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According to McGraw Hill (please see related link below):
Many nerve fibers in the CNS and PNS are unmyelinated. In the PNS, however, even the unmyelinated fibers are enveloped in Schwann cells. In this case, one Schwann cell harbors from 1 -12 small nerve fibers in grooves in its surface. The Schwann cell's plasma membrane does not spiral repeatedly around the fiber as it does in a myelin sheath, but folds once around each fiber and somewhat overlaps itself along the edges. This wrapping is the neurilemma (also called a mesaxon in unmyelinated nerve fibers). Also, gray matter of the brain and dendrites are unmyelinated, while axons are myelinated.
What else can I help you with?
Are dendrites always myelinated?
No, dendrites are typically unmyelinated. Myelin is a protective covering that surrounds axons to increase the speed of electrical impulse transmission. Dendrites receive signals from other neurons and transmit them towards the cell body.
The speed of nerve impulse transmission through the axon of a sensory neuron will be quickest in?
I'm guessing; "myelinated nerve fibres" contrary to the much slower "non-myelinated nerve fibres"
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.
Why node of ranvier is present on myelinated axon?
Nodes of ranvier are locations of bare cell membrane between segments of myelinated cell membrane. Ion channels responsible for repropagation of action potentials are concentrated at these nodes. Unmyelinated axons have ion channels all over their cell membranes since they do not have myelin segments.
What does non myelinated fibers look like?
Non-myelinated fibers appear as thin, unmyelinated axons within bundles of nerve fibers. They lack the myelin sheath that surrounds some other nerve fibers, which gives them a more transparent or grayish appearance compared to myelinated fibers. Non-myelinated fibers are typically smaller in diameter and conduct nerve impulses more slowly than myelinated fibers.
Does a worm have a myelinated or non-myelinated neuron?
non-myelinated
What is the neurilemma and what is it function?
the plasma membrane surrounding a Schwann cell of a myelinated nerve fiber and separating layers of myelin
Gray matter in the spinal cord is mostly?
unmyelinated axons.
What is the output structure of a neuron?
The axon is the output structure of a nerve cell. Many times it is myelinated like an electrical wire.
Are dendrites always myelinated?
No, dendrites are typically unmyelinated. Myelin is a protective covering that surrounds axons to increase the speed of electrical impulse transmission. Dendrites receive signals from other neurons and transmit them towards the cell body.
How is nerve impulse conducted along a myelinated nerve fiber?
In non-myelinated axons, the nerve impulse is going to be produced when the action potential accross a membrane makes a wave of depolarization followed by a wave of repolarization. With the absence of the myelin, the impulse is transmitted continuously throughout the membrane. In a non-myelinated nerve, once an end of the cell, the dendrite, is depolarized, the depolarization a.k.a., the action potential, moves along the nerve membrane, and the area of membrane immediately behind the depolarized section becomes repolarized.
The speed of nerve impulse transmission through the axon of a sensory neuron will be quickest in?
I'm guessing; "myelinated nerve fibres" contrary to the much slower "non-myelinated nerve fibres"
Myelinated neurons are embedded in what?
the axons of myelinated neurons are embeded in a protective covering of gray matter.
Are muscles and glands myelinated?
Muscles and glands are not myelinated. It is the axon of a neuron that is myelinated. The myelin forms a layer called myelin sheath that makes the nervous system function properly.
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.
Along myelinated sections between nodes in a myelinated axon electrical signals are conducted by?
Saltatory conduction is the process by which electrical signals jump between the nodes of Ranvier along myelinated axons, allowing for rapid transmission of action potentials. This occurs because the myelin sheath insulates the axon, forcing the electrical signal to "leap" from node to node where the membrane is exposed.
What spinal cord location would you find the origin of the white rami communicantes.?
The white rami communicantes are myelinated pre-ganglionic fibers (myelinated axons) from cell bodies located in the internal gray of the spinal cord. These fibers represent general visceral efferents of the sympathetic nervous system.
