Pathology Chapter: Necrosis and Apoptosis

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Questions and Answers

What is the primary microscopic appearance of necrosis caused by loss of glycogen particles?

Glassy homogeneous appearance (correct)

Hazy cloudiness

Grainy texture

Pearly luster

Which type of necrosis involves the formation of a fibrous capsule surrounding solid debris?

Caseative necrosis

Liquefactive necrosis

Fibrinoid necrosis

Coagulative necrosis (correct)

Which type of necrosis is primarily characterized by the death of individual cells rather than groups?

Liquefactive necrosis

Apoptosis (correct)

Fibrinoid necrosis

Caseative necrosis

What type of material is typically drained by lymphatics in necrosis?

Fluid Signup and view all the answers

What is a common result of large area necrosis?

Dystrophic calcification Signup and view all the answers

What is a key characteristic of apoptosis at the microscopic level?

Formation of surface cytoplasmic blebs Signup and view all the answers

Which of the following can trigger apoptosis as a pathological cause?

Infections such as viral hepatitis Signup and view all the answers

What process commonly follows the death of apoptotic cells?

Phagocytosis by macrophages Signup and view all the answers

Apoptotic cells exhibit which of the following changes?

Smaller cell size with denser cytoplasm Signup and view all the answers

What is NOT a cause of apoptosis?

Cellular response to mechanical injury Signup and view all the answers

What is a primary cause of ATP depletion in cells?

Hypoxia Signup and view all the answers

Which of the following is characteristic of reversible cell injury?

Cloudy swelling Signup and view all the answers

In what way does the duration of cell injury affect its outcome?

Long duration may result in irreversible injury Signup and view all the answers

Which type of injury is characterized by the accumulation of water in cells?

Hydropic swelling Signup and view all the answers

What is one of the main effects of increased intracellular calcium due to cell injury?

Activation of multiple intracellular enzymes Signup and view all the answers

Which of the following types of cell injury is not reversible?

Necrosis Signup and view all the answers

What is a common cause of chemical cell injury?

Toxic substances Signup and view all the answers

What is the effect of severe cell injury on active parenchymatous cells compared to supporting stroma?

Active parenchymatous cells suffer more Signup and view all the answers

Which condition is characterized by the accumulation of lactic acid and increased intracellular osmotic load?

Cloudy swelling Signup and view all the answers

Which organs are most affected by cloudy swelling?

Liver, kidney, and heart Signup and view all the answers

What is a key morphological characteristic of hydropic swelling?

Swelling and vacuoles in the cytoplasm Signup and view all the answers

What typically happens to a cell if injury continues beyond the initial reversible phase?

Proceeds to irreversible injury Signup and view all the answers

Which type of swelling is characterized by pathological accumulation of excess fat in cells?

Fatty change Signup and view all the answers

What outcome is expected if the injury to a cell stops during cloudy swelling?

Cell returns to normal Signup and view all the answers

Which of the following is an example of hydropic swelling?

Liver damage from viral hepatitis Signup and view all the answers

Which factor contributes to the pathogenesis of both cloudy and hydropic swelling?

Lactic acid accumulation Signup and view all the answers

What is the primary reason for fat accumulation in cells during fatty change?

Diminished enzyme activity Signup and view all the answers

Which condition is an example of patchy fatty change?

Chronic venous congestion Signup and view all the answers

In which phase does a cell return to normal after an injury?

Reversible injury Signup and view all the answers

What histological change is characterized by nuclear shrinkage and increased basophilia?

Pyknosis Signup and view all the answers

What is the defining feature of necrosis?

Local death of a large group of cells Signup and view all the answers

Which of the following is associated with karyorrhexis?

Nuclear fragmentation Signup and view all the answers

What would indicate the presence of inflammatory hyperemia in necrosis?

Surrounded by a red area Signup and view all the answers

What does cytoplasmic eosinophilia indicate in necrotic cells?

Cell swelling and damage Signup and view all the answers

Study Notes

Cell Response to Injury

Learning outcomes include: enumerating causes and types of cell response to injury; describing different mechanisms of cell injury; comparing reversible and irreversible cell injury; defining different types of cell injury; describing gross and microscopic pictures of injury types; describing the pathogenesis and fate of reversible cell injury; comparing necrosis and apoptosis; and comparing different types of necrosis.

Causes of Cell Injury

Causes include physical factors, infection, hypoxia, chemicals, and immunological factors.

Mechanisms of Cell Injury

Mechanisms of cell injury include ATP depletion, membrane damage, increases in intracellular calcium, and formation of oxygen-derived free radicals. A injurious stimulus initiates these events.

Mechanisms of Cell Injury - Hypoxia

Hypoxia is a key cause of cell injuries, often due to ischemia.
The processes involved include: loss of energy-dependent cellular function; oxidative phosphorylation decreases and thus ATP; Na pump dysfunction; influx of Ca++, H₂O, and Na+; loss of K+; ER and cellular swelling; loss of microvilli and blebs; anaerobic glycolysis; glycogen clumping; nuclear chromatin clumping; protein synthesis decreases; lipid deposition; and general detachment of ribosomes.

Mechanisms of Cell Injury - Other factors

Other mechanisms include membrane damage; enzymatic digestion of cellular components, leading to cell death; comparing pro-apoptotic vs. anti-apoptotic proteins and their effect on survival signals; and intracellular Ca2+ increase leading to activation of multiple intracellular enzymes (e.g., ATPase, phospholipase, protease, endonuclease), which can disrupt membranes and cytoskeletal proteins, leading to nuclear damage.
- Formation of reactive oxygen species (ROS), such as superoxide (O2-) and hydrogen peroxide (H2O2), is another factor.

Effect of Cell Injury

The effect of cell injury is dependent on the nature, duration, severity, and type of cell affected.

Reversible vs. Irreversible Cell Injury

Reversible injury is mild and short in duration, while irreversible injury is severe and long in duration.
Active parenchymal cells, with a higher metabolic rate, are more affected than supporting stroma cells during injury.

Types of Reversible Cell Injury

Types of reversible cell injury include cloudy swelling, hydropic swelling, and fatty change.

Cloudy Swelling

Definition: A reversible cell injury characterized by cell swelling due to water accumulation and cytoplasmic granularity.
Causes: Physical factors, infection, hypoxia, or chemical/immunological factors.
Pathogenesis: Ischemia hinders oxidative phosphorylation; anaerobic glycolysis increases; lactic acid accumulation increases pH; and osmotic load increases. Na/K pump failure disrupts cellular water balance.
Gross and microscopic findings: Clinical changes include no significant change; proteinuria and dilation and decreased contractility; in section, there are enlarged, swollen cells with a cloudy, granular appearance.
Fate: If the injury stops, the cell returns to normal; if injury continues, proceeds to hydropic swelling.

Hydropic Swelling

Definition: A reversible cell injury involving morphological swelling and vacuoles in cell cytoplasm due to excess water accumulation.
Causes and pathogenesis are similar to cloudy swelling.
Gross and microscopic findings: Affected cells are swollen, with vacuoles appearing in the cytoplasm.
Fate: If injury stops, cell returns to normal; if injury continues, leads to irreversible damage.

Fatty Change

Definition: Reversible cell injury involving pathological fat accumulation in cells.
Causes: Excess fat intake and viral hepatitis, among other causes detailed below
Pathogenesis: Fat produced or carried to injured cells cannot be metabolized due to limited enzyme activity which accumulates in the cytoplasm, leading to the appearance of vacuoles.
Gross and microscopic findings: Patchy or diffuse fat accumulation is observed, sometimes resembling a "nutmeg liver" appearance.
Fate: If injury stops, cell returns to normal; if injury continues leads to irreversible injury.

Necrosis

Definition: Local death of a large group of cells or tissues within a living body due to direct or consequential injury from reversible injury.
Causes: Physical, infection, hypoxia, or chemical/immunological factors.
Gross findings: Surrounded by a red area due to inflammatory hyperemia.
Microscopic findings:
- Nuclear: Pyknosis (nuclear shrinkage), karyorrhexis (nuclear fragmentation), and karyolysis (nuclear dissolution);
- Cytoplasmic: Cytomegaly (cell swelling), indistinct cell membrane, Ca2+ deposition, cytoplasmic eosinophilia in H&E (due to loss of cytoplasmic RNA and denatured cytoplasmic proteins), and a glassy homogenous appearance (loss of glycogen particles).
Types include: coagulative, liquefactive, caseative, fat, and fibrinoid.
Fate: Small areas heal by macrophage engulfment of solid debris, fluid drainage, and tissue regeneration. Large areas result in a fibrous capsule and dystrophic calcification.

Apoptosis

Definition: Energy-dependent, programmed cell death essential for eliminating unwanted cells, critical for normal development.
Causes: Normal cell turnover, embryogenesis, hormone-dependent involution, cellular damage.
Pathologic examples include, DNA damage, infections (viral hepatitis).
Gross findings: Microscopic.
Microscopic findings: Cell shrinkage, dense cytoplasm, tightly packed organelles, chromatin condensation, surface blebbing, formation of membrane-bound apoptotic bodies.
Fate: Phagocytosis of apoptotic bodies by macrophages and degradation of cell contents by lysosomal enzymes.

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Description

This quiz explores key concepts in pathology, particularly focusing on necrosis and apoptosis. Test your knowledge on the various types of necrosis, their microscopic characteristics, and the processes associated with cell death. Understand the differences between necrosis and apoptosis, along with their underlying mechanisms.