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1Chapter 10 Key Terms
AcetylcholineEpinephrineAfferent NeuronsEfferent NeuronsAstrocytesAxonAxon TerminalsDopamineDendritesEndorphinsNeuronsReflex ArcSchwann CellsSynapseSerotoninGray MatterHorns
Dura Mater
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Nervous System
Control system of the bodyControls organs and systems of the body Interprets stimuli from environmentHelps us react to those stimuliHelps maintain homeostasis
4Nervous System
CNSBrain
Spinal Cord
PNSCranial nervesSpinal nerves
Afferent Efferent
Somatic Autonomic
Sympathetic Parasympathetic
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Organization
Central Nervous System (CNS)Controls the whole system Includes brain and spinal cord
Peripheral Nervous System (PNS)Consists of all nerves that connect the CNS with
sensory receptors, muscles, and glandsDivided into two categories
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Organization
PNSAfferent Peripheral System
Take info from sensory receptors to CNS
Efferent Peripheral SystemTake info from CNS to muscles and glands
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Organization
EfferentAutonomic Nervous System (ANS)
Impulses from CNS to smooth muscle, cardiac muscle, and glands
Involuntary
Somatic Nervous System (SNS)Impulses from CNS to skeletal muscleVoluntary
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Organization
ANSSympathetic division
Speeds up activity“Fight or flight” responseUses norepinephrine as neurotransmitter
Parasympathetic“Rest and digest” responseStimulates vegetative activities (digestion…)Uses acetylcholine as neurotransmitter
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Classification of Nerve Cells
Nervous tissue is a composition of 2 types of cellsNeuroglia (glial cells) – “nerve glue”
Support and protect neuronsMake up 60% of all brain cells
NeuronsNerve cells that transmit nerve impulses through
electrochemical changes
NervesBundle of nerve cells or fibers
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Classification of Nerve Cells
NeurogliaAstrocyte: attach nerve cell to blood vessel for
nutrientsOligodendoglia: support between nerve cellsMicroglial: protect CNS by destroying microbesEpendymal: line fluid-filled cavities of brainSchwann: form myelin sheath around nerve fibers in
PNS
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Structural Classification
MultipolarContains several dendrites and one axon
BipolarOne dendrite and one axonTwo processes come off the cell
UnipolarOnly one process from the bodyMost sensory neurons
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Functional Classification
Sensory Neuron (Afferent)Receive impulse directly from receptorUnipolar neurons
Association NeuronTransmit impulse to appropriate part of brain for processingMultipolar neurons found in brain and spinal cord (most
common) Motor Neuron (Efferent)
Final cell to receive impulse – causes reaction to the stimulus
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Nerve Impulse
Neuron contains concentrations of ions inside and outside of cellGreater concentration of Na+ ions outside of cellGreater concentration of K+ ions inside cellConcentration maintained by sodium-potassium pump
Resting PotentialPositive charge outside cell, negative charge inside
cell
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Nerve Impulse
Depolarization (Action Potential)Na+ rush into cell, causing positive charge inside cellAs this happens, K+ move outside to restore resting
potential Repolarization
Sodium-Potassium pump restores equilibriumPumps sodium back outside cell membrane and
potassium back inside cell membrane Transmission occurs only at nodes of Ranvier
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Nerve Impulse
All-or-None Law If a nerve fiber carries any
impulse, it will carry a full strength impulse
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Synaptic Transmission
SynapseArea where axon terminals
are anchored close to dendrites of another neuron
Neurotransmitters connect to receptors on postsynaptic neuron
This triggers an influx of sodium in postsynaptic neuron
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Synaptic Transmission
Acetylcholine is the most common neurotransmitter Acetylcholinesterase breaks down Acetylcholine
after it has performed its function Other notable neurotransmitters:
SerotoninEpinephrineDopamineEndorphins
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Reflexes
Involuntary reaction to an external stimulus Reflex Arc
Pathway that results in a reflex5 parts
Sensory receptor in skinAfferent/Sensory neuronAssociation neuron in spinal cordEfferent/Motor neuronEffector (Muscle)
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Common Reflexes
Knee-jerk reflex Blushing Cough reflex Shivering Yawning Babinski Reflex (Video) Eye-blink reflex
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Spinal Cord
Begins as continuation of the brain stem
Surrounded and protected by vertebrae (bone) and intervertebral disks (fibrocartilage)
Made up of 31 segments Also protected by a series of
connective tissue membranes called spinal meninges
Also protected by cerebrospinal fluid
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Spinal Cord
FunctionsTransmit impulses to and from the brainAlso is center for reflexes
Posterior/Dorsal RootContains only sensory fibers
Anterior/Ventral RootContains only motor fibers