2. what does heroin do to the brain, and what are it's short-term and long-term effects on the brain, the rest of the body, or the mind? write at least 3 sentences on this topic that seventh graders could understand.

Heroin binds to and activates specific receptors in the brain called mu-opioid receptors (MORs). Our bodies contain naturally occurring chemicals called neurotransmitters that bind to these receptors throughout the brain and body to regulate pain, hormone release, and feelings of well-being. When MORs are activated in the reward center of the brain, they stimulate the release of the neurotransmitter dopamine, causing a reinforcement of drug taking behavior.

Explanation:

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b) the heart is a pump made of muscle and that is difficult to grow in the lab.