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The effect of drugs on the nervous system

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The effect of drugs on the nervous system A drug is defined as a substance that, when absorbed into the body, alters a normal bodily function. Some are able to do this, as they are capable of producing an array of different effects on the nervous system. The reason why affecting the nervous system of an organism is potentially so significant is due to the nature of it. The fact the nervous system directs the functions of all the tissues of the body demonstrates its considerable role within the body. It can therefore be assumed that taking substances which affect how it works may lead to a distortion in the way your body is run, producing unsafe side effects. The term nervous system is actually used to describe two divisions. The central nervous system (CNS) is the part which contains the brain and spinal cord. The peripheral nervous system (PNS) however, consists of all the sensory neurones used to detect stimuli. The PNS receives thousands of sensory inputs and transmits them to the brain via the spinal cord. ...read more.


Alcohol functions as it does on the nervous system by inhibiting the release of neurotransmitters from the pre-synaptic neurones. This ultimately leads to less of the receptors on the post-synaptic neurone being activated. Like most drugs, the effect of alcohol on the body depends strongly on the dosage. A small amount may lead to a dulling of reactions and reflexes, lessening coordination and balance. In higher doses, the symptoms may become much for severe, and potentially very dangerous. Vomiting, nausea and loss of consciousness are all side effects from having too much alcohol. The drug valium also possesses sedative qualities, as well as being an anxiolytic, anticonvulsant and hypnotic drug. On the contrary to alcohol, amphetamines are stimulants. They produce increased wakefulness and focus in association with decreased fatigue and appetite. They work by increasing the synaptic activity of the dopamine and norepinephrine neurotransmitters. Amphetamines initiate the release of dopamine from axon terminals, in addition to inhibiting the breaking down of dopamine in the synaptic cleft by the enzymes. ...read more.


These work by mimicking neurotransmitters at the receptors. This then causes more receptors to become activated. By binding to nicotinic acetylcholine receptors, nicotine increases the levels of several neurotransmitters - acting as a "volume control". It is thought that increased levels of dopamine in the the brain are responsible for the euphoria, relaxation and eventual addiction caused by nicotine consumption. The active drug in cannabis, THC, acts as a partial agonist, having both psychoactive and somatic (leaves user with dry mouth, increased heart rate etc) effects. By changing the frequency of action potentials in the post-synaptic neurone, drugs are able to induce a number of different effects. A chemical may copy or mimic a neurotransmitter or stimulate the production of more neurotransmitters, causing more frequent action potentials. Alternatively, drugs may inhibit the enzyme that deactivates the neurotransmitter. This would allow for the same neurotransmitter molecule to be reused. Finally, drugs may also cause a decrease in the frequency of action potentials in neurones by the inhibiting the release of the neurotransmitters or by blocking the Na+/K+ ion channels on the post-synaptic neurones. ...read more.

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Overall a very good piece.The introduction is good, but does not set up what the candidate is trying to investigate very clearly. Too much wording in places that could be cut down significantly to make the response clearer. Uses awkward ...

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Response to the question

Overall a very good piece.The introduction is good, but does not set up what the candidate is trying to investigate very clearly. Too much wording in places that could be cut down significantly to make the response clearer. Uses awkward terms in the introduction rather than straight scientific facts. Conclusion is adequate but brings in one or two scientific things that are not explained a great deal in the main body of text. The main body of the text is very well analysed and shows scientific thinking that is beyond a level in places.

Level of analysis

Level of analysis and communication is very good. Describes the PNS and CNS very well. When it says that the neurotransmitters in the brain are not well known and the mechanisms of neurotransmitters are also not well known this is wrong as whilst the mechanism of neurotransmitters is not well described at a level, it is well researched at university level. Also breaks down the neurotransmitters into three different ones when in fact there are more neurotransmitters such as VIP, substance P, glutamate and GABA. Provides different examples of drugs and how they effect the nervous system, however I would like to see the different side effects explained more clearly rather than just being listed. Does not explain the difference between agonists, antagonists, partial agonists and so forth very well.

Quality of writing

Grammar is good, but one or two awkwardly worded sentences meaning that the sentence is slightly unclear to the reader in the introduction. Spelling and punctuation very good.

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Reviewed by skatealexia 06/03/2012

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