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How will the signaling of a neuron be affected if the voltage-gated sodium channels open at a more negative membrne potential?
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What is happening to voltage-gated channels at this point in the action potential?
Na+ channels are inactivating, and K+ channels are opening.
What is the primary feature of a neuron that prevents the action potential from traveling back from where it just passed?
Antidromic conduction, or the process of an action potential traveling backwards, is possible. However, regardless of the direction of the action potential, it is propagated by voltage-gated ion channels. Whenever these channels open, there is a sudden exchange of ions, after which the channels snap shut. During this period, known as the refractory period, the channels will not reopen, and thus an action potential will not be able to reverse direction.
What are the Stages of nerve impulses?
The action potential has 5 main phases:1) stimulation/rising phase - depolarization caused by influx of sodium ions at the axon hillock; potential increases from a resting potential of -70 mV2) peak phase - depolarization and membrane potential reaches a peak, with sodium channels open maximally, at about +40 mV3) falling phase - potassium channels open in response, causing a subsequent reduction in membrane potential, and the neuron begins to repolarize4) hyperpolarization/undershoot phase - more potassium channels stay open after sodium channels close, causing a hyperpolarization of the neuronal membrane, bringing the potential down below its initial resting potential (below -70 mV)5) refractory phase - potassium channels begin to close, allowing the membrane potential to revert back to the resting potential of -70 mV; during this phase, the probability of the nerve being able to refire is extremely low, thus allowing for a delay between action potentials
What causes the rapid change in the resting membranes potential that initiates an action potential?
In muscle cells the inward current is a sodium + calcium flow through acetycholine activated channels as well as through voltage sensitive calcium channels.
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.
Which channels support signaling?
D channels
How do non functional sodium channels affect the signaling capabilities of neurons?
When sodium enters the neuron, it depolarizes it. This means that the neuron becomes more positive. This can lead to the neuron reaching threshold and then initiate an action potential. When the sodium channels are NOT functional, the sodium can not enter and depolarize it. Therefore the threshold can not be met and action potential will not occur. If the sodium channels are inactive in an nociceptive neruon (carries information about pain), then the it will prevent you from feeling pain.
What is signal?
In telephony, signaling is the exchange of information between involved points in the network that sets up, controls, and terminates each telephone call. In in-band signaling , the signaling is on the same channel as the telephone call. In out-of-band signaling , signaling is on separate channels dedicated for the purpose.
What is happening to the voltage gated channels at this point in the action potential?
Na+ channels are inactivating, and K+ channels are opening.
What is happening to voltage-gated channels at this point in the action potential?
Na+ channels are inactivating, and K+ channels are opening.
Which ion channels open in response to a change in membrane potential?
voltage-gated ion channels
What changes occur in the neuron during an action potential?
Resting Potential: the potential remains sameAction Potential: potential causes the opening of voltage-gated sodium channels
Which membrane potential occurs because of the influx of Na plus through chemically gated channels in the receptive region of a neuron?
An excitatory postsynaptic potential, a type of graded potential, occurs because of the influx of Na+ through chemically gated channels in the receptive region, or postsynaptic membrane, of a neuron. Graded potentials are generated by chemically gated channels, whereas action potentials are produced by voltage-gated channels.
What is the primary feature of a neuron that prevents the action potential from traveling back from where it just passed?
Antidromic conduction, or the process of an action potential traveling backwards, is possible. However, regardless of the direction of the action potential, it is propagated by voltage-gated ion channels. Whenever these channels open, there is a sudden exchange of ions, after which the channels snap shut. During this period, known as the refractory period, the channels will not reopen, and thus an action potential will not be able to reverse direction.
When an action potential arrives at the axon terminal of motor neuron which ion channels open?
voltage-gated calcium channels
What are the Stages of nerve impulses?
The action potential has 5 main phases:1) stimulation/rising phase - depolarization caused by influx of sodium ions at the axon hillock; potential increases from a resting potential of -70 mV2) peak phase - depolarization and membrane potential reaches a peak, with sodium channels open maximally, at about +40 mV3) falling phase - potassium channels open in response, causing a subsequent reduction in membrane potential, and the neuron begins to repolarize4) hyperpolarization/undershoot phase - more potassium channels stay open after sodium channels close, causing a hyperpolarization of the neuronal membrane, bringing the potential down below its initial resting potential (below -70 mV)5) refractory phase - potassium channels begin to close, allowing the membrane potential to revert back to the resting potential of -70 mV; during this phase, the probability of the nerve being able to refire is extremely low, thus allowing for a delay between action potentials
How does graded potential occur?
Graded potential occurs when triggered by a stimulus and gated ion channels open these gated channels can either be chemically gated or mechanically gated. In order to have graded potential threshold must be met in order to generate action potential. Good day!
