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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.
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Does the white rami communicans contain fibers of a preganglionic or postganglionic neurons?
Preganglionic because they are myelinated. FALSE
Does the gray rami communicans contain fibers of a preganglionic or postganglionic neurons?
could be preganglionic
What cranial nerves does not contain preganglionic parasympathetic fibers?
optic (II)
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.
Which nerves contain the most parasympathetic preganglionic fibers?
ciliary, pterygopalatine, otic, and submandibular.
What does white matter contain?
The white matter consist of myelinated nerve fibers.
Gray rami communicantes connect to what two structures?
White rami communicantes (sing. ramus communicans) are literally white branches of communication between each spinal nerve and the sympathetic trunk. Their color is white because these lines of communication contain mainly myelinated nerve fibers of pre-ganglionic general visceral efferents from the spinal cord. Many of the pre-ganglionic nerve fibers synapse at the corresponding spinal segment level, and thus build a sympathetic ganglion at that level. Other pre-ganglionic white fibers either ascend or descend in the sympathetic trunk before synapsing in sympathetic ganglia above or below the spinal segment of origin. The sympathetic ganglia are literally knots in the sympathetic cord primarily containing cell bodies of the post-ganglionic neurons, whose axons are unmyelinated and gray in color. These unmyelinated post-ganglionic nerve fibers rejoin the spinal nerve at that level via the gray rami communicantes,as well as ascending or descending to adjacent levels. The white rami may also contain lightly myelinated sympathetic afferents whose cell bodies in the dorsal root ganglia synapse in the dorsal horn gray of the spinal cord. ANSWER: Carry preganglionic axons to the sympathetic chain
What is white matter in the brain composed of?
largely or entirely composed of nerve fibers and contain few or no neuronal cell bodies or dendrites.
How many efferent neurons are used in a somatic action potential?
The autonomic reflex contains two. (preganglionic and postganglionic)
Are sweat glands parasympathetic or sympathetic?
They are sympathetic but an exception - ACh is released as a post-synaptic neurotransmitter rather than Adrenaline/Noradrenaline.Illicitinga parasympathetic response will not stimulate these neurons and therefore sweating is not a parasympathetic side effect.However, as post-synaptic sweat glands contain Muscarinic receptors and not adrenoceptors the administration of a non-selective Muscarinic agonist would result in both a parasympathetic response such as constriction of the pupil or decreased heart rate as well as sweating due to the activation of these sympathetic post-synaptic MAChR in the sweat glands.Atropine would reduce all parasympathetic responses and stop sweating.
Where are action potentials regenerated as they propagate along a myelinated axon?
First at the axon hillock where the neural impulse is initially triggered, and then at the nodes of Ranvier as the impulse continues to travel along the axon.(Note that the impulse travels as electrotonic conduction between the nodes of Ranvier, underneath the glial cells which myelinate the axon.)
Explain the 5-4-3 rule of networking?
A guideline for 10-Mbps Ethernet networks stating that between two communicating nodes, the network cannot contain more than five network segments connected by four repeating devices, and no more than three of the segments may be populated.
