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Psychoactive drugs: Stimulants

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Carole Yue.

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Video transcript

- [Voiceover] We talked about depressants, which depress neural activity and bodily functions. On the other hand, we have stimulants, which stimulate or intensify neural activity and bodily functions. These can range from your everyday stimulants, like caffeine, to more hardcore drugs, like cocaine, amphetamines, methamphetamines and ecstasy. In between those extremes are nicotine, which is found in cigarettes. If you've ever tried to stay awake by drinking coffee or a soda or something like that, then you know that caffeine adds energy and can disrupt your sleep for several hours. Nicotine actually acts similarly. It increases your heart rate and blood pressure and arouses the brain to a state of heightened alertness. Nicotine also suppresses your appetite, which is one reason that people sometimes gain weight when they quit smoking. Without the nicotine, their appetite return, so they eat more. In very high levels, nicotine can actually cause muscles to relax and cause the release of certain neurotransmitters that may reduce stress. That's your body's natural response to try to counteract all that heightened alertness and tension caused by the nicotine. Both caffeine and nicotine are physiologically addictive, meaning that your body grows accustomed to them and starts to experience negative reactions when you don't get enough. For example, you might know people who drink a lot of coffee everyday, or you might be one of those people. If you don't get your coffee, think about if you experience any headaches, irritability, difficulty concentrating, even depression. That's withdrawal symptom from the caffeine and coffee. Nicotine is even more addictive than that. This is one reason that it's so hard to quit smoking. Once the body gets used to nicotine, its absence can lead to withdrawal symptoms like anxiety, insomnia, distractibility, and irritability. Cocaine is an even stronger stimulant. It causes your brain to release so much dopamine, serotonin and norepinephrine that it basically depletes your brain's supply. Once the drug wears off, you experience this intense crash and become very depressed. Regular cocaine users can experience emotional disturbances, suspicion, convulsions, cardiac arrest, or respiratory failure. Amphetamines and methamphetamines also trigger the release of dopamine, and meth can cause a feeling of euphoria that can last up to eight hours, but after that wears off, people experience, again, intense irritability, insomnia, or even seizures and depression. Meth is highly addictive, and people will literally just devote their lives to getting another fix. Long-term addicts might even lose the ability to maintain normal levels of dopamine, as their brain tries to adjust to the intense highs.