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epinepherine and norepinephrine
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∙ 12y ago
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What secretes norepinephrine adrenergic fibers?
sympathetic division. Parasympathetic division fibers called cholinergic fibers release acetylcholine.
A pelvic splanchnic nerve contains?
preganglionic parasympathetic fibers
Which nerves contain the most parasympathetic preganglionic fibers a trigeminal b splanchnic c optic d vagus?
D. vagus. this is the largest Cranial nerve, carrying parasympathetic information to much of the body (ie. esophagus, GI tract, heart). parasympathetic fibers, unlike sympathetic fibers, do not synapse until they are pretty much on in or near the organ. So the vagus is made up of preganglionic parasympathetics.trigeminal contains somatic afferents, and somatic efferents. neither of these are visceral efferents (which could be para or sympathetic).wikipedia tells you correctly that splanchnic nerves are generally sympathetic autonomics, except for one spot.optic nerve is carrying Afferent sensory information Away from the eye.
Why are sympathetic responses generally widespread?
Sympathetic responses are more widespread because of the way the efferent nerves (from spinal cord outward) are positioned. The autonomic system has two neurons between its spinal cord and the organ that it is modulating whereas the somatic system has only one. The difference between the sympathetic and the parasympathetic is that in the case of sympathetic, the first nerve out of the spinal cord, called the preganglionic fiber is extremely short and ends relatively close to the spinal cord. Here, the preganglionic fiber synapses with on average of 10 postganglionic fibers which then moves onto effect a variety of different organs. On the other hand, in the parasympathetic division the preganglionic nerve are extremely long and extends until it is almost at the organ. From there, it synapses with a very short post-synaptic nerve that then synapses an organ. The ratio in this case can be about 1:3 but usually is 1:1. To sum things up, in the sympathetic division, the preganglionic fiber terminates very early and therefore has the "opportunity" to interact with a variety of nerves. On the other hand, the parasympathetic division has such a long preganglionic fiber that by the time it synapses its post ganglionic fiber, it is pretty much at the organ. NE and epinephrine are secreted into the blood as part of the sympathetic response.
What fibers are the sweat glands innervated by?
sympathetic
What fibers are located in the white rami?
Sympathetic preganglionic.
Do the sympathetic fibers leave the CNS at the thoracolumbar region?
All preganglionic sympathetic fibers leave the CNS at the thoracolumbar region, yes.
Which division of the autonomic nervous system is characterized by short preganglionic and long postganglionic fibers?
The parasympathetic nervous system has long preganglionic and short postganglionic fibers
Does the white rami communicans contain fibers of a preganglionic or postganglionic neurons?
Preganglionic because they are myelinated. FALSE
How would a drug that stimulates acetylcholine receptors affect the sympathetic nervous system?
Preganglionic fibers for the SNS release ACh; so a drug that stimulates ACh receptors would stimulate the postganglionic fibers of sypathetic nerves, resulting in increased sympathetic activity
What stimulates the adrenal medulla to secrete its excitatory hormones?
preganglionic sympathetic fibers releasing acetylcholine that bind to receptors on the adrenal medulla
Do the white communicating rami contain myelinated preganglionic sympathetic nerve fibers and are present in all apinal nerves?
Yes and No. White communicating rami contain mylinated preganglionic sympathetic nerve fibers, but are only present at the levels of spinal cord segments T1-L2 (where the cell bodies for these nerve fibers exist in the lateral horn of the spinal cord). Although the sympathetic fibers only arise in the T1-L2 spinal cord segments, they are dispersed to all spinal nerves by traveling through the sympathetic chain. The preganglionic sympathetic fibers will enter the sympathetic chain thru whit rami communicans and then do one of 4 things: 1. synapse with a postganglionic cell body in the sympathetic chain at the level it enters 2. ascend within the chain to synapse 3. descend within the chain to synapse 4. splanchnic nerves leave the chain without synapsing and synapse closer to the organ they innervate.There are, however, GRAY rami communicans for all spinal nerves.I hope that helps
Does the gray rami communicans contain fibers of a preganglionic or postganglionic neurons?
could be preganglionic
What secretes norepinephrine adrenergic fibers?
sympathetic division. Parasympathetic division fibers called cholinergic fibers release acetylcholine.
A pelvic splanchnic nerve contains?
preganglionic parasympathetic fibers
Are preganglionic neurons made up of adrenergic fibers?
yes
Are nerve fibers in ascending tracts myelinated?
If I was paying attention in med school, I think... The pre-ganglionic fibers are myelinated and the post-ganglionic are unmyelinated. This is in reference to the sympathetic and parasympathetic systems.
