Group B nerve fibers are
axon
An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...
s, which are moderately
myelinated
Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be l ...
, which means less myelinated than
group A nerve fiber
Group A nerve fibers are one of the three classes of nerve fiber as ''generally classified'' by Erlanger and Gasser. The other two classes are the group B nerve fibers, and the group C nerve fibers. Group A are heavily myelinated, group B are ...
s, and more myelinated than
group C nerve fiber
Group C nerve fibers are one of three classes of nerve fiber in the central nervous system (CNS) and peripheral nervous system (PNS). The C group fibers are unmyelinated and have a small diameter and low conduction velocity, whereas Groups A ...
s. Their conduction velocity is 3 to 14
m/s. They are usually
general visceral afferent fibers
A general officer is an officer of high rank in the armies, and in some nations' air forces, space forces, and marines or naval infantry.
In some usages the term "general officer" refers to a rank above colonel."general, adj. and n.". OED O ...
and
preganglionic nerve fibers
In the autonomic nervous system, fibers from the CNS to the ganglion are known as preganglionic fibers. All preganglionic fibers, whether they are in the sympathetic division or in the parasympathetic division, are cholinergic (that is, these ...
of the
autonomic nervous system
The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies viscera, internal organs, smooth muscle and glands. The autonomic nervous system is a control ...
. They are used in Bainbridge reflex as afferents.
Neurohistology
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