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Cards In This Set
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The nervous system has 2 types of specialized cells:
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1. neurons (nerve cells)2. neuroglial cells
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Neuroglial cells outnumber neurons, they provide what 3 things :
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1. structural support for neurons2. supply never growth factors3. form myelin sheaths around certain axons
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What are the 3 general categories for neurons.
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1. Sensory (or afferent) which conduct info from sensory receptors to CNS.2. Motor (or efferent) neurons which conduct info away from CNS to an effector (muscle or gland).3. Association (interneurons) which are positioned btwn sensory and motor neurons and are located in the CNS.
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Many branching fiber called ____________ conduct messages toward the cell body.
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Dendrites
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A single long _______ conducts impulses away from the cell body.
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Axon
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An axon may be enclosed in an insulating layer called a __________ ________.
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Myelin sheath
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The _______ ______ greatly increases the rate at which impulses are conducted along an axon, and also play a role in the regeneration of cut axons in the peripheral nervous system.
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Myelin sheath
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The message conducted by a neuron are called ______ ______ or action potential are caused by ______ ______ and _______ ______.
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nerve impulses and are caused by sodium ions and potassium ions
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Why is the resting potential important?
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(in the resting stage the inside surface is kept more negative than the outside surface)- which allows the neuron to respond more quickly than it could if the membrane were electrically neutral. EXP: (keeping car battery charged so it will start soon as you turn the key)
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What is Action Potential?
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When a neuron is stimulated, (receives some kind of signal) there is a sudden reversal in the charge difference across the membrane, followed by restoration period.
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Immediately after an action potential occurs, the neuron cannot be stimulated again for a brief instant called the ___________.
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Refractory period
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What happens to a sodium ions at the beginning of an action potential?
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Stimulus causes gates on sodium channels to open, sodium ions than enter neuron, their positive charge starts to reduce the negative charge within.
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What are neurotransmitters?
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A chemical released from the axon's tip, which diffuses across the gap and conveys the message to adjacent cell.
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How is the action of a neurotransmitter terminated? (2 ways)
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1. enzymes can deactivate them2. neurotransmitters may be actively pumped back into the presynaptic knobf
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Synapse?
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The junction between a neuron and another cell
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