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تاريخ التسجيل : 18/07/2010
|موضوع: psychoactive drugs 3/9/2010, 14:22|| |
A psychoactive drug, psychopharmaceutical or psychotropic is a chemical substance that crosses the blood-brain barrier and acts primarily upon the central nervous system where it alters brain function, resulting in changes in perception, mood, consciousness, cognition, and behavior. These drugs may be used recreationally, to purposefully alter one's consciousness, as entheogens for ritual or spiritual purposes, as a tool for studying or augmenting the mind, or therapeutically as medication.
Because psychoactive substances bring about subjective changes in consciousness and mood that the user may find pleasant (e.g. euphoria) or advantageous (e.g. increased alertness), many psychoactive substances are abused, that is, used excessively, despite risks or negative consequences. With sustained use of some substances, physical dependence may develop, making the cycle of abuse even more difficult to interrupt. Drug rehabilitation aims to break this cycle of dependency, through a combination of psychotherapy, support groups and even other psychoactive substances.
In part because of this potential for abuse and dependency, the ethics of drug use are the subject of a continuing philosophical debate. Many governments worldwide have placed restrictions on drug production and sales in an attempt to decrease drug abuse. Ethical concerns have also been raised about over-use of these drugs clinically, and about their marketing by manufacturers.
Psychoactive drugs are divided into 3 groups:
• depressants - those that slow down the central nervous system; such as tranquillisers, alcohol, petrol, heroin and other opiates, cannabis (in low doses)
• stimulants- those that excite the nervous system; such as nicotine, amphetamines, cocaine, caffeine
• hallucinogens - those that alter how reality is perceived; such as LSD, mescaline, "magic mushrooms"
General anesthetics are a class of psychoactive drug used on patients to block pain and other sensations. Most anesthetics induce unconsciousness, which allows patients to undergo medical procedures like surgery without physical pain or emotional trauma. To induce unconsciousness, anesthetics affect the GABA and NMDA systems. For example, halothane is a GABA agonist, and ketamine is an NMDA receptor antagonist
Psychoactive drugs are often prescribed to manage pain. As the subjective experience of pain is regulated by endogenous opioid peptides, pain can be managed using psychoactives that operate on this neurotransmitter system as opioid receptor agonists. This class of drugs can be highly addictive, and includes opiate narcotics, like morphine and codeine. NSAIDs, such as aspirin and ibuprofen, are a second class of analgesics. They reduce eicosanoid-mediated inflammation by inhibiting the enzyme cyclooxygenase.
Psychiatric medications are prescribed for the management of mental and emotional disorders. There are 6 major classes of psychiatric medications:
• Antidepressants, which are used to treat disparate disorders such as clinical depression, dysthymia, anxiety, eating disorders and borderline personality disorder
• .Stimulants, which are used to treat disorders such as attention deficit disorder and narcolepsy and to suppress the appetite.
• Antipsychotics, which are used to treat psychoses, schizophrenia and mania.
• Mood stabilizers, which are used to treat bipolar disorder and schizoaffective disorder.
• Anxiolytics, which are used to treat anxiety disorders.
• Depressants, which are used as hypnotics, sedatives, and anesthetics.
• Stimulants, which activate the central nervous system. These are used recreationally for their euphoric effects.
• Hallucinogens (psychedelics, dissociatives and deliriants), which induce perceptual and cognitive distortions.
• Hypnotics, which depress the central nervous system. These are used recreationally because of their euphoric effects.
• Opioid Analgesics, which also depress the central nervous system. These are used recreationally because of their euphoric effects.
• Inhalants, in the forms of gas aerosols, or solvents, which are inhaled as a vapor because of their stupefying effects. Many inhalants also fall into the above categories (such as nitrous oxide which is also an analgesic).
Psychoactive drugs operate by temporarily affecting a person's neurochemistry, which in turn causes changes in a person's mood, cognition, perception and behavior. There are many ways in which psychoactive drugs can affect the brain. Each drug has a specific action on one or more neurotransmitter or neuroreceptor in the brain
.Drugs that increase activity in particular neurotransmitter systems are called agonists. They act by increasing the synthesis of one or more neurotransmitters or reducing its reuptake from the synapses. Drugs that reduce neurotransmitter activity are called antagonists, and operate by interfering with synthesis or blocking postsynaptic receptors so that neurotransmitters cannot bind to them
•·.·´¯`·.·• (عضو سوبر) •·.·´¯`·.·•
عدد الرسائل : 888
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تاريخ التسجيل : 25/03/2008
|موضوع: رد: psychoactive drugs 3/9/2010, 15:10|| |