澳洲皇家墨尔本理工大学论文代写:毒品
一些药物（例如大麻和海洛因）具有与由脑自然产生的神经递质（化学信使）相似的作用。其他药物，如可卡因或甲基苯丙胺，可以导致神经细胞释放大量的天然神经递质主要是多巴胺或防止这些天然神经递质的再生，其用于停止神经元之间的信号传导。多巴胺负责控制运动，动机，情感和感觉。大量的多巴胺的释放产生欣快的效果（例如放松，焦虑减轻，应力消除，情绪抬升等）。这种药物的效果或采取这种物质后的感觉在大脑中设置了一个信号，使人们想要重复的药物的奖励行为。如果该人继续使用药物，脑适应大量的多巴胺，并试图通过产生较少的多巴胺或通过减少脑中多巴胺受体的数目来克服压倒性的效应。这导致在奖励回路中多巴胺的作用降低，并且这减少了滥用药物的人享受药物的能力和先前从药物中获得的效果。这使得人继续滥用药物以便获得多巴胺的效果，但是需要大量的药物来实现多巴胺的相同的先前效果，这被称为耐受效应。长期滥用导致大脑的其他化学系统的变化和奖励回路。谷氨酸是一种神经递质，影响人和神经系统的学习能力的奖励电路。当通过药物滥用达到谷氨酸的最大浓度时，大脑试图改变这种情况，这可能损害滥用者的精神功能。这可能导致设计用于判断，决策，学习，记忆控制和行为控制的大脑区域的变化。这些改变可以使滥用者继续服用药物，因为尽管滥用者具有不良作用，但是其心理作用。
Some drugs (e.g., marijuana and heroin) have effects similar to neurotransmitters (chemical messengers) which are naturally produced by the brain. Other drugs, such as cocaine or methamphetamine, can cause the nerve cells to release large amounts of natural neurotransmitters mainly dopamine or to prevent the regeneration of these natural neurotransmitters, which is used to stop the signalling between the neurons. Dopamine is responsible for controlling movement, motivation, emotion and feelings. The release of the large amount of dopamine produces euphoric effects (such as relaxation, anxiety relief, stress relief, mood lift etc.). The effect of this drug or the feeling after taking this substance sets a signal in the brain that makes people want to repeat the rewarding behaviour of the drugs. If the person continues to use the drugs, the brain adapts to the large amount of dopamine and tries to overcome the overwhelming effect by producing less dopamine or by reducing the number of dopamine receptors in the brain. This results in the effect of dopamine being reduced in the reward circuit, and this reduces the person abusing the drugs ability to enjoy the drug and the effect that was previously derived from the drug. This makes the person to continue abusing the drug so as to get the effect of dopamine back but large amount of the drug will be needed to achieve the same previous effect of dopamine and this is known as the tolerance effect. Long-term abuse causes changes in other chemical systems of the brain and reward circuits also. Glutamate is a neurotransmitter that influences the reward circuit of a person’s ability to learn. When the maximum concentration of glutamate is reached by drug abuse, the brain attempts to change this, which can damage the mental function of the abuser. This can lead to changes in areas of the brain that are design for judgment making , decision making, learning, memory control and behaviour control. These changes can make the abuser continue taking the drugs because of the psychological effects despite the adverse effects the abuser is having.
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