Cell Injury and Apoptosis

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Questions and Answers

What is the main difference between ischemia and hypoxia?

Ischemia generates more ATP than hypoxia

Ischemia is a type of hypoxia

Ischemia interferes with the delivery of substrates for glycolysis (correct)

Hypoxia is a type of ischemia

What is the primary effect of anaerobic glycolysis in hypoxic cells?

Increased protein synthesis

Increased ATP production

Depletion of glycogen stores (correct)

Reduced lactic acid accumulation

What is the result of paralysis of ion pumps in hypoxic cells?

Exit of Na+ and influx of K+

Reduced protein synthesis

Increased ATP production

Influx of Na+ and exit of K+ (correct)

What is the consequence of reduced protein synthesis in hypoxic cells?

Altered metabolism leading to abnormal accumulations Signup and view all the answers

What type of insult can result from extreme heat or cold?

Physical insult Signup and view all the answers

What is a common target of cell damage?

Cell membranes Signup and view all the answers

What is the result of ischemic injury in tissues?

Anaerobic energy generation stops Signup and view all the answers

What is a type of cell injury that can result from dietary insufficiency?

Nutritional injury Signup and view all the answers

What happens when the limits of adaptive capability are exceeded?

Cell injury occurs Signup and view all the answers

What is reversible cell injury characterized by?

Functional and morphologic changes that are reversible Signup and view all the answers

What type of injurious agent can cause cell injury?

Chemical agents Signup and view all the answers

What factor influences the severity of cell injury?

Type of affected cells Signup and view all the answers

Which cell type is highly susceptible to ischemic damage?

Neurons Signup and view all the answers

What is ischemia?

Local or systemic inadequate oxygenation of tissues Signup and view all the answers

What can interfere with oxidative phosphorylation?

Poisonous substances Signup and view all the answers

What happens with continuing damage?

The injury becomes irreversible Signup and view all the answers

What is the primary cause of cellular swelling in hypoxic injury?

Accumulation of water in the cytoplasm Signup and view all the answers

What is the hallmark of hepatic fatty change?

Lipid accumulation in the hepatocytes as vacuoles Signup and view all the answers

What is the fate of the cell if oxygen is restored after a period of hypoxia?

All disturbances are reversible Signup and view all the answers

What is the primary mechanism of cell death in ischemic injury?

Necrosis Signup and view all the answers

What is the significance of measuring serum levels of creatine kinase and troponin?

To detect tissue-specific necrosis in the heart Signup and view all the answers

What is the consequence of massive influx of calcium into the cell?

Activation of degradative enzymes Signup and view all the answers

What is the common feature of free radicals?

They are highly reactive and unstable Signup and view all the answers

What is the consequence of reduced ATP synthesis and mitochondrial damage?

Irreversible injury and cell death Signup and view all the answers

Study Notes

Cellular Injury

Cellular injury occurs when the limits of adaptive capability are exceeded and no adaptive response is possible.

Types of Cell Injury

Cell injury can be divided into reversible and irreversible (cell death) types.

Reversible Cell Injury

Occurs when the injurious agent is mild or short-lived, and functional and morphologic changes are reversible.
Cell injury becomes irreversible with continuing damage, leading to cell death.

Types of Injurious Agents (Causes of Cell Injury)

Hypoxia
Physical agents (trauma, burns, irradiation)
Chemical agents (poisons, drugs, alcohol)
Infectious agents
Immunological reactions
Genetic derangement
Nutritional imbalances
Aging

Factors Influencing Severity of Injury

Type and severity of injurious agent
Duration of exposure
Type of affected cells (e.g., neurons, myocardial cells, skeletal muscles)

Types of Insult

Hypoxia

Reduced oxygen
Ischaemia (local or systemic)
Hypoxaemia (inspired oxygen too low, diffusion barrier abnormal, or insufficient carrying capacity in blood)
Interference with oxidative phosphorylation (e.g., cyanide poisoning)

Chemical Insults

Drugs (e.g., paracetamol overdose)
Other chemicals (e.g., alcohol, cigarette smoke)

Infections

Eukaryotes (Fungi, Protozoa)
Prokaryotes (Bacteria, Rickettsiae, Chlamydiae)
Viruses (DNA, RNA)

Physical Insults

Direct physical effects (extreme heat or cold, sudden changes in pressure, electrical currents)

Immune Insults

Humoral
Cell-mediated

Nutritional Insults

Dietary insufficiency
Dietary excess

Principle Structural Targets for Cell Damage

Cell membranes (plasma membrane, organellar membranes)
DNA
Proteins (structural, enzymes)
Mitochondria (oxidative phosphorylation)

Examples of Cell Injury and Necrosis

Ischemic and Hypoxic Injury

Ischemia is the most common cause of cell injury in clinical medicine.
Ischemia injures tissues faster than hypoxia due to lack of substrate delivery for glycolysis.

Hypoxia and Ischemia

Loss of ATP generation leads to failure of many energy-dependent systems.
Anerobic glycolysis leads to lactic acid accumulation and cell swelling.
Reduction in protein synthesis and altered metabolism occur.

Pathogenesis of Cell Injury - Hypoxia

Reversible

Loss of ATP
Failure of Na/K pump leading to cell swelling
Anaerobic metabolism and increased lactic acid
Reduced protein synthesis and altered metabolism

Irreversible

Massive intra-cytoplasmic calcium accumulation
Activation of multiple degradative enzymes
Lethal cell damage

Pathogenesis of Cell Injury - Non-Ischaemic

Reduced ATP synthesis/mitochondrial damage
Loss of calcium homeostasis
Disrupted membrane permeability
Free radicals

Free Radicals

Highly reactive, unstable chemicals associated with cell injury in many settings.
Free radical generation occurs through various mechanisms.

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Description

This quiz covers the key features, causes, and morphological changes of cell injury and apoptosis. It outlines the differences between reversible and irreversible cell death.