Physiological Adaptations and Cell Injury
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Physiological Adaptations and Cell Injury

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Questions and Answers

Which best describes the ultimate outcome of irreversible cell injury?

  • The cell undergoes apoptosis. (correct)
  • The cell undergoes hypertrophy.
  • The cell maintains normal function.
  • The cell adapts through hyperplasia.

    • What type of adaptation occurs when a cell experiences a decrease in workload?

  • Hypertrophy
  • Atrophy (correct)
  • Hyperplasia
  • Metaplasia

    • What event occurs upon irreversible mitochondrial permeability transition?

  • Fatal damage to the cell (correct)
  • Restoration of calcium homeostasis
  • Increased ATP production
  • Cellular recovery becomes possible

    • Which statement about cell injury is accurate?

    <p>The 'point of no return' signifies a transition from reversible to irreversible injury.</p> Signup and view all the answers

    Which of the following enzymes is NOT activated by increased cytosolic calcium during ischemia?

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

    Which adaptation involves a change in the type of cell present in a tissue?

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

    What is the primary consequence of mitochondrial damage related to Cytochrome C?

    <p>Leakage into the cytosol</p> Signup and view all the answers

    Which of the following statements about organ damage due to cellular adaptations is true?

    <p>Organ damage occurs from excessive adaptations to stimuli.</p> Signup and view all the answers

    Which of the following processes is mainly affected by the action of phospholipases during ischemia?

    <p>Membrane integrity</p> Signup and view all the answers

    Which option describes a reversible stage of mitochondrial permeability transition?

    <p>High-conductance channel formation</p> Signup and view all the answers

    What is a direct consequence of reduced ATP synthesis in cells?

    <p>Accumulation of lactic acid</p> Signup and view all the answers

    What role does calcium play when the calcium pump fails due to ATP depletion?

    <p>Calcium influx has damaging effects on cellular components</p> Signup and view all the answers

    Why does cell swelling occur in response to ATP depletion?

    <p>Decreased activity of the sodium pump leads to sodium accumulation</p> Signup and view all the answers

    What happens to ribosomes and protein synthesis when ATP is depleted?

    <p>Ribosomes detach from the Rough Endoplasmic Reticulum, reducing protein synthesis</p> Signup and view all the answers

    Which pathway primarily generates ATP under aerobic conditions?

    <p>Oxidative phosphorylation of adenosine diphosphate</p> Signup and view all the answers

    What is the main consequence of increased cytosolic calcium levels in relation to mitochondrial health?

    <p>Damage to mitochondria</p> Signup and view all the answers

    How does oxygen deprivation affect cellular functions?

    <p>Causes protein misfolding</p> Signup and view all the answers

    Which process directly results from ribosome detachment from the rough endoplasmic reticulum (RER)?

    <p>Decreased protein synthesis</p> Signup and view all the answers

    Which factor is NOT associated with causing mitochondrial damage?

    <p>Low cytosolic calcium levels</p> Signup and view all the answers

    What is a likely outcome if the Na/K pump activity is reduced in a cell?

    <p>Increased intracellular sodium levels</p> Signup and view all the answers

    What is likely to happen when there is an imbalance between radical-generating and radical-scavenging systems?

    <p>Increased oxidative stress causing cell injury</p> Signup and view all the answers

    Which of the following is NOT a source of free radical generation within cells?

    <p>Hormonal signaling pathways</p> Signup and view all the answers

    What effect does lipid peroxidation primarily have on cells?

    <p>Damage to membranes and organelles</p> Signup and view all the answers

    Which of the following free radicals is produced during normal mitochondrial respiration?

    <p>Superoxide anion radical ($O_2^-$)</p> Signup and view all the answers

    What type of injury is most directly associated with reactive oxygen species?

    <p>Chemical and radiation injury</p> Signup and view all the answers

    What is the earliest change associated with cell injury?

    <p>Loss of cell membrane integrity</p> Signup and view all the answers

    Which of the following phenomena signifies irreversible cell injury?

    <p>Inability to reverse mitochondrial dysfunction</p> Signup and view all the answers

    Which event would suggest that a cell has crossed the threshold into irreversible injury?

    <p>Presence of amorphous densities in mitochondria</p> Signup and view all the answers

    What type of damage is associated with irreversible injury to lysosomes?

    <p>Vacuolization of lysosomes</p> Signup and view all the answers

    Which of the following is NOT a hallmark of irreversible cell injury?

    <p>Reversible ATP generation</p> Signup and view all the answers

    Which of the following enzymes is specifically known for breaking down hydrogen peroxide in cells?

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

    What primary role do antioxidants play in cellular mechanisms?

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

    Which of the following is NOT a mechanism leading to membrane damage in ischemic cells?

    <p>Antioxidant depletion</p> Signup and view all the answers

    Which of the following correctly describes the effect of reactive oxygen species on cellular components?

    <p>They cause lipid damage.</p> Signup and view all the answers

    What cellular consequence can result from defects in membrane permeability?

    <p>Cellular injury and dysfunction</p> Signup and view all the answers

    What is the most common target for toxic injury?

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

    Which of the following substances can produce toxic injury to liver cells?

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

    What mechanism can lead to chemical injury in cells?

    <p>Direct interaction with cellular components</p> Signup and view all the answers

    Which toxic agent is associated with the blockage of mitochondrial function?

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

    Reactive oxygen species (ROS) can be generated from which of the following?

    <p>Metabolism of the chemical itself</p> Signup and view all the answers

    What is a primary characteristic of necrotic cells regarding their cytoplasmic appearance?

    <p>Vacuolation resulting in a moth-eaten appearance</p> Signup and view all the answers

    Which type of necrosis is characterized primarily by preserved cell outlines due to protein denaturation?

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

    Which of the following nuclear changes represents fragmentation of the nucleus in necrotic cells?

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

    What type of debris is identified in necrotic cells through electron microscopy?

    <p>Amorphous osmiophilic debris</p> Signup and view all the answers

    What is a defining feature of intracytoplasmic myelin figures in necrotic cells?

    <p>Formation as a result of membrane damage</p> Signup and view all the answers

    What specific type of liver injury is associated with acetaminophen?

    <p>Zonal hepatic necrosis</p> Signup and view all the answers

    Which process is responsible for the degradation of cells during necrosis?

    <p>Enzymatic digestion</p> Signup and view all the answers

    Which chemical is known to have a potential effect of fatty liver and hepatitis?

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

    In the context of necrosis, which of the following statements is true?

    <p>Necrosis can trigger inflammation in surrounding tissues.</p> Signup and view all the answers

    Which enzyme source is NOT involved in the digestion of necrotic cells?

    <p>Lysosomes of survivor cells</p> Signup and view all the answers

    What type of injury is commonly associated with the use of oral contraceptives?

    <p>Hepatic veno-occlusive disease</p> Signup and view all the answers

    Which of the following drugs has unspecified effects listed in the context of chemical injuries?

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

    What mechanism contributes to the formation of toxic metabolites from certain chemicals like acetaminophen?

    <p>Activation by P-450 mixed function oxidases</p> Signup and view all the answers

    Study Notes

    Physiological Adaptations and Cell Injury

    • Steady State: Cells maintain a balance called homeostasis.
    • Adaptations: Cells adjust to persistent stimuli through changes like hypertrophy (growth), hyperplasia (replication), atrophy (shrinkage), and metaplasia (change in cell type).
    • Cell Injury: Occurs when the stimulus exceeds adaptation capacity, causing reversible (non-lethal) or irreversible (lethal) damage.
    • Irreversible Injury (Cell Death): Leads to apoptosis (programmed cell death) or necrosis (uncontrolled cell death).

    Mechanism of Cell Injury

    • ATP Depletion: Decrease in ATP synthesis, crucial for cellular functions, triggers various detrimental effects.
      • Hypoxia: Reduced oxygen supply leads to reduced ATP production and reliance on glycolysis, producing lactic acid and lowering pH.
      • Sodium Pump Failure: Reduced ATP leads to sodium accumulation and potassium loss, causing cell swelling.
      • Calcium Pump Failure: Results in calcium influx, activating enzymes that damage cellular components.
      • Ribosome Detachment: Decreases protein synthesis, leading to irreversible damage.
    • Mitochondrial Damage: Mitochondria are crucial for ATP production and can be damaged by various factors.
      • Increased Cytosolic Calcium: Elevated levels damage mitochondria.
      • Oxidative Stress: Free radicals produced during metabolism damage mitochondria.
      • Phospholipid Breakdown: Directly damages mitochondrial structure.
      • Lipid Breakdown Products: Damaged lipids contribute to mitochondrial damage.
    • Influx of Calcium & Calcium Homeostasis Loss: Ischemia causes calcium influx, activating enzymes that damage cells.
      • ATPases: Hasten ATP depletion.
      • Phospholipases: Cause membrane damage.
      • Proteases: Break down proteins.
      • Endonucleases: Damage DNA.
    • Free Radicals: Reactive oxygen species (ROS) damage lipids, proteins, and nucleic acids.
      • Cells have defense mechanisms to combat ROS, but an imbalance can lead to oxidative stress and injury.
      • Antioxidants (vitamins E, A, C) and enzymes (catalase, superoxide dismutases) neutralize free radicals.
    • Membrane Permeability: Damage to cell membranes can be caused by ATP depletion, calcium-modulated phospholipases, bacterial toxins, and viral proteins.
      • Mitochondrial dysfunction, cytoskeletal abnormalities, ROS, and lipid breakdown products contribute to membrane damage.

    Reversible & Irreversible Cell Injury

    • Reversible Injury: Early changes can be reversed if the stimulus is removed (e.g., decreased ATP, membrane damage, decreased protein synthesis).
    • Irreversible Injury: Persistent or excessive injury leads to irreversible changes, characterized by:
      • Severe mitochondrial damage
      • Extensive plasma membrane damage
      • Swelling of lysosomes
      • Amorphous densities in mitochondria

    Chemical Injury

    • Toxic Agents: Numerous chemicals cause reversible or irreversible injury, affecting various organs, particularly the liver.
      • Examples: carbon tetrachloride, trichloroethylene, alcohol, various drugs, and certain foods.
      • Chemicals produce injury through direct interaction with cellular components or by creating toxic metabolites.
      • Toxic metabolites can act as free radicals, disrupt cellular processes, or generate ROS.
    • Examples of Chemical Injury:
      • Acetaminophen (Tylenol): Can cause liver necrosis and potential hepatic failure.
      • Halothane, Isoniazid: Can lead to fatty liver, hepatitis, and cirrhosis.
      • Alcohol: Can cause hepatocellular cholestasis (bile flow disruption) and hepatic adenomas (liver tumors).
      • Oral contraceptives: Can cause hepatic veno-occlusive disease (blockage of blood vessels in the liver).
      • Azathioprine, anti-neoplastic agents: Effects not specified in the text.
      • Antibiotics (amphotericin B, etc.): Effects not specified in the text.
      • Metals (mercury, cadmium, bismuth, etc.): Can cause acute renal failure.
      • Solvents (ethylene glycol, etc.): Effects not specified in the text.
      • Jodinated contrast agents: Effects not specified in the text.
      • Anti-neoplastic agents (cisplatin, etc.): Effects not specified in the text.

    Necrosis

    • Necrosis: Morphological changes that occur after cell death, resulting from enzyme degradation.
      • Occurs in the context of irreversible injury.
      • Triggers inflammation in surrounding tissues.
      • Involves protein denaturation and cell digestion by enzymes from:
        • Autolysis: From lysosomes of the dead cells.
        • Heterolysis: From lysosomes of immune cells.

    Morphology of Necrosis

    • Eosinophilia: Increased eosin staining due to protein denaturation and loss of glycogen.
    • Cytoplasmic Changes: Vacuoles (gaps) appear within the cytoplasm (moth-eaten appearance). Calcification may occur later.
    • Nuclear Changes: DNA breakdown produces three patterns:
      • Karyolysis: Basophilia (dark staining) fades.
      • Pyknosis: Nucleus shrinks and becomes more darkly stained.
      • Karyorrhexis: Nucleus fragments.

    Electron Microscopy Findings

    • Plasma Membrane Discontinuities: Breaks in the cell membrane.
    • Mitochondrial Dilation/Amorphous Densities: Mitochondria become enlarged and contain dense structures.
    • Intracytoplasmic Myelin Figures: Characteristic features of necrotic cytoplasm.
    • Amorphous Osmiophilic Debris: Darkly stained debris.

    Types of Necrosis

    • Coagulative Necrosis: Protein denaturation is predominant, retaining the cell outline for a period of time.
    • Liquefactive Necrosis: Characteristic of bacterial or fungal infections, where cells are digested and liquefied.
    • Caseous Necrosis: Associated with tuberculosis, where dead cells appear as a cheesy, crumbly substance.
    • Fat Necrosis: Areas of fat destruction, often caused by pancreatitis, where fat cells release fatty acids which interact with calcium to produce chalky white deposits.

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    Description

    Explore the intricate mechanisms of cellular adaptations and the impacts of cell injury. This quiz covers concepts such as homeostasis, various forms of cell injury, and the physiological responses to stressors. Understand the balance between adaptation and injury and the cellular processes that lead to apoptosis and necrosis.

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