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23 terms

Chapter 9~Nervous System

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action potential
sequence electrical changes when a nerve cell membrane is exposed to a stimulus that exceeds its threshold
autonomic nervous system
portion of nervous system that controls actions of viscera and skin
axon
nerve fiber that conducts nerve impulse away from neuron cell body
central nervous system (CNS)
portion of nervous system that consists of the brain and spinal cord
convergence
nerve impulses arriving at the same neuron
dendrite
nerve fiber that transmits impulses impulses toward neuron cell body
divergence
a neuron sending impulses to multiple other neurons
effector
muscle or gland that responds to stimulation
facilitation
subthreshold stimulation of a neuron that makes it more responsive to further stimulation
ganglion
mass of neuron cell bodies, usually outside central nervous system
meningers
three membranes that cover the brain and spinal cord
myelin
fatty material that forms sheathlike coverings around some nerve fibers
neurilemma
sheath formed from Schwann cells on outside of some nerve cells
neurotransmitter
chemical that axon ends secrets to control another neuron or an effector
nissl body
rough membraneous sacs aka: chromatophilic substance
parasympathetic nervous system
portion of autonomic nervous system that arises from brrain and sacral reigons of spinal cord
peripheral nervous system (PNS)
portions of nervous system outside central nervous system
plexus
network of interlaced nerves or blood vessels
reflex
rapid automatic response to a stimulus
sensory receptor
specialized structure associated with the peripheral end of a sensory neuron specific to detecting a particualr sensation and triggering a nerve impulse in response
somatic nervous system
motor pathways of peripheral nervous system that lead to skeletal muscles
sympathetic nervous system
portion of autonomic nervous system that arisees from thoracic and lumbar reigons of spinal cord
synapse
junction between axon of one neuron and dendrite or cell body of another neuron