DREXEL PSY 310 - Ch 4 The Nervous System (6 pages)

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Ch 4 The Nervous System



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Ch 4 The Nervous System

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Pages:
6
School:
Drexel University
Course:
Psy 310 - Drugs & Human Behavior

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The Nervous System Homeostasis Humans maintain their internal environment within certain limits Examples body temperature water content glucose concentrations etc Psychoactive drugs influence homeostasis Alcohol inhibits vasopressin release antidiuretic hormone Thus after a drink more urine is produced Compared to light drinkers heavy drinkers produce less urine after a drink During alcohol withdrawal heavy drinkers exhibit increased vasopressin release Components of the Nervous System Two major types of cells in the nervous system Neurons or nerve cells Glia or glial cells Neurons Major function primary elements of the nervous system that analyze and transmit information Four defined regions Cell body Contains the nucleus and other sustaining substances Dendrites Contains receptors which respond to chemical signals Psychoactive drugs activate or inhibit neuron based on type of receptor Axon Conducts the action potential Axon terminals Contains synaptic vesicles which store neurotransmitters Neuron Schematic Glia Major functions Provide firmness and structure to the brain Get nutrients into the system Eliminate waste Form myelin Communicate with other glia neurons Glia also create the blood brain barrier Protects the brain from toxic chemicals Psychoactive drug molecules must be able to pass the barrier Neurotransmission Action potential a brief electrical signal transmitted along the axon Brief chain of events 1 Resting potential is caused by uneven distribution of ions o The neuron is hyperpolarized 2 Ion channels open allowing electrically charged particles to move inside the cell o As a result the neuron may become depolarized o all or none action potential occurs o Note Blocking ion channels prevents the action potential and disrupts neuronal communication 3 Neurotransmitters are released The Nervous System s Somatic nervous system Autonomic nervous system ANS Central nervous system CNS Sensory information into the CNS Motor information back out Voluntary



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