Study Set Content:
Classic synapses such as the mammalian neuromuscular junction and most neuron-neuron synapses are relatively (blank) in that the nerve terminates in small boutons very close to the tissue innervated
"tight"
Classic synapses such as the mammalian neuromuscular junction and most neuron-neuron synapses are relatively "tight" in that the nerve terminates in small boutons very close to the tissue innervated, so that the diffusion path from nerve terminal to postsynaptic receptors is very
short
The effects are thus relatively
rapid and localized
In contrast, junctions between autonomic neuron terminals and effector cells (smooth muscle, cardiac muscle, glands) differ from classic synapses in that transmitter is often released from a (blank) in the postganglionic nerve fiber in the region of the smooth muscle cells rather than from boutons, and autonomic junctional clefts are wider than somatic synaptic clefts
chain of varicosities
Effects are thus (blank) in onset and discharge of a single motor fiber often activates or inhibits many effector cells
slower
For this synapse, a single neuron may contain thousands of synapses. In fact one type of neuron called the (blank) found the brain mainly the cerebellum may have as many as 100 000 of synapses
Purkinje cell
An important traditional classification of autonomic nerves is based on the primary transmitter molecules:
Acetylcholine
Norepinephrine
released from their terminal boutons and varicosities.
Norepinephrine-
they are cholinergic fibers; that is, they work by releasing
ACETYLCHOLINE
Almost all efferent fibers leaving the CNS are
cholinergic.
In addition, most parasympathetic postganglionic and a few sympathetic postganglionic fibers are
cholinergic
A significant number of parasympathetic postganglionic neurons utilize (blank)as the primary transmitter or cotransmitters.
nitric oxide or peptides
Most postganglionic sympathetic fibers release norepinephrine (also known as
noradrenaline
They are noradrenergic fibers (often called simply
adrenergic
They work by releasing They work by releasing
noradrenergic fibers
As noted, some sympathetic fibers release
acetylcholine
is a very important transmitter in the CNS, and there is evidence that it may be released by some peripheral sympathetic fibers.
Dopamine
which are embryologically analogous to postganglionic sympathetic neurons, release a mixture of epinephrine and norepinephrine.
Adrenal medullary cells
Five key features of neurotransmitter function provide potential targets for pharmacologic therapy:
synthesis, storage, release, and termination of action of the transmitter, and receptor effects.
WHAT ARE THE TWO PRINCIPAL NEUROTRANSMITTERS IN THE ANS???
Acetylcholine
Norepinephrine
