Toxicity Pathways Quiz

Pathways to Toxicity

• Toxicity can occur through various pathways, including direct interaction with a target molecule or adverse effects on the biological environment.
• The puffer fish poison, tetrodotoxin, is an example of direct toxicity through interaction with voltage-gated Na+ channels.
• The chemical 2,4-dinitrophenol causes toxicity by collapsing the proton gradient in mitochondria.
• Renal tubule blockage is another example of toxicity through adverse effects on the environment.
• The most complex pathway to toxicity involves four steps: delivery, interaction with target molecules, perturbations in cell function and/or structure, and repair or adaptive mechanisms that can become malfunctional.
• The intensity of a toxic effect depends on the concentration and persistence of the ultimate toxicant at its site of action.
• The ultimate toxicant can be the parent compound, a metabolite, a reactive oxygen/nitrogen species, or an endogenous molecule.
• The accumulation of the ultimate toxicant at its target depends on various processes that increase or decrease its concentration.
• Transporters can facilitate gastrointestinal absorption of some chemicals, but the majority of toxicants diffuse through cells.
• Presystemic elimination can decrease the systemic availability of toxicants, but it may contribute to injury of digestive mucosa, liver, and lungs.
• Distribution of toxicants to target sites can be facilitated or hindered by various mechanisms.
• Detoxication and toxication are biotransformation mechanisms that eliminate or create ultimate toxicants, respectively.