Blood never leaves the blood vessels and does not exchange substances directly with cells. rather it exchanges substances with which then exchanges with cells.

Matching: 1. first used by europeans as a local anesthetic; now abused for its euphoric effects 5 marijuana 2. found in coffee beans, tea leaves, and cocoa beans 2 heroin 3. prescribed for pain involving serious injury or surgery 1 morphine 4. illegal derivative of morphine that is sold on the street as a white powder 6 caffeine 5. can evoke feelings of terror and panic 4 lsd 6. causes user to experience a conscious dreamlike state 3 cocaine