Cell Injury Overview and Causes
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Questions and Answers

What is the initial effect of hypoxia on aerobic respiration?

  • Stable intracellular ATP levels
  • Increased intracellular ATP production
  • Increased respiratory rate in mitochondria
  • Decreased intracellular ATP production (correct)

    • What is one of the consequences of ATP depletion in cells during ischemia?

  • Enhanced aerobic glycolysis
  • Activation of ATPases (correct)
  • Increased calcium efflux
  • Reduced extracellular potassium levels

    • What happens to ribosomes in response to hypoxic conditions?

  • Formation of ribosome clusters
  • Increased attachment to RER
  • Detachment from rough endoplasmic reticulum (correct)
  • Increased protein synthesis

    • Which of the following is characterized by irreversible injury to cells?

    <p>Mitochondrial swelling</p> Signup and view all the answers

    What is a result of prolonged hypoxia on cellular structure?

    <p>Loss of ultrastructural features</p> Signup and view all the answers

    What mediates cell death during ischemic conditions?

    <p>Influx of calcium</p> Signup and view all the answers

    What do toxic oxygen radicals released during reperfusion primarily lead to?

    <p>Further cellular injury</p> Signup and view all the answers

    What is a significant indicator of irreversible injury observed under a microscope?

    <p>Formation of myelin figures</p> Signup and view all the answers

    What does cytoplasmic eosinophilia indicate in the context of cellular injury?

    <p>Cytoplasmic acidosis and loss of ribosomes</p> Signup and view all the answers

    Which of the following describes coagulative necrosis?

    <p>Preservation of structural outlines for days</p> Signup and view all the answers

    Which type of necrosis is primarily associated with bacterial infections?

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

    Which change occurs in the nucleus during cell necrosis that indicates DNA digestion?

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

    What is a common characteristic of fatty change in cells?

    <p>Presence of cytoplasmic vacuoles</p> Signup and view all the answers

    Which of the following best defines necrosis?

    <p>A series of changes following cell death from irreversible injury</p> Signup and view all the answers

    In which type of necrosis would you typically find a 'cheesy' gross appearance?

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

    What cellular change is associated with mitochondrial damage in injury?

    <p>Swelling and development of amorphous densities</p> Signup and view all the answers

    What is the primary characteristic of necrosis?

    <p>Cell swelling and organellar breakdown</p> Signup and view all the answers

    Which of the following is NOT a cause of cell injury?

    <p>Nutritional enhancements</p> Signup and view all the answers

    How does hypoxia differ from ischæmia?

    <p>Hypoxia results from inadequate oxygenation of blood.</p> Signup and view all the answers

    Which intracellular system is NOT vulnerable to injury?

    <p>Energy storage processes</p> Signup and view all the answers

    What factor does NOT influence the cellular response to injurious stimuli?

    <p>Rate of external chemical exposure</p> Signup and view all the answers

    Which mechanism is primarily affected by aging in relation to cell injury?

    <p>Calcium homeostasis</p> Signup and view all the answers

    What role does cytosolic free calcium play in cell injury?

    <p>It is held at low levels by ATP-dependent calcium transporters.</p> Signup and view all the answers

    Which of the following best describes apoptosis?

    <p>It occurs under normal physiological conditions.</p> Signup and view all the answers

    What is the primary characteristic of fatty change (steatosis)?

    <p>Abnormal accumulation of triglycerides</p> Signup and view all the answers

    Which organs are most commonly affected by fatty change?

    <p>Liver, heart, kidney, and other organs</p> Signup and view all the answers

    What external factor can inhibit fatty acid oxidation and thus contribute to fatty change?

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

    What are foamy cells indicative of in macrophages?

    <p>Accumulation of cholesterol and cholesterol esters</p> Signup and view all the answers

    What is the appearance of xanthomas characteristic of?

    <p>Fat accumulation in subcutaneous tissues</p> Signup and view all the answers

    What type of pigment results from an excess of iron in tissues?

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

    What is a main cause of pathological calcification?

    <p>Abnormal accumulation of calcium salts</p> Signup and view all the answers

    What might the first signs of fatty change appear as under a light microscope?

    <p>Vacuoles appearing around the nucleus</p> Signup and view all the answers

    Which of the following is a characteristic of apoptosis?

    <p>Does not elicit an inflammatory response</p> Signup and view all the answers

    What initiates the process of apoptosis?

    <p>Injury by free radicals</p> Signup and view all the answers

    What occurs during the process of apoptosis at the cellular level?

    <p>Cells form cytoplasmic buds and fragment</p> Signup and view all the answers

    Which type of cell death is specifically described as programmed?

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

    Which of the following describes fat necrosis?

    <p>Focal areas of fat destruction following pancreatitis</p> Signup and view all the answers

    Intracellular accumulations can occur due to which of the following reasons?

    <p>Genetic enzymatic defects</p> Signup and view all the answers

    How are apoptotic cells characterized when viewed under H&E stained sections?

    <p>As round masses with intensely eosinophilic cytoplasm</p> Signup and view all the answers

    Which of the following is true about intracellular accumulations?

    <p>They may be produced by the affected cell or elsewhere</p> Signup and view all the answers

    Study Notes

    Hypoxia and Aerobic Respiration

    • Initial Effect of Hypoxia: Hypoxia initially reduces ATP production because aerobic respiration is compromised.
    • Consequences of ATP Depletion: ATP depletion triggers a cascade of cellular events during ischemia, including sodium pump failure, which leads to cell swelling.

    Cellular Responses to Hypoxia

    • Ribosomes and Hypoxia: Ribosomes detach from the endoplasmic reticulum during hypoxic conditions, reflecting a decrease in protein synthesis.

    Cellular Injury and Irreversible Damage

    • Irreversible Cell Injury: Irreversible injury is characterized by profound and persistent disturbances in membrane function, leading to cell death.

    Consequences of Prolonged Hypoxia

    • Hypoxia and Cellular Structure: Prolonged hypoxia causes a breakdown of the cell's structural components, resulting in cellular swelling and eventually cell death.

    Mechanisms of Cell Death

    • Mediators of Ischemic Cell Death: During ischemic conditions, cell death is mediated by both necrosis and apoptosis, triggered by ATP depletion and the accumulation of toxic metabolites.

    Reperfusion Injury

    • Toxic Oxygen Radicals: The reintroduction of oxygen after ischemia, known as reperfusion, can lead to the production of toxic oxygen radicals, which can damage cell membranes.

    Microscopic Indicators of Irreversible Injury

    • Microscopic Indicator: Significant indicators of irreversible injury include nuclear changes like pyknosis, karyorrhexis, and karyolysis, indicating DNA fragmentation.

    Cytoplasmic Eosinophilia and Cell Injury

    • Eosinophilia: Eosinophilia in the cytoplasm of a cell is a sign of cell injury, likely due to the breakdown of cytoplasm and the loss of RNA (which normally stains blue with hematoxylin).

    Types of Cell Necrosis

    • Coagulative Necrosis: Coagulative necrosis is characterized by the preservation of the cell's general shape and outline, with the cytoplasm becoming eosinophilic.

    • Liquefactive Necrosis: Liquefactive Necrosis typically occurs in tissues rich in hydrolytic enzymes, resulting in a liquefied appearance with the breakdown of cell components.

    Nuclear Changes in Necrosis

    • DNA Digestion: During cell necrosis, karyolysis (nuclear fading) occurs, indicating DNA digestion.

    Fatty Change (Steatosis)

    • Fatty Change Characteristics: Fatty change, often seen in the liver, is characterized by an accumulation of triglycerides within the cytoplasm.

    Cell Death: Necrosis vs. Apoptosis

    • Necrosis: Necrosis is a form of accidental cell death, typically accompanied by inflammation, caused by severe injury.
    • Caseous Necrosis: Caseous necrosis, often seen in tuberculosis, is a distinct form of coagulative necrosis characterized by a "cheesy" appearance.

    Mitochondrial Damage and Cell Injury

    • Mitochondrial Damage: Damage to mitochondria can disrupt the electron transport chain, leading to reduced ATP production and increased free radicals.

    Key Feature of Necrosis

    • Characteristic of Necrosis: Necrosis is characteristically accompanied by cell swelling, disruption of plasma membrane integrity, and inflammation.

    Causes of Cell Injury

    • Causes of Injury: Cell Injury can be caused by a variety of factors, including ischemia, chemical toxins, viruses, and physical agents.

    Hypoxia vs. Ischemia

    • Hypoxia and Ischemia: Hypoxia is a deficiency in oxygen supply, while ischemia refers to a reduction in blood flow that may result in hypoxia and other cellular disturbances.

    Vulnerability to Injury

    • Intracellular Systems: Cellular systems vulnerable to injury include the cell membrane, mitochondria, and the endoplasmic reticulum.

    Factors Influencing Injury

    • Factors: The cellular response to injury is influenced by the type and severity of the injury, the duration of exposure, and the type of cell involved.

    Aging and Cell Injury

    • Aging and Cell Injury: Aging impairs the DNA repair mechanisms and promotes cellular senescence, contributing to an increased susceptibility to injury over time.

    Role of Calcium in Cell Injury

    • Calcium: Increased cytosolic calcium plays a prominent role in cell injury by activating various enzymes that can damage cell components.

    Apoptosis

    • Apoptosis: Apoptosis is a process of programmed cell death that occurs in both physiological and pathological conditions, characterized by cell shrinkage and fragmentation without inflammation.

    Fatty Change (Steatosis)

    • Fatty Change: Fatty change results in the accumulation of triglycerides, giving the cell a vacuolated appearance.

    Organs Affected by Fatty Change

    • Organs Affected: The liver is particularly susceptible to fatty change, but other organs like the heart and muscle can also be affected.

    External Factors and Fatty Change

    • Inhibition of Fatty Acid Oxidation: External factors like alcohol consumption, diabetes, and malnutrition can inhibit fatty acid oxidation, contributing to fatty change.

    Foamy Cells: A Marker of Lipid Accumulation

    • Foamy Cells: Macrophages loaded with lipids are called foamy cells, indicative of lipid accumulation within the cells.

    Xanthomas and Lipid Accumulation

    • Xanthomas: Xanthomas are yellowish, fatty deposits that accumulate in the skin, typically in individuals with hyperlipidemia (high blood lipid levels).

    Iron Accumulation and Pigmentation

    • Iron Accumulation: Iron accumulation in tissues results in hemosiderin, a brownish-yellow pigment.

    Causes of Pathological Calcification

    • Pathological Calcification: Pathological calcification, the abnormal deposition of calcium salts in tissues, can be caused by various factors, including injury, inflammation, and hypercalcemia.

    Early Signs of Fatty Change

    • Microscopic Appearance: Early signs of fatty change under a light microscope often appear as small, clear vacuoles within the cytoplasm.

    Characteristics of Apoptosis

    • Apoptosis Characteristics: Apoptosis is characterized by cell shrinkage, nuclear fragmentation, and the formation of apoptotic bodies.
    • Initiation of Apoptosis: Apoptosis is initiated by a variety of signaling pathways, including intrinsic and extrinsic pathways.
    • Apoptotic Processes: Apoptosis involves the activation of caspases, which are a family of proteases that cleave specific proteins.

    Programmed Cell Death: Apoptosis

    • Programmed Cell Death: Apoptosis is specifically referred to as programmed cell death because it is a highly regulated process that involves the activation of a specific set of genes.

    Fat Necrosis

    • Fat Necrosis: Fat necrosis is characterized by the enzymatic breakdown of fats, often associated with pancreatitis.

    Intracellular Accumulations

    • Reasons for Accumulation: Intracellular accumulations can occur due to:
      • Excessive Production: Cells can produce excessive amounts of certain substances.
      • Defective Degradation: Cells may be unable to degrade certain substances effectively.
      • Genetic Defects: Genetic defects can result in the accumulation of abnormal substances.
      • Ingestion of Indigestible Substances: Cells can ingest substances they cannot break down.

    Microscopic Appearance of Apoptotic Cells

    • Apoptotic Cells: Apoptotic cells are characterized by shrinkage, nuclear fragmentation, and the formation of apoptotic bodies, often seen as condensed clumps on H&E stained sections.

    Intracellular Accumulations: General Facts

    • Intracellular Accumulation: Intracellular accumulations are a common feature of cell injury and can have various causes, often indicating metabolic disturbances.

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    Cell Injury PDF

    Description

    This quiz explores the concepts of cell injury, including necrosis and apoptosis, along with the various causes that lead to cellular damage. Understand the differences between hypoxia and ischemia, as well as the impact of physical agents, chemicals, microorganisms, and immune reactions on cell health. Test your knowledge on these fundamental biological processes.

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