The brain is the largest part of nervous system and contains 10billion -100billion nerve cells. All of the nerve cells are different sizes, shapes, functions they carry out and chemicals they produce. To understand the brain we need to look at the structure of the nervous system. The brain has 3 primary jobs: controlling behaviour, processing and storing information about the environment and adjusting the body\u2019s physiological processes. There are two divisions which make up the central nervous system: the spinal cord and the brain. The spinal cord is connected to the base of the brain and runs along the spinal column. The brain contains three major parts: The brain stem <\/em>\u2013 controls physiological functions and automatic behaviours The brain and spinal cord float in a liquid known as cerebrospinal fluid (CSF) that provides a cushion like protection. A blood brain barrier, ensures less substances pass from the blood to the brain to reduce toxic chemicals. A cerebral cortex, which is a 3mm layer of tissue, covers the surface of the cerebral hemisphere and has a billion nerve cells. The brain works with the body through the peripheral nervous system. Neurons communicate with cells through synapse. When a message is sent from the presynaptic neuron it is received by the postsynaptic. A neuron accept s messages for lots of terminal buttons which results in terminal buttons creating synapses with several all neurons. Communication between synapses is chemical producing called neurotransmitter. When the axon is fires an actions moves down an axon causing the terminal buttons to release the neurotransmitter chemical.<\/p>\n Drugs and Behaviour<\/strong><\/p>\n Chemicals that can be found in nature can affect people\u2019s perceptions and behaviours. But some of these chemicals can be useful and are used as therapeutic remedies. By understanding how drugs affect the brain, help us to understand disorders and how to develop new methods of treatment.<\/p>\n Drugs can be said to alter our thoughts, the way we perceive things, the emotions we have, and the behaviour we demonstrate. This is achieved by affecting the activity of the neurons in our brain. Some drugs can stimulate or inhibit the release of neurotransmitters (chemical that is realised when neurons communicate) when the axon is firing, e.g. the venom of a black widow spider. Some drugs can stimulate (e.g. nicotine) or block postsynaptic receptors (e.g. cocaine). Finally, some drugs can impede on the reuptake of the neurotransmitter after it has been released, e.g. botulinum toxin or block receptors all together e.g. curare. Glutamate <\/em>\u2013 has excitatory efforts, every sensory organ passes messages to the brain through axons with terminals that release glutamate. One type of glutamate receptor \u2013 NMDA can be affected by alcohol. This why some \u2018binge drinkers\u2019 sometimes say they have no memory of what happened the night before when they were drunk. Likewise if a person has been addicted to alcohol for a long time this receptor can become suppressed, making it more sensitive to glutamate. So if a person stops drinking alcohol then this can strongly disrupt the balance of excitation and inhibition in the brain.<\/p>\n GABA <\/em>\u2013 has inhibitory effects. Drugs that suppress behaviour, cause relaxation, sedation, and loss of consciousness act on a certain GABA receptor. For example if Barbiturates are taken in large quantities they can affect how a person walks, talking, cause unconsciousness, comas and even death.<\/p>\n Muscular movements are controlled by Acetylcholine (ACh) as well as controlling REM sleep (the part of sleep where most dreams occur), activation of neurons in the cerebral cortex and functions of the brain that are concerned with learning. ACh receptors are stimulated by the highly addicted drug nicotine. However the drug curare can block Ach receptors causing paralysis. Control of behaviour and the body\u2019s physiological functions<\/strong><\/p>\n <\/strong><\/p>\n
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\n The cerebellum<\/em> \u2013 controls and coordinates movements
\n The cerebral hemispheres <\/em>\u2013 concerned with perceptions, memories<\/p>\n
\nSensory information, decision making, and controlling muscles, are all sent to the brain through neurons which make up the nervous system. To receive, process, and transmit information neurons contain; dendrites, soma, axon, and terminal buttons. Support is provided by glia, that also produces chemicals required by neurons, remove chemicals not required and help protect neurons from infections.<\/p>\n
\nThere are two important neurotransmitters that help achieve synaptic communication:<\/p>\n
\nDopamine is important in helping movement and helps in reinforcing behaviours. People with Parkinson\u2019s disease are often given the drug L-DOPA to accelerate the production of dopamine. Drugs such as cocaine and amphetamine stop the uptake of dopamine and with people abusing these drugs would suggest that dopamine plays a role in enforcement.
\nNorepinephrine is said to increase vigilance and helps control REM sleep. Serotonin helps to control aggressive behaviour and risk taking, and drugs that have an impact on the uptake of serotonin are used to treat disorders concerned with anxiety, depression and obsessive compulsive disorders.<\/p>\n
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