis is caused by irreversible cell injury leading to enzymatic digestion of dead cellular components.
    • Apoptosis is programmed cell death and is a vital process eliminating unwanted cells through an internally programmed series of events.

    Types of Necrosis

    • Coagulative Necrosis is the most common type of necrosis, usually results from ischemia (loss of blood supply).
      • It is most commonly seen in solid organs, such as heart, kidneys, and spleen.
      • Grossly: Tissue is firm, often wedge-shaped, and pale.
      • Microscopically: The outlines of the cells are retained, but cytoplasmic and nuclear details are lost.
    • Liquefactive Necrosis results from enzymatic lysis of cells and proteins.
      • Mainly due to the action of proteolytic enzymes released from targeted cells, liquefying the tissue.
      • Most often seen in brain infarction and localized bacterial infections (abscesses).
      • Grossly: Tissue is liquidy and creamy yellow due to pus formation.
      • Microscopically: Lots of neutrophils and cell debris.
    • Caseous Necrosis is characterized by a "cottage cheese-like" appearance.
      • Seen in tuberculosis lesions and fungal infections.
      • Grossly: Soft and friable necrotic tissue.
      • Microscopically: Loss of cell outlines, nuclei, and acellular pink areas of necrosis with cellular debris surrounded by a granulomatous inflammatory process.
    • Fat Necrosis occurs specifically in adipose tissue due to the action of lipases.
      • This generates chalky white areas called fat saponification due to the deposition of calcium.
      • Grossly: Chalky, white areas.
      • Microscopically: Shadowy outlines of dead fat cells, surrounded by basophilic calcium deposits and an inflammatory reaction.
    • Fibrinoid Necrosis is a specific type of necrosis seen in immune reactions involving blood vessels.
      • Immune complexes and fibrin get deposited in vessel walls.
      • Grossly: Changes are usually too small to see grossly.
      • Microscopically: Vessel walls are thickened and pinkish-red.
      • Seen in malignant hypertension and vasculitis.

    Apoptosis

    • Apoptosis is a programmed cell death where the cell membrane remains intact.
    • It is an energy-dependent process eliminating unwanted cells without an inflammatory response.
    • It is characterized by protein cleavage within the cell, causing cellular death.

    Physiological Apoptosis

    • It serves to eliminate cells that are no longer needed, maintaining a constant number of cell populations in tissue.
    • Examples: Removal of excess cells during development, Involution of hormone-dependent tissues on hormone withdrawal, Homeostatic mechanism maintaining cell populations.

    Pathological Apoptosis

    • It eliminates cells injured beyond repair, preventing collateral tissue damage.
    • Examples: DNA damage, Accumulation of misfolded proteins, Certain infections, particularly viral infections, Pathologic atrophy in parenchymal organs after duct obstruction.

    Morphological Features of Apoptosis

    • Involves single cells or small clusters of cells.
    • Cell shrinkage.
    • Membrane blebbing.
    • Chromatin condensation.
    • Nucleus condenses and fragments in an organized manner.
    • Formation of apoptotic bodies.
    • Phagocytosis of apoptotic bodies, usually by macrophages.
    • No inflammatory cells.

    Apoptosis Pathways

    • Pro-apoptotic: Cytochrome c
    • Anti-apoptotic: Bcl-2
    • Activation of caspases brings about apoptosis.
    • Caspases activate proteases and endonucleases that breakdown the DNA.
    • Caspase-3 is an important final enzyme.

    Differences and Features of Necrosis and Apoptosis

    Feature Necrosis Apoptosis
    Induction Pathological conditions Pathological or Physiological conditions
    Number of cells Group of cells Single Cells
    Plasma Membrane Loss of membrane integrity Membrane remains intact
    Cell Size Enlarged (swelling) & lysis Reduced (shrinkage)
    Nucleus Pyknosis → karyorrhexis → karyolysis Fragmentation → formation of apoptotic bodies
    Inflammation Inflammatory response NO inflammatory response
    Fate of Cells Phagocytosed by neutrophils and macrophages Phagocytosed by neighbouring cells
    Biochemical Mechanism Energy-independent Energy-dependent

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    Lecture 4 Cell Death: Necrosis & Apoptosis PDF

    Description

    Explore the crucial processes of necrosis and apoptosis in cellular biology. Understand the different types of necrosis, including coagulative and liquefactive types, and their pathological implications. This quiz is essential for those studying cell biology or related medical fields.

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