General mechanisms by which toxins damage cells (oxidative stress, enzyme inhibition, membrane disruption) tested at the introductory toxicology level.
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- What is oxidative stress?
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An imbalance between reactive oxygen species production and antioxidant defenses, favoring damage.- What are reactive oxygen species (ROS)?
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Chemically reactive molecules containing oxygen, such as superoxide and hydroxyl radical.- What is a free radical?
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A molecule with an unpaired electron, making it highly reactive.- What is the primary intracellular antioxidant that protects cells from oxidative damage?
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Glutathione (GSH).- What happens to a cell when its glutathione stores are depleted by a toxin?
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The cell becomes more vulnerable to oxidative damage.- What is lipid peroxidation?
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Oxidative degradation of lipids in cell membranes by free radicals.- What is the main consequence of lipid peroxidation for a cell membrane?
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Loss of membrane integrity and increased permeability.- How does carbon tetrachloride cause liver cell injury?
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It is bioactivated to a trichloromethyl free radical that triggers lipid peroxidation.- What is enzyme inhibition as a mechanism of cellular toxicity?
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A toxin binds to an enzyme and blocks its normal catalytic activity.- Organophosphate pesticides inhibit which enzyme?
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Acetylcholinesterase.- What happens when acetylcholinesterase is inhibited?
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Acetylcholine accumulates at synapses, causing overstimulation.- How does cyanide poison cells?
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It inhibits cytochrome c oxidase (complex IV), blocking cellular respiration.- What is the result of cytochrome c oxidase inhibition by cyanide?
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Cells cannot use oxygen to produce ATP, causing histotoxic hypoxia.- How does carbon monoxide impair oxygen delivery to tissues?
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It binds hemoglobin with much higher affinity than oxygen, forming carboxyhemoglobin.- What is membrane disruption as a toxic mechanism?
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Damage to the structural integrity of the cell membrane, causing loss of its selective permeability.
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