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what is expected to occur first if the membrane potential increase were to reach the threshold value?
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Membrane potential required to achieve threshold?
-55mV
A neuron fires only when its membrane reaches what?
When it reaches the nerve impulse threshold, the next neuron will fire..
When a stimulus is sufficiently great enough to change the membrane potential and propagate an action potential it is called?
recruitement
What does it take to trigger an action potential?
neurotransmitters from the presynaptic neuron must be released and binded to the ligand gated sodium channels to increase the membrane potential (increase the charge) until it reaches the threshold of the trigger zone which is -55 millivolts.
What is sub threshold Depolarization of nerves?
Subthreshold depolarization refers to a small increase in the membrane potential of a nerve cell that does not reach the threshold for generating an action potential. It is a graded response that occurs when the membrane potential of the nerve cell approaches but does not exceed the threshold for firing an action potential. Subthreshold depolarizations can summate or integrate within the cell to reach the threshold and trigger an action potential.
Membrane potential required to achieve threshold?
-55mV
A neuron fires only when its membrane reaches what?
When it reaches the nerve impulse threshold, the next neuron will fire..
When a stimulus is sufficiently great enough to change the membrane potential and propagate an action potential it is called?
recruitement
What does it take to trigger an action potential?
neurotransmitters from the presynaptic neuron must be released and binded to the ligand gated sodium channels to increase the membrane potential (increase the charge) until it reaches the threshold of the trigger zone which is -55 millivolts.
What is sub threshold Depolarization of nerves?
Subthreshold depolarization refers to a small increase in the membrane potential of a nerve cell that does not reach the threshold for generating an action potential. It is a graded response that occurs when the membrane potential of the nerve cell approaches but does not exceed the threshold for firing an action potential. Subthreshold depolarizations can summate or integrate within the cell to reach the threshold and trigger an action potential.
How are potential and action potential related?
Resting potential and action potential are both names for the measure of electrical voltage within the membrane of a cell. Specifically, these terms are used in describing the transfer of information along neural pathways. Resting potential is a state where cells are at rest. However, if an electrical response or depolarization reaches threshold, then ion channels open, allowing sodium ions to rush into the membrane and increase the voltage measure, firing an action potential along the length of this membrane.
What is a sub-threshold change in membrane potential within the cell body that decays as it travels away from its point of origin?
synaptic/graded potential
Which is greater - The extent of membrane polarization at threshold potential or that of the resting membrane potential?
A cell is more depolarized at it's threshold potential than it is at it's resting potential. This is important because a nervous system where a random excitatory post synaptic potential (epsp) would trigger the next neuron would lead to an overly excitable nervous system (btw, this is why caffeine makes you jittery).
What effect of the action potential if sodium channels are kept closed?
The action potential will not generate if the sodium channels are kept closed.This is because the sodium channels are responsible for the dramatic rising phase of membrane depolarization that occurs when the threshold of activation is reached. As a membrane potential gradually depolarizes (which can occur for a variety of reasons such as neurotransmitter stimulation, mechanical deformation of the membrane, etc), that membrane potential gradually comes closer to that threshold of activation. Once that threshold is reached, the voltage gated sodium channels open and allow for a dramatic influx of sodium ions into the cell. This results in a rapid depolarization which is seen as the rising phase of that upward spike noted in an action potential. Without the ability to open these sodium channels we may reach the threshold of activation, but the actual action potential will not occur.
Minimum level of stimulation required to trigger a neural impulse?
An action potential needs to occur to trigger the neurons but the action potential depends on whether a stimulus is able to bring the membrane potential to a certain level termed the THRESHOLD. This threshold is about -55 mV for most neurons, but the stimulus needs to bring the membrane potential to this certain level or it will not be triggered. Relating to the ALL-OR-NONE PRINCIPLE, which if the threshold is not acquired then an action potential will not occur but once a stimulus is strong enough to depolarize (making the inside of the cell less negative going from -70 mV to -55 mV) it will trigger. The resting potential is -70 mV which the stimulus needs to bring it up to -55mV.
Hyperkalemia have on the nervous system?
Hyperkalemia decrease a cell's membrane potential beyond the threshold value so it can't depolarize again.
How does novocain works on axon membrane?
It inhibits the action potential from reaching threshold. This is done by blocking the Na channels not allowing it to depolarize.
