Inhalants cross which barrier?

Inhalants cross which barrier?

• A. Blood-brain barrier
• B. Placental barrier
• C. Blood-testes barrier
• D. Gastrointestinal barrier

Answer: (A)

The main idea being tested is how substances reach the brain and which protective barrier governs their access to the CNS. Inhalants exert their effects so quickly because they are inhaled and rapidly absorbed through the lungs into the bloodstream. Once in circulation, their high lipid solubility allows them to diffuse readily across the blood-brain barrier, a selective wall of tightly joined cells that normally limits what enters the brain. Lipid-soluble substances cross this barrier easily, so inhalants produce fast central nervous system effects. The other barriers mentioned serve different protective roles and aren’t the routes that explain the rapid CNS action of inhalants. The gastrointestinal barrier would be relevant if the substance were taken orally, but inhalants bypass the gut. The placental barrier and the blood-testes barrier protect fetus and testicular tissue, respectively, and aren’t the primary reasons inhalants affect the brain quickly.

The main idea being tested is how substances reach the brain and which protective barrier governs their access to the CNS. Inhalants exert their effects so quickly because they are inhaled and rapidly absorbed through the lungs into the bloodstream. Once in circulation, their high lipid solubility allows them to diffuse readily across the blood-brain barrier, a selective wall of tightly joined cells that normally limits what enters the brain. Lipid-soluble substances cross this barrier easily, so inhalants produce fast central nervous system effects.

The other barriers mentioned serve different protective roles and aren’t the routes that explain the rapid CNS action of inhalants. The gastrointestinal barrier would be relevant if the substance were taken orally, but inhalants bypass the gut. The placental barrier and the blood-testes barrier protect fetus and testicular tissue, respectively, and aren’t the primary reasons inhalants affect the brain quickly.