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Canada (161,929)
Psychology (9,695)
PSYC62H3 (313)
Chapter 9

chapter 9

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Department
Psychology
Course
PSYC62H3
Professor
Suzanne Erb
Semester
Winter

Description
Chapter 9 PSYCHOSTIMULANTS Psychostimulants, in low to moderate doses, these drugs produce heightened mood (at its extreme, it is described as euphoria), increase vigilance and alertness, and reduce fatigue and the tendency to sleep. These properties also results in enhanced performances on a variety of tasks, althought the dose response functions are inverted U- or J-shaped. That is, there are a range of doses in which enhancement occurs, but as the dose increases beyond this range, performances return to nondrug levels or worsens. ( heart rate and BP) Other frequently used terms for these drugs are behavioural stimulants and CNS stimulants; however, these terms do not do justice to the actual common properties of these drugs. Some behaviour may increase while others may decrease, depending on the dose and the frequency of the behaviour typically observed without the drugs and depending on the person. The same applies to the neuron activity within the CNS. None of these terms mentioned adequately describes the effects of these drugs if the drugs are used in large amounts acutely or moderate amounts chronically. Within this category are several structurally different types of drugs, most common = caffeine. Then you have nicotine, and then you have amphetamines together with other structurally related drugs, comprise another popular class. These include methyphenidate (proprietary name, Ritalin) and pemoline (Cylert), which are structurally and pharmacologically similar to the amphetamines. Cocaine is perhaps the most notorious of the groups Caffeine Caffeine is the most widely used behaviourally active drug in the world It is one of several substances referred to as methylxanthines. www.notesolution.com Typical adult in US consumes about 200-300mg of caffeine a day. Based on typical pattern of use throughout the day and a plasma half-life of ~ 5 hours, peak caffeine plasma levels typically occur in the early evening. It is difficult to determine the overall time course and impact of caffeine on an individual as they differ. In intravenous drug self-administration experiments with animals, caffeine has been shown to have reinforcing effects in some cases but not in others. Most evidence suggests that caffeine is rated as having the most desirable and pleasant reactions in heavy coffee drinkers, particularly after they have not had any coffee for several hours and some people show normally show dysphoric effect for coffee in general. This finding suggests that many of the reinforcing effects of caffeine stem from its ability to terminate caffeine withdrawal. However, research indicates that the average caffeine intake of coffee consumers does not predict the occurrence of withdrawal When coffee consumers are tested with caffeinated and decaffeinated coffee, they were more likely to self-administer caffeinated coffee. The effects of caffeine vary considerably among individuals in terms of wakefulness, psychomotor coordination, mood alterations, and autonomic nervous system response. Two cups of coffee, which contains ~ 150 mg of caffeine, has the mood-elevating and fatigue-relieving properties of threshold doses of amphetamine (~ 2 to 5mg) However, larger doses generally do not have more of a mood-elevating effect, and 7 to 10 cups of coffee may cause insomnia, restlessness, mild sensory disturbances, or muscle tenseness ( collectively called caffeinism), or may precipitate anxiety or panic attacks in susceptible individuals Caffeine typically raises BP slightly in both men and women, but apparently via different mechanisms. Heart rate changes are variable and with some caffeine doses, may actually decrease. Increases in galvanic skin conductance level and reactivity are generally noted. www.notesolution.com
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