Table of Contents
What types of neurons are myelinated?
Myelinated axons are present in sensory neurons and motor neurons. But all the motor neurons are not myelinated. Some are unmyelinated as well. Motor neurons of the somatic nervous system are myelinated and the motor neurons of the upper motor neurons are myelinated.
Where are myelinated axons found?
Most of the myelinated axons are found in the peripheral nervous system, while axons within the CNS are unmyelinated.
What is a myelinated axon?
A myelinated axon is one which is surrounded by a myelin sheath, comprised of Schwann cells. It is electrically insulating, except for gaps in the sheath which are called the Nodes of Ranvier. Due to the gaps in the myelin sheath, action potentials propagate by saltatory conduction.
Which axons are not myelinated?
Peripheral nerves This composite structure of the axon and a sheath of Schwann cells is the nerve fibre. The axons range in diameter from <1 to 20μm. The smallest axons, surrounded by columns of Schwann cell processes, are the non-myelinated nerve fibres and are the most common.
Are cranial nerves myelinated?
All the cranial nerves, except the optic and olfactory nerves, which are considered to be more a direct expansion of the central nervous system, have a transitional zone between central myelin (coming from oligodendrocytes) and peripheral myelin (produced by Schwann cells).
Where are there Unmyelinated neurons?
Compared to myelinated neurons, unmyelinated neurons are slower in terms of conducting impulses and are found in the peripheral nervous system (especially visceral nervous system) and the gray matter of the nervous system.
Which neuron is Unmyelinated?
A neuron in which there is no myelin sheath surrounding the axon. The unmyelinated neuron pertains to any of the neurons without myelin sheath (a sheath for the rapid conduction of action potential).
What nerves are not myelinated?
As the name suggests the non myelinated neurons are those whose axons are surrounded by the Schwann cells but they do not form the myelin sheath. These type of nerve fibers are found in parasympathetic and sympathetic nervous system.
What is the metabolic center of a neuron?
The cell body, also called the soma, is the metabolic center of the neuron. The nucleus is located in the cell body and most of the cell s protein synthesis occurs in the cell body.
What is the basic structure of a neuron?
The Structure of a Neuron. There are three basic parts of a neuron: the dendrites, the cell body, and the axon. However, all neurons vary somewhat in size, shape, and characteristics depending on the function and role of the neuron.