Where is nitrous oxide excreted from the body?

• A. Urine
• B. Lungs
• C. Intestines
• D. Skin

Answer: (B)

Nitrous oxide is primarily excreted from the body through the lungs. Upon inhalation, nitrous oxide is quickly absorbed into the bloodstream and, once the administration ceases, it is rapidly eliminated from the body via exhalation. This route of excretion is efficient due to the gas's low solubility in blood, which allows it to diffuse quickly back into the lungs for elimination.

While other substances are excreted through urine, intestines, or skin, these routes do not apply to nitrous oxide, which is favored for its gaseous properties and how it swiftly leaves the body after use. The mechanism behind its excretion plays a crucial role in its effectiveness as a sedative and analgesic agent during dental and medical procedures.