Which organ is primarily responsible for turning toxic substances into non-toxic forms for elimination?

• A. Kidney
• B. Liver
• C. Heart
• D. Lungs

Answer: (B)

Detoxification is handled mainly by the liver, which uses a range of enzymes to transform lipophilic toxins into forms that are easier to eliminate. Through Phase I reactions, the liver introduces or exposes functional groups on a toxin, often by oxidation, reduction, or hydrolysis. Then Phase II reactions attach polar groups through conjugation (such as glucuronidation, sulfation, or glutathione conjugation). These changes make the substance more water-soluble, so it can be excreted in urine or bile. The kidneys do the job of filtering waste from the blood and removing it in urine, but they don’t primarily modify toxins. The lungs can expel some volatile substances by breathing, and the heart’s job is circulation. So the liver is the central organ responsible for turning toxic substances into forms that can be eliminated.