Two Minutes of Anatomy: Myelin Sheath

Dr Donald A Ozello DC
Dr Donald A Ozello DC
11.2 هزار بار بازدید - 2 سال پیش - Myelin Sheath Most axons and
Myelin Sheath
Most axons and long dendrites are coated with a protective covering called myelin.
Myelin is a membrane that acts as an electrical insulator to increase the speed of conduction of impulses.
Myelin does not cover the neurite completely but leaves gaps called nodes of Ranvier.
In the central nervous system (CNS), myelin derives from glial cells called oligodendrocyte. Each oligodendrocyte forms multiple sheaths (up to 30 or more) around different axons
In the peripheral nervous system (PNS), the source of myelin is specialized cells called Schwann cells. Each Schwann cell creates a single myelin sheath around a single axon.
An axon wrapped in myelin sheath is said to be myelinated fibers, while axons not wrapped in myelin are called non-myelinated or demyelinated fibers.

Nerves
Primary function of nerves is to send information throughout the body via electrochemical signals.
Nerves classify into three functional categories: sensory neurons, motor neurons, and interneurons.
Sensory neurons receive and interpret sensory stimuli, motor neurons relay messages to muscles or glands, and interneurons transmit signals between other neurons.
Nerve fibers that send information from sensory neurons to the central nervous system are termed afferent nerve fibers, while nerve fibers that carry information away from the central nervous system, such as the motor neurons to the muscles, are termed efferent nerve fibers.
The sensory receptors are specialized regions or structures of the sensory neurons responsible for detecting senses and performing functions throughout the body. These receptors respond to changes in the environment by converting chemical or mechanical energy into action potentials to be transmitted towards the central nervous system.
Different types of stimulus receptors mediate each of the five basic human senses (sight, hearing, smell, taste, and touch). There are many other types of receptors, including chemoreceptors, photoreceptors, baroreceptors, and proprioceptors, which detect chemicals, light, pressure, and movement, respectively.

In the central nervous system, the myelinated fibers have the collective name of white matter, and the nonmyelinated fibers are collectively known as gray matter as they look white and gray respectively.

References
Physiology, Nerve
https://www.ncbi.nlm.nih.gov/books/NB...

Histology, Myelin
https://www.ncbi.nlm.nih.gov/books/NB...

Myelination
https://www.sciencedirect.com/science...

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Dr Donald A Ozello DC of Championship Chiropractic in Las Vegas, NV
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2 سال پیش در تاریخ 1401/04/07 منتشر شده است.
11,232 بـار بازدید شده
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