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Written Assignment 2 Question 1 The human nervous system is responsible for monitoring and controlling almost all organ system via a series of negative / positive feedback loops. The CNS (central nervous system) includes the brain and spinal cord. The Peripheral Nervous System (PNS) connects the central nervous system to other parts of the organism. The SNS includes all nerves that control the muscular system and external sensory receptors. The Autonomic Nervous System is the part of PNS that comprises of motor neurons controlling internal organs. The ANS consists of two subsystems, the Sympathetic Nervous System that is involved in the fight or flight response and the Parasympathetic Nervous System that is involved in relaxation.
The major structures of brain are: (Denning, Little and Glickman) The life cycle of neurotransmitters: biosynthesis, storage, release, and degradation or re-uptake (Denning, Little and Glickman). Psychoactive drug affects the central nervous system where it alters brain function, leads to temporary changes in perception, mood, consciousness and behavior. Psychoactive drug affects neurotransmitter function; it can lead to more or less of a neurotransmitter release at synapses; can lead to blockage of reuptake of a neurotransmitter by presynaptic cells; and stimulate or block neurotransmitter receptors on postsynaptic cells. Question 4 Prolonged use of benzodiazepines can result in physical dependence even at doses recommended for medical treatment. At the same time, psychological addiction to barbiturates usually develops more quickly than physical dependence. GABA (g-aminobutyric acid) functions as an inhibitory neurotransmitter of the central nervous system.
Benzodiazepines enhance the ability of GABA, the inhibitory neurotransmitter, to activate a type of receptors known as GABA-A receptors. Although the use of the benzodiazepines can be recommended in therapeutic doses, it is not recommended to use benzodiazepines over a period of more than 2 - 3 weeks. Long term use makes anxiety worse and worsens the quality of sleep. Also, dependence can develop very quickly and some patients report withdrawal symptoms after only 4 weeks use at therapeutic (low) doses. The effects of long term usage include memory loss, aggressive behavior, mental confusion, depression, and loss of physical co-ordination. Although death from overdose is rare, the risks are very high if benzodiazepines are mixed with other 'downers' like barbiturates, opiates, or alcohol.
Works Cited Denning, P. , J. Little and A. Glickman. Over the influence: the harm reduction guide for managing drugs and alcohol.
The Guilford Press, 2003.
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Research essay sample on Central Nervous System Physical Dependence
