Cyanide Poisoning and Types of Insults

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Questions and Answers

What is the primary difference between ischemia and hypoxia?

Hypoxia affects anaerobic energy generation, whereas ischemia does not

Hypoxia is a type of ischemia

Ischemia is a type of hypoxia

Ischemia affects anaerobic energy generation, whereas hypoxia does not (correct)

What is a consequence of the failure of the Na/K pump in hypoxic cells?

Cell swelling (correct)

Reduced ATP production

Cell shrinkage

Increased protein synthesis

What is the result of clumped nuclear chromatin in hypoxic cells?

Cell cycle arrest

Apoptosis (correct)

Necrosis

Abnormal nuclear division

What is the primary mechanism of cell injury in ischemia?

Loss of ATP generation Signup and view all the answers

What is the final consequence of severe and prolonged cell injury?

Necrosis Signup and view all the answers

What is the primary difference between reversible and irreversible cell injury?

Reversible injury can recover with removal of the injurious agent, while irreversible injury cannot Signup and view all the answers

Which of the following types of cells are highly susceptible to ischemic damage?

Neurons Signup and view all the answers

What is the term for reduced oxygen carrying capacity of blood?

Hypoxaemia Signup and view all the answers

What is the term for cellular death that occurs due to severe cellular injury?

Necrosis Signup and view all the answers

Which of the following factors does NOT influence the severity of cell injury?

Age of the individual Signup and view all the answers

Which of the following is a characteristic of cellular swelling (hydropic change) in hepatocytes?

Cytoplasmic pallor due to accumulated water Signup and view all the answers

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

Necrosis Signup and view all the answers

Which of the following enzymes is leaked into the circulation during tissue-specific necrosis of cardiac muscle?

Creatine kinase Signup and view all the answers

What is the primary cause of lethal cell damage in ischemic injury?

All of the above Signup and view all the answers

Which of the following is a common feature of non-ischaemic cell injury?

All of the above Signup and view all the answers

Study Notes

Types of Insults

Chemical: drugs (e.g. paracetamol overdose), alcohol, cigarette smoke, and many more
Infections: Eukaryotes (Fungi, Protozoa), Prokaryotes (Bacteria, Rickettsiae, Chlamydiae), Viruses (DNA, RNA)
Physical: direct physical effects (e.g. extreme heat or cold, sudden changes in pressure, electrical currents)
Immune: Humoral and Cell-mediated
Nutrition: dietary insufficiency and excess

Principle Structural Targets for Cell Damage

Cell membranes: Plasma membrane, Organellar membranes
DNA
Proteins: Structural, Enzymes
Mitochondria: oxidative phosphorylation

Cell Injury and Necrosis

Ischemic and Hypoxic Injury: ischemia is the most common cause of cell injury in clinical medicine
Ischemia vs. Hypoxia: in ischemia, energy generation by anaerobic glycolysis stops due to the cut-off of blood supply, whereas in hypoxia, energy generation can continue
Ischemia injures tissues faster than hypoxia

Hypoxia and Ischemia

Loss of ATP Generation: failure of many energy-dependent systems of the affected cell
Failure of ion pumps: leading to cell swelling, influx of Na+ and Ca++, and exit of K+
Anaerobic Glycolysis: depletion of glycogen stores with accumulation of lactic acid
Reduction in Protein Synthesis: altered metabolism leading to abnormal accumulations

Pathogenesis of Cell Injury - Hypoxia

Reversible:
- Loss of ATP
- Failure of Na/K pump
- Anaerobic metabolism
- Increased lactic acid and phosphate
- Clumped nuclear chromatin
- Reduced protein synthesis
Irreversible:
- Massive intra-cytoplasmic calcium accumulation
- Activation of multiple degradative enzymes
- Lethal cell damage

Cellular Swelling (Hydropic Change)

Affected hepatocytes are distended by accumulated water, imparting cytoplasmic pallor
Histologic appearance of hepatic fatty change: lipid accumulates in hepatocytes as vacuoles with clear appearance on H&E staining

Consequences of Ischemia

Irreversible injury and necrosis: associated with severe swelling of mitochondria and lysosomes, extensive damage to plasma membranes, and widespread leakage of cellular enzymes into the extracellular space
Massive influx of calcium into the cell may occur
Death is mainly by necrosis, but apoptosis also occurs

Detection of Tissue-Specific Necrosis

Leakage of intracellular proteins through damaged cell membranes into the circulation provides a means of detecting tissue-specific necrosis using blood or serum samples
Examples: cardiac muscle (creatine kinase and troponin), hepatocytes (transaminases)
Measurement of serum levels is used clinically to assess damage to these tissues

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, including chemicals/drugs, reperfusion injury, inflammation, irradiation, oxygen toxicity, and carcinogenesis
Free radical generation occurs by cellular injury

Cell Injury and Death

Occurs when the limits of adaptive capability are exceeded
Cell injury is divided into reversible and irreversible (cell death)
Reversible cell injury occurs when the injurious agent is mild or short-lived
Irreversible cell injury occurs when the injury becomes severe and the cell cannot recover

Factors Influencing Severity of Injury

Type and severity of injurious agent
Duration of exposure
Type of affected cells (e.g. neurons, myocardial cells, hepatocytes, skeletal muscles, epidermis, fibroblasts)
Susceptibility of cells to injury varies, with neurons being highly susceptible to ischemic damage and skeletal muscles being less susceptible

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Description

This quiz covers the different types of insults that can cause cyanide poisoning, including chemical, infections, physical, immune, and nutritional insults. It explains the various ways in which these insults can occur, such as through drug overdose, infections, and physical effects.