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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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  • blobby green style avatar for user Catherine Brizzo
    How long does the effect of cocaine last after, let's say, one line of cocaine?
    (6 votes)
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  • piceratops tree style avatar for user BVK
    How does nicotine inhibe appetite?
    (2 votes)
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  • male robot johnny style avatar for user Gyroscope99
    In another video it is mentioned that cocaine prevents the reuptake of dopamine from the synaptic clefts of neurons, whereas this video states that more dopamine is released. I was just wondering if anyone knew which mechanism is at play, or perhaps both are because either mechanism can deplete the body's dopamine levels?
    (3 votes)
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    • leafers ultimate style avatar for user William H
      On one side of the cleft where the dopamine is released there also transporters which take dopamine back inside. Cocaine blocks these transporters and causes more and more dopamine to flood the synapse without being taken back up. However, cocaine also sets of dopamine in reward pathways causing addiction.
      (5 votes)
  • piceratops tree style avatar for user Anthony Blackburn
    Would it be more appropriate to say that caffeine alters one's perception of fatigue rather than indicating it increases energy? Caffeine is a competitive inhibitor of AMP receptors. AMP receptors are involved with the feeling of being tired. When AMP levels are high (low energy state), it becomes more likely that they will bind to AMP receptors. This elicits a feeling of fatigue. However, when caffeine is present it competes for the AMP receptors. As such, the perception of feeling tired is blunted because caffeine does not indicate a low energy state like the binding of AMP does.
    (3 votes)
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  • mr pants teal style avatar for user luna lovegood
    Why would someone eat more because of nicotine aka smoking if at the drawing showed a down arrow next to appetite?? This is confusing. Don't you need an actual appetite to eat? I don't get it at all......
    (2 votes)
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  • leaf red style avatar for user Cristina BA
    I would like to know how, in big dosis, a drug which is estimulating can causes a relaxing effect. Thank you so much! Excelent lessons and excelent website!! =)
    (2 votes)
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  • leaf red style avatar for user ahmed khatab
    psychoactive drugs mean that drugs function on central neurotransmitters like dopamine and serotonin...or function on CNS and bodily functions...?
    (2 votes)
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  • orange juice squid orange style avatar for user eirousseau
    There was a correction to establish that cocaine prevents reuptake of dopamine and not that it causes the release of more. Then the video goes on and likens the mechanism of amphetamines to cocaine by saying that it "also" induces dopamine release. Since the first assertion was actually not exactly right, can someone lemme know if the mechanism of meth is actually also inhibited reuptake, as opposed to increased release? Muchas Gracias.
    (2 votes)
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  • spunky sam blue style avatar for user Ellen Seppings
    how much coffaine is in coffee
    (1 vote)
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  • piceratops seed style avatar for user Radhika Chitale
    Is there any drug that is both depressant and stimulant or which is either?
    (2 votes)
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    • aqualine ultimate style avatar for user Rachel  Reiff
      As far as I know there is no such thing, however it is very common to pair both as separate drugs/substances. This is because it can "counteract" or "enhance" how a person may react. For example a drunk person may drink an energy drink to feel more alert and awake, although their central nervous system is still depressed, or may take wild swings between being stimulated and depressed. Although I guess the only exception to this is caffeine, having been shown to depress a stimulated nervous system (specifically those with ADHD) and also Marijuana depending on the person even though it is more of a hallucinogen.
      (1 vote)

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.