Cell Injury and Death Concepts

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Questions and Answers

What characterizes necrosis in cell injury?

Cell shrinkage and chromatin condensation

Cell swelling and organellar breakdown (correct)

Programmed cessation of metabolic activity

Disintegration of cellular components without inflammation

Which type of injury directly results from inadequate oxygenation of the blood?

Nutritional deficiencies

Microbial infection

Physical trauma

Hypoxia (correct)

What is a common consequence of cellular injury related to membrane integrity?

Altered membrane permeability (correct)

Increased protein synthesis

Enhanced aerobic respiration

Improved cellular adaptability

Which factor does NOT contribute to the severity of cell injury?

Presence of extracellular nutrients Signup and view all the answers

What system is NOT among the four vulnerable intracellular systems to injury?

Hormonal regulation Signup and view all the answers

A dietary habit rich in which component has been implicated in atherosclerosis pathogenesis?

Animal fat Signup and view all the answers

Apoptosis is best described as:

A regulated form of cell death under physiological conditions Signup and view all the answers

What type of agents can cause cell injury by changing osmotic homeostasis?

Chemicals and drugs Signup and view all the answers

What distinguishes dystrophic calcification from metastatic calcification?

Dystrophic calcification occurs despite normal serum levels of calcium. Signup and view all the answers

Which of the following is NOT a cause of hypercalcæmia?

Aging Signup and view all the answers

Which physiological adaptation is characterized by a shrinkage in cell size due to loss of cell substance?

Atrophy Signup and view all the answers

Which of the following conditions is related to pathological adaptations in cells?

Adaptations permitting escape from injury Signup and view all the answers

What is the primary difference between atrophy and apoptosis?

Atrophy is reversible, while apoptosis is irreversible. Signup and view all the answers

Which type of necrosis is characterized by the preservation of structural outlines of the coagulated tissue for an extended period?

Coagulative necrosis Signup and view all the answers

What is the morphologic appearance of necrosis primarily the result of?

Enzymatic digestion and protein denaturation Signup and view all the answers

In which type of necrosis does the affected tissue exhibit a cheesy, white gross appearance?

Caseous necrosis Signup and view all the answers

What is the primary cellular change observed in eosinophilia during cytoplasmic alterations?

Loss of glycogen Signup and view all the answers

What type of necrosis is typically associated with focal bacterial or fungal infections?

Liquefactive necrosis Signup and view all the answers

Which nuclear change is indicative of nuclear shrinkage and increased basophilia primarily seen in apoptosis?

Pyknosis Signup and view all the answers

The term gangrenous necrosis refers to a type of necrosis that involves which processes?

Ischemic coagulative necrosis with superimposed infection Signup and view all the answers

What type of changes in the endoplasmic reticulum are observed during necrosis?

Dilatation and detachment of ribosomes Signup and view all the answers

Eosinophilia indicates which specific change in the cytoplasm during cell injury?

Cytoplasmic acidosis Signup and view all the answers

Which of the following is NOT a mechanism by which free radicals can cause cell injury?

Promotion of oxidative phosphorylation Signup and view all the answers

Which of the following are primary characteristics of necrosis observed in living tissue?

Cell death leading to irreversible damage Signup and view all the answers

What role does copper and iron play in free radical formation?

They accept or donate electrons Signup and view all the answers

During which physiological process are small amounts of toxic intermediate species generated?

Reduction-oxidation (redox) reactions Signup and view all the answers

What type of changes are only seen in the light microscope during reversible cell injury?

Cell swelling with clear vacuoles Signup and view all the answers

Which chemical is converted into a toxic free radical during the metabolism in the liver?

Carbon tetrachloride Signup and view all the answers

What is a consequence of lipid peroxidation in cells?

Membrane integrity loss Signup and view all the answers

What happens within 2 hours of carbon tetrachloride exposure to the liver?

Development of fatty liver changes Signup and view all the answers

Which of the following components do free radicals primarily react with?

Cellular organelles Signup and view all the answers

What is a primary function of xanthine oxidase in the context of free radicals?

Production of superoxide radicals Signup and view all the answers

Which of the following best describes the enzymatic action of P-450 oxidases in the context of chemical injury?

They convert non-toxic chemicals into toxic metabolites. Signup and view all the answers

What is a primary cause of fatty change in parenchymal cells?

Toxin exposure Signup and view all the answers

In which organ is fatty change most commonly observed?

Liver Signup and view all the answers

What is the appearance of fatty change under the light microscope?

Clear spaces displacing the nucleus Signup and view all the answers

What condition is associated with the accumulation of cholesterol in macrophages?

Atherosclerosis Signup and view all the answers

Which of the following correctly describes xanthomas?

Lipids accumulating in dermal macrophages Signup and view all the answers

What role does anoxia play in fatty change?

It inhibits fatty acid oxidation Signup and view all the answers

What pigment accumulates in tissues as a result of iron excess?

Hemosiderin Signup and view all the answers

What characterizes pathological calcification?

Abnormal accumulation of calcium salts Signup and view all the answers

What metabolic condition is associated with glycogen accumulation in vacuoles?

Abnormal metabolism of glucose Signup and view all the answers

Which of the following does NOT commonly cause fatty change?

Iron overload Signup and view all the answers

Study Notes

Cell Injury

Cells strive to maintain a stable internal environment.
When cells encounter stress, they adapt to preserve their viability.
If adaptive mechanisms are overwhelmed, cell injury ensues.

Patterns of Cell Death

Necrosis is cell death caused by noxious stimuli, characterized by cell swelling, protein denaturation, and organelle breakdown.
Apoptosis is a programmed cell death occurring in normal or physiologic conditions.

Causes of Cell Injury

Hypoxia: Inadequate oxygenation of the blood, impacting aerobic oxidative respiration.
Physical Agents: Trauma, extremes of temperature, radiation, electric shock, sudden changes in atmospheric pressure.
Chemicals and Drugs: Can alter membrane permeability, osmotic homeostasis, and enzyme cofactor integrity.
Microbiologic Agents: Viruses and parasites.
Immunologic Reactions: Immune system can cause injury, e.g., anaphylactic reaction.
Genetic Defects: E.g., Down's syndrome, sickle cell anemia.
Nutritional Imbalances: Protein-calorie insufficiency, vitamin deficiencies. Diets rich in animal fat contribute to atherosclerosis.
Aging:

Mechanisms of Cell Injury

Cell response depends on the type of injury, its duration, severity, and cell type.
Four main cellular components are vulnerable to injury:
- Cell membrane integrity
- Aerobic respiration
- Protein synthesis
- Genetic apparatus
Intracellular calcium levels are critical for cell function.

Free Radical Mediation of Cell Injury

Free radicals are unstable chemical species that can damage cells.
Implicated in: Chemical injury, radiation damage, oxygen toxicity, cellular aging, microbial killing, inflammatory damage, tumor killing.
Generated within cells by:
- Absorption of radiant energy (e.g., water hydrolysis to OH• and H•)
- Redox reactions, including the production of superoxide radicals (O2•-), hydrogen peroxide (H2O2), and hydroxyl radicals (OH•).
- Enzymatic catabolism of oxygenous chemicals (e.g., CCl4 conversion to CCl3• in the liver).
Free radicals react with:
- Lipid peroxidation of plasma membranes
- DNA (e.g., reacting with thymine)
- Cross-linking of proteins

Chemical Injury

Two main mechanisms:
- Direct combination with cellular components (e.g., mercury binds to sulfhydryl groups).
- Conversion to reactive toxic metabolites via P-450 oxidases (e.g., CCl4 converted to CCl3•).
CCl4 injury results in rapid breakdown of endoplasmic reticulum, swelling, and reduced lipid export, leading to fatty liver changes.

Patterns of Acute Cell Injury

Reversible Cell Injury

Light microscopic changes:
- Cell swelling (hydropic changes or vacuolar degeneration)
- Cytoplasmic eosinophilia
- Fatty change
Ultrastructural changes:
- Plasma membrane blebbing and distortion
- Mitochondrial swelling and phospholipid densities
- Endoplasmic reticulum dilatation and ribosome detachment
- Nuclear alterations (e.g., disaggregation of granular elements)

Necrosis

Morphological changes resulting from enzymatic digestion and protein denaturation.
Examples:
- Cytoplasmic eosinophilia
- Nuclear changes: Karyolysis (DNA digestion), Pyknosis (nuclear shrinkage), Karyorrhexis (nuclear fragmentation)

Types of Necrosis

Coagulative Necrosis: Preservation of cell outlines, characteristic of hypoxic death in most tissues (except brain).
Liquefactive Necrosis: Characterized by liquefaction, caused by bacterial/fungal infections or hypoxic death in the CNS.
Gangrenous Necrosis: Ischemic coagulative necrosis with superimposed infection.
Caseous Necrosis: Cheesy appearance, seen in tuberculosis infections.

Abnormal Exogenous Substances

Accumulate when cells lack the machinery to metabolize or transport them.

Fatty Change (Steatosis)

Abnormal triglyceride accumulation within parenchymal cells.
Most commonly seen in the liver, reversible.
Causes: Toxins, diabetes, protein malnutrition, obesity, anoxia.
Severity of fatty change affects cellular function.

Cholesterol and Cholesterol Esters

Accumulate in macrophages and other cells, becoming foamy cells.
Seen in atherosclerosis (smooth muscle cells and macrophages), xanthomas (subcutaneous connective tissues).

Proteins

Less commonly accumulated, e.g., in glomerular diseases with proteinuria.

Glycogen

Accumulation seen in abnormal glucose or glycogen metabolism.

Pigments

Colored substances, exogenous or endogenous.
Melanin: Accumulates in basal epidermal cells (e.g., freckles), dermal macrophages.
Hemosiderin: Iron-containing pigment, accumulates with local or systemic iron excess.

Pathologic Calcification

Abnormal accumulation of calcium salts, with smaller amounts of iron, magnesium.
Dystrophic Calcification: Deposition in dead or dying tissues, occurs with normal serum calcium levels.
- Seen in atherosclerosis, aortic valves, necrosis.
- Appears as basophilic deposits, sometimes forming bone.
Metastatic Calcification: Deposition in normal tissues due to hypercalcemia.
- Causes: Hyperparathyroidism, bone catabolism (tumors, leukemia), vitamin D intoxication, renal failure.
- May be widespread, affecting interstitial tissues, kidneys, lungs, gastric mucosa.

Cellular Adaptations of Growth and Differentiation

Physiological Adaptations: Responses to normal stimuli, e.g., breast growth and lactation.
Pathological Adaptations: Cellular response to noxious stimuli to escape injury.

Atrophy

Shrinkage in cell size due to loss of cell substance.
May affect entire organs.
Causes: Decreased workload, loss of innervation, diminished blood supply, inadequate nutrition, loss of endocrine stimulation, aging.
Biochemically: Decreased synthesis, increased catabolism.

Hypertrophy

Increase in cell size due to increased protein synthesis and organelle production.
Increases organ size.

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Description

Explore the essential concepts of cell injury and death, focusing on the mechanisms of necrosis and apoptosis. Understand the causes of cell damage including hypoxia, physical agents, and microbiologic factors. This quiz covers the fundamental principles relevant to cell health and pathology.