34

if a nerve fiber responds at all to a stimulus, it responds completely by conducting an impulse

____ triggers more impulses per second, not stronger impulses

nerve impulses travel from neuron to neuron along complex

the junction between two communicating neurons is called a

between synapse across which the impulse must be conveyed

the process by which the impulse in the presynaptic neuron is transmitted across the synaptic cleft to the postsynaptic neuron is called

when an impulse reaches the synaptic knobs of an axon, synaptic vesicles release a _ into the synaptic cleft

reacts with specific receptors on the postsynaptic membrane

neurotransmitters that increase postsynaptic membrane permeability to sodium ions may trigger impulses and are thus

other neurotransmitters may decrease membrane permeability to sodium ions, reducing the chance that it will reach threshold, and are thus

at least _ kinds of neurotransmitters are produced by the nervous system, most of which are synthesized in the cytoplasm of the synaptic knobs and stored in synaptic vesicles

When an action potential reaches the synaptic knob, __ rush inward and, in response, some synaptic vesicles fuse with the membrane and release their contents to the synaptic cleft.

____ in synaptic clefts and on postsynaptic membranes rapidly decompose the neurotransmitters after their release

prevents continuous stimulation of the postsynaptic neuron.

Neurons within the CNS are organized into __ with varying numbers of cells.

A particular neuron of a pool may receive excitatory or inhibitory stimulation; if the net effect is excitatory but subthreshold, the neuron becomes more excitable to incoming stimulation

A single neuron within a pool may receive impulses from two or more fibers, which makes it possible for the neuron to summate impulses from different sources

Impulses leaving a neuron in a pool may be passed into several output fibers, a pattern that serves to amplify an impulse.