Myelin Sheath

Created by

Amber Foster

Cards (40)

If you wanted to observe the detailed structure of the myelin sheath, which microscope would you use?
Electron microscope
What does the image in the study material illustrate about myelination?
It shows the wrapping process of Schwann cells
What are the gaps in the myelin sheath called?
Nodes of Ranvier
What are the specialized cells that form myelin in the central nervous system?
Oligodendrocytes
What is the role of the myelin sheath in myelinated axons?
The myelin sheath acts as an insulator, allowing for saltatory conduction and faster transmission of signals
What is the name of the specialized structure that allows for saltatory conduction in myelinated axons?
Node of Ranvier
What do Schwann cells create during myelination?
The myelin sheath around the axon
What are the benefits of myelination in neurons?
Increases speed of impulse transmission
Reduces energy consumption for the neuron
Enhances overall efficiency of neural communication
What are the key functions and characteristics of the myelin sheath?
Fatty layer around axons
Speeds up nerve signal transmission
Formed by Schwann cells (PNS) and oligodendrocytes (CNS)
Contains gaps called nodes of Ranvier
Nodes maintain fast signal propagation
How does the transmission speed in myelinated neurons compare to unmyelinated neurons?
Myelinated neurons transmit impulses faster
What are the specialized support cells that wrap myelin layers in the central nervous system?
Oligodendrocytes
How often do nodes of Ranvier occur along the axon?
Every 1-2 mm
What does the image in the study material illustrate about myelinated axons?
(a) Simplified diagram of myelinated axon
(b) Cross-section showing concentric myelin layers
(c) Light microscopy view of many myelinated axons
(d) Electron microscopy view of myelin layers
(e) Fluorescent microscopy showing myelin distribution
What are the steps in the myelination process by Schwann cells?
Schwann cell covers the axon
Schwann cell wraps around in spirals
Multiple layers accumulate to form myelin
The process leaves a space for the Node of Ranvier
Why does the voltage decay faster in myelinated axons compared to non-myelinated axons?
Due to the presence of voltage-gated ion channels at the nodes of Ranvier
What are nodes of Ranvier?
Unmyelinated gaps in the myelin sheath
How does the myelin sheath affect nerve signal transmission?
It speeds up the transmission of nerve signals
What is the function of the myelin sheath?
It allows for saltatory conduction
What is the role of the myelin sheath in neuron function?
It speeds up electrical impulse transmission
What happens to the Schwann cell nucleus during myelination?
It moves to the side of the cell
How does the myelin sheath facilitate faster transmission of impulses?
Through saltatory conduction along axons
What is the difference between myelinated and non-myelinated axons in terms of conduction speed?
Myelinated axons have fast conduction speed (Fast)
Non-myelinated axons have slow conduction speed (Slow)
What are the specialized cells that form myelin in the peripheral nervous system?
Schwann cells
How does the voltage-gated ion channel mechanism work in myelinated axons?
Voltage-gated ion channels are present in the bare plasma membrane (nodes of Ranvier)
This allows for rapid depolarization and repolarization, resulting in faster conduction speed
How do Schwann cells contribute to the myelination process?
They wrap around the axon in multiple layers
What is saltatory conduction in neurons?
Transmission of impulses along myelinated axons
Impulses jump between nodes of Ranvier
Results in faster transmission than unmyelinated neurons
How does the voltage decay differ between myelinated and non-myelinated axons?
In myelinated axons, the voltage decays rapidly (Voltage-gated ion channels)
In non-myelinated axons, the voltage decays slowly (Slow conduction)
What is wrapped around the axon?
Myelin layers
What is the significance of the layers added by Schwann cells during myelination?
They form the myelin sheath for insulation
How do the mechanisms of conduction in myelinated and non-myelinated axons differ?
Myelinated axons use saltatory conduction via voltage-gated ion channels, while non-myelinated axons use continuous conduction
How does the speed of saltatory conduction compare to non-myelinated transmission?
It is much faster than non-myelinated transmission
What are the specialized support cells that wrap myelin layers in the peripheral nervous system?
Schwann cells
What is the primary function of the myelin sheath in myelinated axons?
To insulate the axon and allow for faster conduction of electrical signals
How does saltatory conduction work?
Electrical impulses jump between nodes of Ranvier
What is the process of myelination?
Wrapping of Schwann cells around an axon
What is the myelin sheath?
A fatty layer around some axons
What are the key features of saltatory conduction?
Impulses jump between nodes of Ranvier
Significantly faster than non-myelinated transmission
Prevents signal loss
What is the significance of the nodes of Ranvier?
They help maintain fast signal propagation
What is left at the end of the myelination process?
A space for the Node of Ranvier
What role does myelin play in signal loss?
Myelin prevents signal loss during transmission