Reversible vs Irreversible Cell Injury

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Questions and Answers

What distinguishes coagulative necrosis from liquefactive necrosis?

Liquefactive necrosis preserves tissue architecture.

Coagulative necrosis results in a firm tissue structure. (correct)

Liquefactive necrosis is characterized by wedge-shaped infarcts.

Coagulative necrosis leads to complete cell digestion.

What feature characterizes the gross appearance of an infarct in the renal parenchyma?

Tomb-stone appearance of cells

Liquid viscous mass

Wedge-shaped area (correct)

Abscess formation

In which tissue does liquefactive necrosis typically NOT occur?

Myocardium (correct)

Skin

Liver

Brain

What leads to the formation of an abscess in liquefactive necrosis?

Accumulation of dead leukocytes and debris Signup and view all the answers

What occurs during a cerebral infarct that results in liquefactive necrosis?

High lipid content is enzymatically degraded. Signup and view all the answers

What is the primary cause of coagulative necrosis in solid organs?

Hypoxia Signup and view all the answers

Which of the following scenarios would most likely result in liquefactive necrosis?

Focal infection from bacteria causing pus formation Signup and view all the answers

What microscopic finding is characteristic of coagulative necrosis?

Tomb-stone appearance of cells Signup and view all the answers

What primarily indicates irreversible cell injury?

Nuclear condensation Signup and view all the answers

Which of the following correctly describes necrosis?

It involves membrane integrity loss. Signup and view all the answers

What happens during irreversible cell injury?

Mitochondria show structural distortions. Signup and view all the answers

Which type of necrosis preserves the basic outline of necrotic cells for several days?

Coagulative necrosis Signup and view all the answers

In which of the following types of cell death is cell content leakage commonly observed?

Necrosis Signup and view all the answers

What is true regarding apoptosis compared to necrosis?

Apoptosis is a controlled process of cell death. Signup and view all the answers

What does lysosomal rupture during irreversible injury result in?

Enzyme release and auto-digestion Signup and view all the answers

Which type of necrosis is associated with the presence of both wet and dry forms?

Gangrenous necrosis Signup and view all the answers

What characterizes reversible cell injury?

Cellular swelling and fatty changes Signup and view all the answers

Which of the following is NOT a common morphological change associated with reversible cell injury?

Cell membrane rupture Signup and view all the answers

What structural alteration occurs in the plasma membrane during reversible cell injury?

Stretched and bulging, but remains intact Signup and view all the answers

Which of the following statements about necrosis is accurate?

Necrosis can arise from irreversible injury Signup and view all the answers

What is a common finding in the liver, kidney, and heart during reversible cell injury?

Appearance of lipid filled vacuoles Signup and view all the answers

Which type of cell death is characterized by a cellular breakdown associated with necrosis?

Necrosis Signup and view all the answers

Which cellular change is primarily due to ineffective Na+ K+ ATPase activity during reversible injury?

Cellular swelling Signup and view all the answers

What adaptive change is characterized by an increase in cell size?

Hypertrophy Signup and view all the answers

Study Notes

Reversible Cell Injury

Cell injury is reversible when the cause of injury is removed.
Two main morphologic correlates of reversible cell injury:
- Cellular swelling: due to loss of Na+ K+ ATPase pump activity, so influx of water
- Fatty changes: persistent and excessive severe cell injury in which the cell cannot restore normal functions
Earliest changes on microscopy:
- Hydropic changes or vacuolar degeneration: pinched off segments of ER appear as small clear vacuoles within cytoplasm
- Fatty changes: appearance of lipid filled vacuoles in cytoplasm, commonly seen in kidney, liver and heart
Ultrastructural changes in reversible injury:
- Plasma membrane alteration: stretched, bulges, bleb formation but membrane remains intact
- Mitochondrial changes: water accumulation leads to swelling
- ER: detachment of polysomes & dilatation

Irreversible Cell Injury

Irreversible cell injury: cell membrane rupture, mitochondria shows structural distortion, focal deposits of Ca+2 and loss of ribosomes, lysosome rupture releases enzymes & auto-digestion, nuclear changes i.e. condensation is the most important indicator of irreversible injury
Irreversible injury means cell death
- Two major types:
  - Apoptosis: controlled cell death
  - Necrosis: uncontrolled cell death

Cell Death: Necrosis

Necrosis is a type of cell death associated with loss of membrane integrity and leakage of cellular contents resulting from degradative action of enzymes.
Always pathological!
Cell membrane rupture, so cell contents are leaked out and inflammatory response is seen in surrounding tissue.
Cell digestion is a result of enzymes from dying cells lysosomes and lysosomes of inflammatory leucocytes

Nuclear Changes of Cell Death

Important indicator of irreversible injury
Condensation is the most important indicator of irreversible injury

Necrosis: Types and Morphology

Main morphological types of Necrosis:
- Coagulative necrosis: preservation of the basic outline of the necrotic cells for several days, cell components are dead but basic tissue architecture is preserved and firm
- Liquefactive necrosis: complete cell digestion and transformation of the tissue into a liquid viscous mass, ischemic Cerebral infarcts (brain/stroke), Infective foci (bacteria or fungi) cause abscess or pus formation (accumulation of phagocytes and enzymes of leukocytes that digest tissue)

Coagulative Necrosis

Coagulative Necrosis:
- Denaturation of structural and enzymatic proteins: so proteolysis of the cells are blocked
- Ischemia leads to coagulative necrosis: everywhere except in brain where its Liquefactive necrosis
- Infarct: areas of ischemic necrosis in all solid organs
- Wedge-shaped infarct in the renal parenchyma: Acidosis develops and denatures the enzymatic and structural proteins of the cell giving gross appearance of infarcted “wedge shaped area” and “tomb-stone appearance of cells”
- Coagulative necrosis in myocardial infarction: characterized by "tomb-stone appearance of cells"

Liquefactive Necrosis

Liquefactive necrosis: necrosis with complete cell digestion and transformation of the tissue into a liquid viscous mass
- Ischemic Cerebral infarcts (brain/stroke): high lipid content is enzymatically degraded
- Infective foci (bacteria or fungi): cause abscess or pus formation (accumulation of phagocytes and enzymes of leukocytes that digest tissue)
Pathogenesis and features:
- In cerebral infarct: blood supply to parts of the brain is completely shut-off leading to necrosis, loss of tissue architecture (cell features not identified)
- In abscess: Debris and dead WBCs are accumulated in a walled-off space
Necrosis characterized by liquefactive process resulting in complete digestion of the dead cells:
- Infarct/Hypoxia in brain leads to liquefactive necrosis
- Focal bacterial and fungal infections in other tissues leading to abscess formation.

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Description

This quiz explores the concepts of reversible and irreversible cell injury, including the cellular and ultrastructural changes involved. Test your knowledge on the morphologic correlates and early microscopy changes associated with cell injury. Understand the key differences and implications for cellular function.