Mod 9 Flashcards
Neuron
a nerve cell; the basic building block of the nervous system
Cell body
The part of the neuron that contains the nucleus, the cell’s life-support center.
Dendrites
a neuron’s bushy, branching extensions that receive messages and conduct impulses toward the cell body
Axon
the neuron extension that passes messages through its branches to other neurons or to muscles or glands
myelin sheath
a fatty tissue layer segmentally encasing the axons of some neurons; increases transmission speed and provides insulation.
glial cells
cells in the nervous system that support, nourish, and protect neurons; they also play a role in learning, thinking, and memory.
action potential
a neural impulse; a brief electrical charge that travels down an axon
Threshold
the level of stimulation required to trigger a neural impulse
All-or-none response
a neuron’s reaction of either firing or not firing
Excitatory signals
neurotransmitter signals that trigger action
Inhibitory signals
neurotransmitter signals that depress action
Synapse
The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
Refractory period
a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state
Neurotransmitters
chemical messengers that travel across the synapse and bind to receptor sites on the receiving neuron
Reuptake
a neurotransmitter’s reabsorption by the sending neuron
