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Which type of axon will velocity of action potential conduction be the fastest?
Wiki User
∙ 11y ago
Myelinated axons with the largest diameter
Wiki User
∙ 11y ago
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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).
What structure in the neuron helps to speed up the transmission of the action potential?
To speed up transmission of the action potential from where it originates (axon hillock) to where it ends (axon terminal), the action potential propagates by 'saltatory conduction' - and the structure that makes this possible is the insulating layer of myelin sheath that wraps around the axon, arranged in 'nodes' along its length. Technically, it's the gaps between the nodes (nodes of Ranvier) that cause the action to continually propagate and maintain its fast conduction velocity.
What is the node-to-node jumping regeneration of an action potential along a myelinated axon called?
saltatory conduction Saltatory conduction is derived from the Latin word saltare, which means leaping
Why myelin increase impulse conduction speed?
Propagation of an action potential down an axon has both a passive and an active component. The active component is the voltage activated opening of ion channels, but the passive so-called 'cable' properties of the axon also play a role. In a myelinated axon the ion channels are concentrated in the non-mylenated internodes. Current spreads with less loss of potential where there is mylein and this causes the action potential to leap from internode to internode. This is called saltory conduction.
In which direction does a nerve impulse usually move?
It's called the ACTION POTENTIAL, or, in the case of a myelinated axon, SALTATORY CONDUCTION.
Which of the following would have the fastest conduction of an action potential?
myelinated, large diameter fibres
The velocity of the action potential is fastest in which of the following axons?
a small myelinated axon
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).
What are the factors which affect the nerve conduction velocity?
The factors affecting nerve conduction velocity are as follows:(i) Axon diameter:An axon with a larger diameter conducts faster. In an unmyelinated fiber, the speed of propagation is directly proportional to the square root of the fiber diameter (D), i.e.,Conduction velocity a D(ii) Myelination and saltatory conduction:Myelination speeds up conduction. Thus, the action potential travels electrotonically along the long myelinated segments, and fresh action potentials are generated only at the nodes. This is called saltatory conduction. In a myelinated neuron, the conduction velocity is directly proportional to the fiber diameter (D).(iii) Temperature:A decrease in temperature slows down conduction velocity, (iv) Resting membrane potential. Effect of RMP changes on conduction velocity is quite variable. Usually, any change in the RMP in either direction (hyper polarization or depolarization) slows down the conduction velocity.
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.
Conduction along a myelinated axon is called?
It is called saltatory conduction. This describes the "jumping" of an action potential from node to node on a myelinated axon.
What is salutatory conduction?
Saltatory conduction refers to the propagation of action potentials along myelinated axons from one node of Ranvier to the next node. It increases the conduction velocity of action potentials.
What structure in the neuron helps to speed up the transmission of the action potential?
To speed up transmission of the action potential from where it originates (axon hillock) to where it ends (axon terminal), the action potential propagates by 'saltatory conduction' - and the structure that makes this possible is the insulating layer of myelin sheath that wraps around the axon, arranged in 'nodes' along its length. Technically, it's the gaps between the nodes (nodes of Ranvier) that cause the action to continually propagate and maintain its fast conduction velocity.
If the position of a nerve was reversed and its conduction velocity recorded would it be the same as if it were not reversed?
Nerve conduction is the same in both directions. The rate of conduction is mediated by the physical properties of the nerve and the voltage sensitive channels so as long as the diameter is constant the spread of the action potential would be the same in either direction.
What will increase the rate of conduction of an action potential along a nerve?
Myelinating the nerve
Is saltatory conduction made possible by large nerves fibers diphasic impulses myelin sheath or erratic transmission of nerve impulses?
Saltatory conduction is made possible by gaps in the myelin sheath (called nodes of Ranvier) along the axon, which allow for the action potential to "jump" from one node to the other, increasing conduction velocity.
Which nerve shortens the conduction time of an action potential through the AV node?
vagalstimulation
