Questions and Answers
Programmed cell death occurs only when cells are damaged.
False
Apoptosis is a type of cell death that results in inflammation.
False
Cells that undergo apoptosis are replaced by mature cells during development.
True
Apoptosis only occurs in cells that are damaged beyond repair.
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Apoptosis is a natural response to the presence of foreign agents in the body.
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Apoptosis can occur in cells of the immune system.
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Liquefactive necrosis is a type of programmed cell death.
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Apoptosis is an essential process for maintaining tissue homeostasis.
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Caseous necrosis is characterized by the presence of yellow-black debris.
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DNA damage activates proapoptotic proteins.
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Viral proteins can directly activate caspases.
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Cytotoxic T lymphocytes can kill infected cells by activating caspases.
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Lymphocytes play a role in caseous necrosis.
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Mitochondrial pathways are involved in apoptosis.
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Proapoptotic proteins can inhibit apoptosis.
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Aspartic acid residues are involved in caseous necrosis.
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Coagulative necrosis is characterized by the loss of nuclei and preservation of cell outlines.
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Apoptosis is a type of necrosis that occurs in response to tissue damage.
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In apoptotic cells, the nucleus and cytoplasm are destroyed by enzymes activated by specific signals.
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Apoptosis serves to eliminate damaged cells and maintain tissue homeostasis.
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Coagulative necrosis is a type of apoptosis.
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Phagocytes play a role in the clearance of apoptotic cells.
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Apoptosis occurs only in response to genetic mutations.
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Coagulative necrosis is commonly seen in kidney infarcts.
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Fragments resulting from cell death are engulfed by neighboring cells.
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Severe DNA damage always leads to apoptosis.
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Accumulation of misfolded proteins gives rise to ER stress.
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Apoptotic bodies are engulfed by immune cells.
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Certain viruses can trigger apoptosis in infected cells.
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Apoptosis always results in inflammation.
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BAX and BAK are pro-apoptotic molecules.
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Apoptosis is a passive process that occurs in response to cellular damage.
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Necrosis is a physiologic process that eliminates unwanted cells.
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Apoptosis is characterized by a disrupted plasma membrane.
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Cell size is reduced in necrosis.
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In apoptosis, the nucleus undergoes pyknosis.
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Necrosis and apoptosis are both regulated by molecular pathways.
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Apoptotic cells are always inflammatory.
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In apoptosis, cellular contents are released into apoptotic bodies.
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Necrosis is a means of eliminating unwanted cells.
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The plasma membrane is intact in necrotic cells.
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Apoptosis is a rapid process that occurs within minutes.
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Study Notes
Cell Injury and Cell Death
- Cell injury can lead to two types of cell death: necrosis and apoptosis
- Necrosis:
- Cell size: enlarged (swelling)
- Nucleus: pyknosis → karyorrhexis → karyolysis
- Plasma membrane: disrupted
- Cellular contents: enzymatic digestion; may leak out of cell
- Adjacent inflammation: frequent
- Physiologic or pathologic role: invariably pathologic (culmination of irreversible cell injury)
- Apoptosis:
- Cell size: reduced (shrinkage)
- Nucleus: fragmentation into nucleosome-sized fragments
- Plasma membrane: intact; altered structure, especially orientation of lipids
- Cellular contents: intact; may be released in apoptotic bodies
- Adjacent inflammation: no
- Physiologic or pathologic role: often physiologic means of eliminating unwanted cells; may be pathologic after some forms of cell injury
Features of Necrosis and Apoptosis
- Table 1.1: comparison of necrosis and apoptosis features
Pathways of Cell Death
- Apoptosis:
- Physiologic apoptosis:
- Occurs during development of organisms
- Eliminates unwanted or damaged cells
- Pathologic apoptosis:
- Occurs in response to cell damage, especially DNA damage
- Can be triggered by various stimuli, including infections and certain chemicals
- Physiologic apoptosis:
- Necrosis:
- Occurs in response to severe cell injury, especially DNA damage
- Can be triggered by various stimuli, including infections and certain chemicals
Types of Apoptosis
- Physiologic apoptosis:
- Developmental apoptosis: occurs during development of organisms
- Immune response apoptosis: occurs in response to infections and other immune stimuli
- Tissue homeostasis apoptosis: occurs to maintain tissue balance and eliminate unwanted cells
- Pathologic apoptosis:
- DNA damage apoptosis: occurs in response to DNA damage
- Infection apoptosis: occurs in response to infections
- Chemical apoptosis: occurs in response to certain chemicals
Morphology of Cell Death
- Necrosis:
- Coagulative necrosis: characterized by preservation of cell outlines, with loss of nuclei and inflammatory infiltrate
- Liquefactive necrosis: characterized by dissolution of tissue
- Caseous necrosis: characterized by formation of cheesy debris
- Apoptosis:
- Morphologic changes: cell shrinkage, chromatin condensation, and nuclear fragmentation
- Formation of apoptotic bodies: intact cellular contents are released in apoptotic bodies, which are then phagocytosed by other cells
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Description
This quiz covers the concepts of cell injury, mitochondria function, and restoration processes. It tests your understanding of cellular responses to damage and regulation mechanisms.
