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Canada (162,105)
Psychology (1,978)
PS268 (56)
Chapter 4

Drugs and Behaviour - Chapter 4

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Bruce Mc Kay

Drugs and Behaviour – Chapter 4  Components of the nervous system o Glia  10-50 times as many as neurons  Glia not only communicate with one another but also communicates with neurons and modulate their activity  Astrocytes supply glucose needed for nerve activity  Connected with one another via gap junctions  Network of interconnected astrocytes forms a network that behaves like a single entity  Plays major role in modulating neuronal activities  Creates blood-brain barrier, semipermeable  Protects brain from potentially toxic chemicals  Only small lipophilic molecules enter the brain  Extent to which chemicals can be dissolved in oils and fats  Heroin has more rapid onset of effects and more potent than morphine because it is more lipophilic o Neurons  Primary elements of nervous system responsible for analyzing and transmitting information  Everything dependent on the functioning of these cells  Contains more than 100 billion neurons  Cell body contains nucleus and other substances that sustain the neuron  Dendrites contain receptors  Axon responsible for conducting electrical signal to presynaptic terminals  Large doses of amphetamines can destroy axons and presynaptic terminals  Neurotransmission o Action potential  Essential process for neuronal communication is the action potential  Initiates chain of events that allow communications from one neuron to another  Polarized  When membrane potential is more negative  Hyperpolarized  Membrane potential is pushed below resting potential  Action potential occurs when membrane is depolarized  Depolarized o When membrane potential is less negative  Action potentials:  Not all or none  Do not travel undiminished in height from one end of axon to the other  Peripheral Nervous System o Made up of nerves outside brain and spinal cord o Consists of somatic and autonomic nervous system o Somatic nervous system  Nerve cells on front line  Peripheral nerves carry sensory information into central nervous system and carry motor information out  Includes vision, hearing, taste, smell, chewing and movements of tongue and face, information from skin and joints and movement of arms and legs  Neurotransmitter at neuromuscular junctions in somatic system is acetylcholine Drugs and Behaviour – Chapter 4  Neuromuscular junction - Synapse between a muscle and neuron  Acetylcholine – neurotransmitter found in parasympathetic branch in cerebral cortex o Autonomic nervous system  Body’s internal environment is monitored and controlled by autonomic nervous system  Chemical neurotransmission first studied here  Divided into sympathetic and parasympathetic branches  Sympathetic branch  Norepinephrine is the neurotransmitter at the end organ  Sympathetic system is interconnected  Acts as one unit  Those drugs that activate the sympathetic branch are referred to as sympathomimetic drugs o Central nervous system  Consists of brain and spinal cord  Most of integration of information, learning and memory and coordination of activity occurs  The brain o Major structures  Some areas of the cortex are known to be involved in processing visual information  Smaller cortical areas involved in control of muscles  Larger areas referred to as association areas  Basal ganglia underneath cerebral cortex on each side of brain  Subcortical brain structures controlling muscle tone o Important for maintenance of proper muscle tone  Too much output can cause rigidity and can occur during Parkinson’s disease  Hypothalamus  Small structure near base of the brain above pituitary gland  Important link between brain and hormonal output of pituitary and involved in feeding, drinking, temperature regulation and sexual behaviour o Chemical pathways  Dopamine  Cells in nucleus accumbens receives input from dopamine to form mesolimbic dopamine pathway o Nucleus accumbens – collection of neurons in forebrain o Mesolimbic dopamine pathway – one of two major dopamine pathways  Mediates some
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