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, biological psychologists people who engage in the scientific study of the links between biological and
psychological processes.
dendrites the bushy, branching extensions of a neuron that receive messages and conduct
impulses toward the cell body.
axon the neuron extension that passes and electrical messages through its branches to
other neurons or to muscles or glands.
myelin sheath a layer of fatty tissue segmentally encasing the fibers of many neurons; enables
vastly greater transmission speed of neural impulses as the impulse hops from one
node to the next.
action potential a neural impulse; a brief electrical charge that travels down an axon.
refractory period a period of inactivity after a neuron has fired.
threshold the level of stimulation required to trigger a neural impulse.
all-or-none principle a neuron's reaction of either firing or not firing.