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A neuron in its resting state, or resting potential, is not conducting an action potential, so its outside it is positive. It is only when it is conducting an action potential that it becomes depolarized and changes so its outside is negatively charged.
The interior of a neuron's axon is negatively charged due to the presence of proteins and chloride ions both bearing negative charges. The chloride ions ions are able to pass through the cell membrane, although I do not recall if that movement is exclusively through voltage-gated channels.
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Does a neuron become more negative during a nerve impulse?
No. The inside of the neuron becomes more positively charged. The resting potential is -70 millivolts. So, the outside of the neuron starts off being more positively-charged, and the inside is more negatively-charged. As sodium ions (which are cations - positively-charged ions) move into the neuron (via sodium ion channels), this depolarizes the neuron (induces a "signal"). If this net signal is above a certain threshold, it will trigger an action potential, whereby channels will open in the axon, just ahead of the action potential itself, which allows more cations to flow into the axon, increasing the positive charge inside the axon, and further triggering the opening of cation channels downstream. Note: As the action potential (positively-charged region inside an axon) propagates down the axon, sodium channels open behind it to pump sodium ions back outside the axon, restoring the inner negative charge of that region, so that it can return to the resting potential. Therefore, once the action potential is formed inside the axon, and is moving downstream, sodium pumps open behind it so that the signal is dampened in an already-activated region, thereby restoring the resting potential. This prevents retriggering a secondary action potential (which would result in amplification of the end signal). On the other hand, when an inhibitory neurotransmitter binds with the neuron, or else a chloride ion channel (chloride ions are anionic - negatively-charged) opens, chloride ions enter the neuron, which drives the membrane potential further into the negative, thereby reducing the likelihood of action potential (signal) generation.
When an axon is not conducting an impulse is known as?
Resting Potential
What are the electrically charged molecules involved in nerve impulses called?
axon
What occurs in repolarization?
As the axon repolarizes Na+ channels open to bring the cell from a resting state -70mv to -55mv and grater (grater being -55mv through 0mv).
What happens when a neuron becomes excitable?
A neuron which is excitable is in its RESTING STATE, which means that it is POLARIZED, and thus able to be stimulated into an action potential.
Does a neuron become more negative during a nerve impulse?
No. The inside of the neuron becomes more positively charged. The resting potential is -70 millivolts. So, the outside of the neuron starts off being more positively-charged, and the inside is more negatively-charged. As sodium ions (which are cations - positively-charged ions) move into the neuron (via sodium ion channels), this depolarizes the neuron (induces a "signal"). If this net signal is above a certain threshold, it will trigger an action potential, whereby channels will open in the axon, just ahead of the action potential itself, which allows more cations to flow into the axon, increasing the positive charge inside the axon, and further triggering the opening of cation channels downstream. Note: As the action potential (positively-charged region inside an axon) propagates down the axon, sodium channels open behind it to pump sodium ions back outside the axon, restoring the inner negative charge of that region, so that it can return to the resting potential. Therefore, once the action potential is formed inside the axon, and is moving downstream, sodium pumps open behind it so that the signal is dampened in an already-activated region, thereby restoring the resting potential. This prevents retriggering a secondary action potential (which would result in amplification of the end signal). On the other hand, when an inhibitory neurotransmitter binds with the neuron, or else a chloride ion channel (chloride ions are anionic - negatively-charged) opens, chloride ions enter the neuron, which drives the membrane potential further into the negative, thereby reducing the likelihood of action potential (signal) generation.
When an axon is not conducting an impulse is known as?
Resting Potential
What are the electrically charged molecules involved in nerve impulses called?
axon
What occurs in repolarization?
As the axon repolarizes Na+ channels open to bring the cell from a resting state -70mv to -55mv and grater (grater being -55mv through 0mv).
What happens when a neuron becomes excitable?
A neuron which is excitable is in its RESTING STATE, which means that it is POLARIZED, and thus able to be stimulated into an action potential.
What happens if the permeability of a resting axon to sodium ion increases?
inward movement of sodium will increase and the membrane will depolarize.
What happens when the permeability of a resting axon to sodium ion changes?
Inward movement of sodium ions will increase and the membrane will depolarize
How does the neuron moves a resting place to firing and then back to resting state?
The event in which a neuron's membrane potential rapidly rises from its resting potential and then falls back to its resting potential is called an action potential.The neuron fires an action potential and returns to its resting state in the following manner:Initially the resting potential of the inside of the cell membrane of a neuron with respect to the outside is about -70mV (this condition is referred to as polarized).As neural signals from inputs at the dendrites of the neuron move down the dendrites and across the soma (cell body), they arrive at the beginning of the axon, called the axon hillock; those signals are comprised of quantities of sodium ions which have been pushed to the axon hillock by an influx of sodium ions through ligand-gated sodium ion channels (ion pores which open from the action of a chemical messenger neurotransmitters in a receptor portion of the ion gate) in the dendrites which have been opened by neurotransmitters released by a pre-synaptic neuron diffusing across the synaptic cleft into receptors at the dendrite.Firing: If enough quantity of sodium ions reach the axon hillock to raise the membrane potential at that point to a threshold value of about -55mV(the trigger voltage), this is sufficient to open voltage-gated sodium ion pores in the initial segment of the axon, which allows more sodium ions in, raising the membrane voltage to from 50mV to 100mV (called depolarization), which cause nearby v-gated Na ion pores to open, which lets in more sodium ions, which open successive v-gated ion pores along the length of the axon. This moving (action) potential (voltage) is the neural impulse.Returning to resting state: during the peak of the action potential, when the membrane potential is at it greatest, sodium pores begin to close, and potassium pores are opened, and since there is more potassium inside the cell than outside, potassium ions begin to leave the neuron through those channels; with the loss of these positively charged ions, the membrane voltage becomes more and more negative, opening more potassium pores, until the membrane voltage actually undershoots the resting potential momentarily. At this point the potassium pores begin to close, and the membrane potential rises back to the resting potential.(please see the links below for additional explanations)
What happens to the size of an action potential as it continues down the axon?
I belive the size of the axon potential remains constant at a depolarisation of +40 mv and a resting potential of -70mv for most nerves. The frenquency of action potentials is the factor that determines the strength of the nerve impulse.
What is the period of time after a nerve impulse has been transmitted when it is not possible for another impulse to act upon the dendrite and the axon?
The Resting Period; over with in less than milliseconds.
What is the state when an electrical charge of a neuron is said to be at a resting potential?
The resting potential is the normal equilibrium charge difference (potential gradient) across the neuronal membrane, created by the imbalance in sodium, potassium, and chloride ions inside and outside the neuron.
Describe the path a nerve impulse travels through?
When an impulse travels to the brain, it is first received by sensory receptors, then sent through the neurons by an electrical current. When the neuron receives the signal from a sensory receptor or from another neuron, the nucleus processes the impulse and then sends it down the axon. When a neuron is resting, the inside of the cell has a negative charge caused by active transport of NA and K molecules. This is called the resting potential. When the impulse hits the axon, the electricity causes NA pumps to open, allowing a flow of positively charged the molecule into the cell, causing the charges to switch. This is called the action potential. As the impulse passes, the K pumps open, restoring the original charge. When the impulse reached the end of the axon, neurotransmitters chemically pass the impulse to the next neuron. ;
