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Nerve conduction velocity studies (NCV) are used to measure the speed with which an electrical signal is transferred along the nerve.
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What is a Nerve conduction velocity test?
A test that measures the time it takes a nerve impulse to travel a specific distance over the nerve after electronic stimulation.
How does temperature on a physiological way effect nerve conduction?
Myelination will speed the nerve conduction velocity considerably. Myelin is found in Schwann cells which encircle a given axon. It acts mainly as an insulator so that depolarization in one cell does not set off depolarizations in adjoining cells. When a neural membrane is depolarized, local currents are set up between positive and negative ions causing membrane conduction. In myelinated fibers, the local currents go from one internode (or node of Ranvier) in between two Schwann cells to the next internode. Thus we have "salutatory conduction" where a neural impulse actually jumps from one internode to the next without being conducted down the entire cell membrane.
What does a conduction velocity of an action potential depend on?
An action potential does not have a conduction velocity. Rather, it makes sense to measure the conduction velocity of nerves or nerve cells and this is usually done in metres per second (m/s.). An action potential is characterised as "an all or none response". This means you cannot alter the characteristics of an action potential in a given nerve cell. If you get a nerve cell and manage to get it to threshold, produce and measure an action potential 1000 times or more at the exact same point on the cell, the action potential you measure will not change in timing or amplitude. Information travels down a nerve cell through action potentials. But it is not one action potential that travels the whole length of the axon. Instead what happens is that one action potential causes the next bit of the nerve cell to reach threshold and therefore creates an entirely new action potential. So you actually need multiple action potentials to happen along a nerve cell to send information down it. We call this "propagation of action potentials" since each action potential produces a new one. More properly, it is referred to as "saltatory action potential conduction". Conduction velocity is basically a measure of how quickly we can produce a series of action potentials to travel the distance of the nerve cell axon. Since action potentials only happen at each "Node of Ranvier", then the longer the distance between each node (internodal distance), the faster the conduction velocity of a nerve cell. Since the internodal distance is positively correlated with myelin thickness, more thickly myelinated nerve cells have faster conduction velocities. The thickest and fastest nerve cells are motor neurones and Ia fibres from muscle spindles with a diameter of 12-20 micrometres and a conduction velocity of 70-120 m/s. The thinnest/slowest are fibres used to convey slow pain (<1.5 micrometres and 0.5-2 m/s).
Conduction of nerve impulses is possible because of the?
Conduction of nerve impulses is possible because ions in the extracellular environment versus the ions inside the cell.
What is electrotonic conduction of a nerve?
is a test commonly used to evaluate function
What is nerve conduction velocity test?
Nerve conduction velocity test-- A test that measures the time it takes a nerve impulse to travel a specific distance over the nerve after electronic stimulation.
Who invented the nerve conduction velocity test?
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What is the nerve conduction velocity test?
It measures the ability of the nerve to conduct electrical signals
What is the relationship between nerve size and conduction velocity?
velocity proportional to square root of diameter
What is the relationship between size of nerve and conduction velocity?
For unmyelinated nerves there is a relationship between axon diameter and conduction velocity. Larger diameter nerves conduct faster. For myelinated nerves the a larger diameter nerve will conduct faster between the nodes of ranvier where the action potential is propagated. Conduction is said to be saltatoryas it jumps from node to node.
Is the velocity of a nerve impulse greater than electrical conduction's?
yes
What is NCV?
A person that is certified to perform nerve conduction studies
Is a elctroneuromyography also known as nerve conduction studies?
False
What is ncv technician?
A person that is certified to perform nerve conduction studies
The velocity of nerve impulse conduction is greatest in?
Heavily myelinated, large diameter fibers
What does the medical abbreviation NCS mean?
Nasal Cannula
What is a Nerve conduction velocity test?
A test that measures the time it takes a nerve impulse to travel a specific distance over the nerve after electronic stimulation.
