Cell Injury and Adaptation

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Questions and Answers

What characterizes dystrophic calcification in tissues?

It is predominantly found in healthy tissues with strong blood supply.

It occurs in the presence of elevated serum calcium levels.

It arises in dead or dying tissues despite normal calcium metabolism. (correct)

It is associated with significant functional impairment of affected organs.

Which of the following conditions is NOT a cause of hypercalcemia?

Advanced renal failure.

Milk alkali syndrome.

Primary hyperparathyroidism.

Significant weight loss due to dieting. (correct)

Which statement about hypertrophy is true?

Hypertrophy leads to complete cell death within the tissue.

Hypertrophy involves the shrinkage of cells and organs.

It occurs exclusively in response to hormonal changes.

It results in an increase in cell size due to protein synthesis. (correct)

What is a key characteristic of necrosis compared to apoptosis?

Necrosis is characterized by cell swelling and organellar breakdown. Signup and view all the answers

What best describes atrophy in cells?

It occurs due to loss of cell substance and results in reduced function. Signup and view all the answers

Which of the following contributes to hypoxic cell injury?

Inadequate oxygenation of the blood. Signup and view all the answers

Where does metastatic calcification typically occur?

Primarily in normal tissues without impairment. Signup and view all the answers

Which cellular element is primarily affected by oxidative stress?

Cell membrane integrity. Signup and view all the answers

Which injury factor is least likely to contribute to cell injury?

Enhanced exercise. Signup and view all the answers

In cell injury scenarios, which of the following systems is particularly sensitive to disruption?

Protein synthesis. Signup and view all the answers

What distinguishes ischæmia from hypoxia?

Hypoxia can occur due to anemia, while ischæmia cannot. Signup and view all the answers

What role does age play in cellular response to injury?

Aging can weaken cellular mechanisms for coping with injuries. Signup and view all the answers

What is the most significant consequence of impaired aerobic respiration in cells?

Decreased ATP production. Signup and view all the answers

Which of the following are examples of cell injury implicated by free radicals?

Oxygen toxicity Signup and view all the answers

What process primarily generates superoxide radicals inside cells?

Reduction of O2 during redox reactions Signup and view all the answers

Which of the following statements about chemical injury is true?

Mercury binds to sulfhydryl groups in cell membranes. Signup and view all the answers

How do free radicals primarily affect cellular membranes?

By causing lipid peroxidation Signup and view all the answers

What is a common consequence of intracellular free radical formation?

Decreased protein synthesis Signup and view all the answers

What initial cellular process is affected by hypoxia leading to cell injury?

Oxidative phosphorylation Signup and view all the answers

Which enzyme is involved in generating superoxide radicals?

Xanthine oxidase Signup and view all the answers

Which enzyme's activity is stimulated due to decreased ATP and AMP during hypoxic conditions?

Phosphofructokinase Signup and view all the answers

What effect does carbon tetrachloride (CCl4) have on the liver regarding cell injury?

It results in membrane peroxidation within a short time frame. Signup and view all the answers

What cellular change occurs when hypoxia leads to a reduction of the plasma membrane sodium pump?

Increased calcium influx Signup and view all the answers

Which component of the cell is MOST commonly affected by free radical reactions?

Cell membrane phospholipids Signup and view all the answers

Which of the following is NOT associated with irreversible injury in cells?

Detachment of ribosomes Signup and view all the answers

What immediate cellular change is associated with reversible cell injury?

Cell swelling and vacuolar degeneration Signup and view all the answers

What is a mechanism contributing to membrane injury during reperfusion of ischaemic tissues?

Release of toxic oxygen radicals Signup and view all the answers

What role does iron play in free radical formation?

Iron accepts or donates electrons, contributing to radical generation. Signup and view all the answers

Which of the following conditions is most likely to contribute to acute cellular swelling during hypoxia?

Increased intracellular sodium Signup and view all the answers

What structural feature is often lost in cells experiencing prolonged hypoxia?

Cell membrane microvilli Signup and view all the answers

Which process primarily leads to the degradation of cytoplasmic components during irreversible injury?

Activation of lysosomal enzymes Signup and view all the answers

What does the accumulation of lactic acid during hypoxia indicate?

Shift to anaerobic glycolysis Signup and view all the answers

What role does calcium play in the context of cellular injury and death?

Activates various degrading enzymes Signup and view all the answers

What is the primary cause of cytoplasmic eosinophilia?

Cytoplasmic acidosis and loss of ribosomes Signup and view all the answers

Which necrosis type is characterized by the preservation of structural outlines of coagulated cells?

Coagulative necrosis Signup and view all the answers

Which type of necrosis is specifically associated with tuberculous infection?

Caseous necrosis Signup and view all the answers

What alterations are associated with mitochondrial changes in injury?

Swelling and phospholipid-rich densities Signup and view all the answers

What type of necrosis results primarily from hypoxic cell death in the central nervous system?

Liquefactive necrosis Signup and view all the answers

Which of the following processes contributes to the morphologic appearance of necrosis?

Enzymatic digestion and denaturation of proteins Signup and view all the answers

What is karyorrhexis referring to in nuclear changes during necrosis?

Fragmentation of pyknotic nucleus Signup and view all the answers

Which cellular changes are indicative of necrosis?

Cytoplasmic vacuolation and eosinophilia Signup and view all the answers

What is the term for the process of cell digestion derived from dead cells?

Autolysis Signup and view all the answers

Which of the following best describes gangrenous necrosis?

Coagulative necrosis with superimposed infection Signup and view all the answers

Study Notes

Cell Injury

Cells maintain a narrow range of physiological activities, but can adapt to stress
When adaptive capacity is exceeded, cell injury occurs
Two main cell death patterns:
- Necrosis: Occurs due to noxious conditions, characterized by swelling, protein denaturation, and organellar breakdown
- Apoptosis: Programmed cell death occurring in normal or physiologic conditions

Causes of Cell Injury

Hypoxia: Reduced oxygen supply to cells, impacting aerobic respiration (distinct from ischemia, which also causes hypoxic injury)
Physical Agents: Trauma, extreme temperatures, radiation, electric shock, pressure changes
Chemicals and Drugs: Alter membrane permeability, osmotic balance, or enzyme integrity
Microbiologic Agents: Viruses, bacteria, parasites
Immunologic Reactions: Immune system responses can cause cell injury (e.g., anaphylaxis)
Genetic Defects: Inherited genetic disorders (e.g., Down Syndrome, sickle cell anemia)
Nutritional Imbalances: Protein-calorie deficiency, vitamin deficiencies, diets high in animal fat can contribute to cell injury

Mechanisms of Cell Injury

Cell response to injury depends on type, duration, and severity
Four key intracellular systems vulnerable to injury:
- Cell membrane integrity
- Aerobic respiration
- Protein synthesis
- The genetic apparatus
Calcium Imbalance:
- Cytosolic calcium normally kept low by ATP-dependent transporters
- Ischemia or toxins increase calcium influx and release from mitochondria
- Activated enzymes (phospholipases, proteases, ATPases, endonucleases) damage cell structures
Free Radicals:
- Important mediators of cell death
- Unstable chemical species with unpaired electrons
- Generated during normal metabolism, radiation, chemical exposure
- Damage cell components (lipid peroxidation of membranes, DNA damage, protein cross-linking)

Ischemic and Hypoxic Injury

Reversible Injury:
- Initial effect of hypoxia is reduced ATP production
- Results in sodium and water influx, potassium efflux, cell swelling
- Increased anaerobic glycolysis, glycogen depletion, lactic acid buildup
- Reduced protein synthesis, cytoskeletal damage
Irreversible Injury:
- Severe mitochondrial damage, calcium accumulation
- Extensive plasma membrane damage, lysosomal swelling
- Reperfusion can worsen injury (calcium-mediated)
- Loss of proteins, coenzymes, RNA
- Lysosomal enzymes degrade cell components

Mechanisms of Irreversible Injury

Progressive loss of membrane phospholipids
Cytoskeletal abnormalities (protease activation, calcium increase)
Toxic oxygen radicals generated during reperfusion
Lipid breakdown products with detergent effects

Chemical Injury

Two main mechanisms:
- Direct combination with cellular components (e.g., mercury binding to sulfhydryl groups)
- Conversion to reactive metabolites (e.g., CCl4 converted to CCl3. in the liver, causing lipid peroxidation)

Patterns of Acute Cell Injury

Reversible Cell Injury:
- Light microscopic changes: cell swelling, cytoplasmic eosinophilia, fatty change
- Ultrastructural changes: membrane blebbing, mitochondrial swelling, ER dilatation, nuclear changes
Necrosis:
- Morphologic changes after cell death in living tissue
- Enzymatic digestion of cell and protein denaturation
- Cytoplasmic changes: eosinophilia, vacuolation, calcification
- Nuclear changes: karyolysis, pyknosis, karyorrhexis

Types of Necrosis

Coagulative Necrosis: Preservation of structural outlines (common in myocardial infarction)
Liquefactive Necrosis: Enzymatic digestion, liquefied tissue (bacterial infections, CNS hypoxia)
Gangrenous Necrosis: Ischemic coagulative necrosis with superimposed infection
Caseous Necrosis: Cheese-like appearance, characteristic of tuberculosis

Calcification

Dystrophic Calcification: Deposition in dead or dying tissue (atherosclerosis, aging)
Metastatic Calcification: Deposition in normal tissue due to hypercalcemia (hyperparathyroidism, tumor-related, vitamin D toxicity, renal failure)

Cellular Adaptations of Growth and Differentiation

Atrophy: Reduction in cell size due to decreased work load, blood supply, innervation, nutrition, hormonal stimulation, or aging
Hypertrophy: Increase in cell size due to increased synthesis of proteins and organelles (increased workload)

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Description

This quiz covers the concepts of cell injury, including the mechanisms of necrosis and apoptosis. It discusses various causes of cell injury, ranging from hypoxia to immunologic reactions. Test your understanding of how cells adapt to stress and the factors leading to cell damage.