Cell Injury and Its Causes
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What is the primary effect of hypoxia on cellular respiration?

  • Activation of aerobic respiration
  • Inhibition of oxidative phosphorylation (correct)
  • Increased intracellular potassium
  • Increased production of ATP

    • Reversible injury leads to an increase in intracellular sodium and a decrease in intracellular potassium.

    True

    What happens to ribosomes during reversible injury?

    They detach from the rough endoplasmic reticulum (RER).

    The accumulation of _____ and lactic acid during hypoxia results in reduced intracellular pH.

    <p>inorganic phosphates</p> Signup and view all the answers

    Which of the following enzymes is NOT activated in response to calcium influx during ischemia?

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

    What is the result of prolonged hypoxia on the cytoskeleton?

    <p>It disappears, leading to loss of ultrastructural features.</p> Signup and view all the answers

    Match the injuries to their characteristics:

    <p>Reversible Injury = Acute cellular swelling and metabolic disturbances Irreversible Injury = Severe damage and loss of cellular structures Hypoxia = Decreased ATP and stimulation of anaerobic glycolysis Reperfusion Injury = Release of toxic oxygen radicals</p> Signup and view all the answers

    The accumulation of calcium particles indicates reversible injury.

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

    Which type of cell death is characterized by swelling and breakdown of organelles?

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

    Apoptosis can occur under pathological conditions only.

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

    What is the primary cause of hypoxic cell injury?

    <p>Inadequate oxygenation of the blood</p> Signup and view all the answers

    ________ agents such as trauma, extremes of temperature, and radiation can lead to cell injury.

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

    Match the following causes of cell injury with their descriptions:

    <p>Hypoxia = Inadequate oxygenation of blood Genetic defects = Conditions like Down's syndrome Nutritional imbalances = Vitamin deficiencies and protein-calorie insufficiency Microbiologic agents = Infections from viruses to tapeworms</p> Signup and view all the answers

    Which intracellular system is NOT explicitly mentioned as vulnerable to injury?

    <p>Cellular enzyme activity</p> Signup and view all the answers

    Calcium levels in the cytosol are maintained at high levels to support cellular functions.

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

    Name one effect of aging on cells.

    <p>Increased vulnerability to injury</p> Signup and view all the answers

    Which of the following is NOT a condition in which free radicals are implicated?

    <p>Rheumatoid arthritis</p> Signup and view all the answers

    Free radicals have a stable configuration due to their unpaired electron.

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

    Identify one mechanism by which chemical injury occurs.

    <p>Combining with a critical molecular component or cellular organelle.</p> Signup and view all the answers

    The enzymatic catabolism of oxygenous chemicals can lead to the formation of _____ free radicals.

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

    Match the free radical with its effect on cell components:

    <p>Lipid peroxidation = Plasma membranes Thymine reaction = DNA Protein cross-linking = Proteins Hydroxyl radical = Cellular components</p> Signup and view all the answers

    What is one of the enzymatic processes that generate superoxide radicals?

    <p>Xanthine oxidase activity</p> Signup and view all the answers

    Hydropic changes indicate irreversible cell injury.

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

    Name one reactive species generated through the reduction-oxidation reactions.

    <p>Superoxide radical</p> Signup and view all the answers

    Which of the following conditions is NOT a cause of fatty change (steatosis)?

    <p>Excessive exercise</p> Signup and view all the answers

    What term is used to describe the accumulation of fat within macrophages of subcutaneous connective tissues?

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

    Fatty change is irreversible and often leads to permanent damage to the liver.

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

    An abnormal accumulation of calcium salts in tissues is referred to as __________.

    <p>pathologic calcification</p> Signup and view all the answers

    Match the following types of deposits with their characteristics:

    <p>Fatty Change = Abnormal accumulation of triglycerides Hemosiderin = Iron-derived granular pigment Cholesterol = Lipids in macrophages during atherosclerosis Glycogen = Vacuoles seen in abnormal glucose metabolism</p> Signup and view all the answers

    What is dystrophic calcification associated with?

    <p>Normal serum calcium levels</p> Signup and view all the answers

    Which of the following cells may be stuffed with lipid due to necrotic cell debris?

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

    Excess fatty acid oxidation is a cause of fatty change in tissues.

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

    Metastatic calcification can occur in normal tissues during hypocalcemia.

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

    List one cause of hypercalcemia.

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

    What type of change occurs in the liver during fatty change as seen under a light microscope?

    <p>Small vacuoles displacing the nucleus</p> Signup and view all the answers

    Dystrophic calcification is often found in ____ areas of necrosis.

    <p>advanced atherosclerosis</p> Signup and view all the answers

    Match the following terms to their descriptions:

    <p>Atrophy = Shrinkage in cell size Hypertrophy = Increase in cell size Dystrophic calcification = Deposition in dead tissues Metastatic calcification = Occurs in normal tissues with hypercalcemia</p> Signup and view all the answers

    Which of the following is a characteristic of hypertrophy?

    <p>Increased organ size due to cell enlargement</p> Signup and view all the answers

    Atrophic cells are dead cells.

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

    What is the biochemical change associated with atrophy?

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

    Study Notes

    Cell Injury

    • Cells maintain a narrow range of physiological activities.
    • When adaptation mechanisms are exceeded, cell injury occurs.
    • Two main patterns of cell death:
      • Necrosis: Cell swelling, protein denaturation, and organellar breakdown.
      • Apoptosis: Programmed cell death, occurring under normal or physiological conditions.

    Causes of Cell Injury

    • Hypoxia: Diminishes aerobic respiration, distinct from ischemia (also causes hypoxic cell injury). Occurs with inadequate oxygenation of the blood.
    • Physical agents: Trauma, temperature extremes, radiation, electric shock, atmospheric pressure changes.
    • Chemicals and drugs: Alter membrane permeability, osmotic homeostasis, or enzyme integrity.
    • Microbiologic agents: Viruses, parasites.
    • Immunologic reactions: Immune system attacks can cause cell injury, e.g., anaphylaxis.
    • Genetic defects: E.g., Down's syndrome, sickle cell anemia.
    • Nutritional imbalances: Protein-calorie deficiency, vitamin deficiencies, diets high in animal fat.
    • Aging: Cellular processes gradually decline.

    Mechanisms of Cell Injury

    • Four vulnerable intracellular systems:
      • Cell membrane integrity (ionic and osmotic regulation).
      • Aerobic respiration.
      • Protein synthesis.
      • Genetic apparatus.
    • Cytosolic free calcium is maintained at low levels by ATP-dependent transporters.
    • Ischemia or toxins increase intracellular calcium, activating enzymes:
      • Phospholipases (degrade membranes).
      • Proteases (protein breakdown).
      • ATPases (ATP depletion).
      • Endonucleases (DNA fragmentation).
      • Oxygen free radicals are key mediators of cell death.

    Ischemic and Hypoxic Injury

    • Reversible Injury:

      • Reduced ATP leads to:
        • Influx of calcium.
        • Sodium pump dysfunction.
        • Intracellular sodium accumulation.
        • Potassium loss.
        • Cell swelling.
        • Accumulation of metabolites (inorganic phosphates, lactic acid, purine nucleotides).
        • Increased anaerobic glycolysis, glycogen depletion.
        • Reduced intracellular pH.
        • Reduced protein synthesis.
        • Loss of cytoskeletal features.

    • Irreversible Injury:

      • Severe mitochondrial vacuolization and calcium accumulation.
      • Extensive plasma membrane damage.
      • Lysosomal swelling.
      • Calcium-mediated injury during reperfusion.
      • Loss of proteins from hyperpermeable membranes.
      • Lysosomal enzyme release and intracellular degradation.
      • Formation of myelin figures.

    Mechanisms of Irreversible Injury:

    • Progressive loss of membrane phospholipids.
    • Cytoskeletal abnormalities.
    • Toxic oxygen radicals from reperfusion.
    • Lipid breakdown products.

    Free Radical Mediation of Cell Injury

    • Free radicals are unstable molecules with unpaired electrons.

    • Generated by:

      • Absorption of radiant energy.
      • Redox reactions.
      • Enzymatic catabolism of chemicals.

    • React with:

      • Plasma membranes (lipid peroxidation).
      • DNA.
      • Proteins.

    Chemical Injury

    • Two Mechanisms:

      • Direct combination with a critical molecule or organelle.
      • Conversion to toxic metabolites (often by P-450 oxidases in the SER).

    • Example: Carbon tetrachloride (CCl4) is converted to CCl3. in the liver, resulting in membrane peroxidation, ER damage, and fatty liver change.

    Patterns of Acute Cell Injury

    • Reversible Cell Injury: Light microscopic changes:

      • Cell swelling.
      • Abnormal exogenous substance deposits.

    • Fatty Change (Steatosis):

      • Accumulation of triglycerides in parenchymal cells.
      • Occurs in the liver, heart, muscle, kidney.
      • Causes: toxins, diabetes, malnutrition, obesity, anoxia.
      • Excess triglycerides may result from defects in fatty acid entry or lipoprotein synthesis.

    Cholesterol and Cholesterol Esters

    • Macrophages in contact with lipid debris become filled with lipid, forming "foamy cells."
    • Atherosclerosis: Smooth muscle cells and macrophages are filled with cholesterol and cholesterol esters.
    • Xanthomas: Accumulations of fat within macrophages in subcutaneous tissues, appearing as nodules.

    Proteins

    • Less common accumulation, e.g., in glomerular diseases with proteinuria.

    Glycogen

    • Accumulation in cases of glucose or glycogen metabolism disorders, appearing as vacuoles.

    Pigments

    • Colored substances, exogenous or endogenous.
      • Melanin: Accumulates in basal cells of the epidermis or dermal macrophages.
      • Hemosiderin: A hemoglobin-derived pigment, golden-brown, accumulates with iron excess.

    Pathologic Calcification

    • Abnormal calcium salt accumulation.
    • Dystrophic calcification: Occurs in dead or dying tissues despite normal calcium levels, evident in atheromas, injured arteries, and aging tissue.
    • Metastatic Calcification: Occurs in normal tissues with hypercalcemia. Causes:
      • Endocrine disorders (hyperparathyroidism).
      • Bone catabolism (multiple myeloma, cancer).
      • Vitamin D intoxication, milk alkali syndrome.
      • Sarcoidosis.
      • Renal failure.

    Cellular Adaptations of Growth and Differentiation

    • Physiologic Adaptations: Responses to normal stimuli (hormones, chemicals).
    • Pathologic Adaptations: Allow cells to modulate their environment and avoid injury.

    Atrophy

    • Shrinkage in cell size due to loss of cell substance.
    • Causes:
      • Reduced workload
      • Loss of innervation
      • Diminished blood supply
      • Inadequate nutrition
      • Loss of endocrine stimulation
      • Aging
    • Cells become smaller to survive with reduced resources.
    • Biochemically: Decreased synthesis, increased catabolism.

    Hypertrophy

    • Increase in cell size due to increased synthesis of structural proteins and organelles.
    • Results in an increase in organ size.

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    Cell Injury PDF

    Description

    Explore the concepts of cell injury, including mechanisms of necrosis and apoptosis. Understand the various factors that lead to cell injury, such as hypoxia, physical agents, and immunologic reactions. This quiz will enhance your knowledge of cellular physiology and pathology.

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