Heroin is a drug made from morphine. Morphine comes from opium poppy, which grows throughout the Middle East. Opium is one of the original pain-relief drugs. It affects cells in the brain, turning down pain signals as well as increasing “feel good” brain chemicals.
Heroin does the same thing. It makes users feel both happy and pain-free. When heroin is used, it converts back into morphine inside the body. Morphine binds with opioid receptors which suppress pain signals from the body. When you break your ankle, pain fibers send the pain signals to your brain, which tells you to stop moving because you have an injury. Without a working pain system, you could damage your body permanently. Pain is your body’s way of making you stop and take care of yourself.
Opioid receptors are primarily located in the brain stem. This is the part of your central nervous system that regulates automatic life functions, including breathing, blood pressure and other functions. When you take too much heroin, these systems become suppressed. That’s why people die from heroin overdoses. Too much heroin can stop your breathing.