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Where is the density of voltage gated sodium channels the greatest?
Wiki User
∙ 15y ago
Perhaps the neuromuscular junction (NMJ).
Wiki User
∙ 15y ago
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What is The region of a neuron with voltage-gated sodium channels?
soma
A nerve impulse results from?
It results from the opening of voltage-gated sodium ion channels, causing an influx of sodium ions (influx of positively-charged ions), depolarizing the neuronal membrane.
How does myelin increase the speed of nerve impulse conduction?
The way an action potential propagates is by opening voltage-gated sodium channels which depolarize the cell. Think about how long it would take to conduct an action potential if you had to open channels along the entire length of the axon and wait for sodium influx. In the case of the myelinated nerve fibers, the myelin sheath covers large portions of the axon, leaving uncovered spaces known as nodes of Ranvier. The sodium channels in a myleinated nerve fiber are only at the nodes of Ranvier. So one sodium channel opening depolarizes a much greater length of the axon until it reaches the next node of Ranvier, where the voltage-gated sodium channels open and this cycle continues. In essence the AP "hops" around, covering much greater distance in a shorter amount of time.
Mechanism that restores the resting membrane voltage and intracellular ionic concentrations?
The Sodium Potassium Pump (opposed to the channels)
Opening sodium channels in the in the axon membrane causes?
Depolarization of the cell membrane. When the sodium channels open there is a rush of sodium ions down their concentration gradient into the cell. As they carry positive charge they reduce the potential difference (inside negative) across the membrane of the neuron.
What is The region of a neuron with voltage-gated sodium channels?
soma
What cell gates open immediately after action potential peak?
Sodium and potassium voltage gated ion channels.
What does TTX do to voltage-gated Na channels?
Tetrodotoxin (TTX) is a natural inhibitor and blocks single sodium channels in an all-or-none manner.
Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials?
Sodium channels. A neuron's membrane potential may depolarize for many reasons (neurotransmitters, mechanical deflection, electrical synapse, etc). When that membrane depolarizes to the point of its threshold of activation, then voltage gated channels open up an allow an influx of sodium into the cell. This rapidly depolarizes the cell's membrane, causing that upward peak or rising phase to occur.
What type of channels that are present within the varicosities of autonomic neurons are absent from the axon terminal of other neurons?
Voltage-gated Sodium ions and Potassium ions channels
A nerve impulse results from?
It results from the opening of voltage-gated sodium ion channels, causing an influx of sodium ions (influx of positively-charged ions), depolarizing the neuronal membrane.
Do potassium channels open and sodium channels close during repolarization phase of the action potential?
They both stay open.If sodium channels were to remain closed, there wouldn't be any repolarization. The Potassium concentration gradient would keep pumping Potassium ions out of the cell and the Potassium electrical gradient would drive Potassium ions into the cell, thus maintaining the equilibrium potential of -90 mV.No repolarization would occur if the sodium channels are closed.The above is not correct.During the depolarization phase, BOTH VOLTAGE-GATED SODIUM & POTASSIUM channels open.Once the cell reaches close to sodium's equilibrium potential, the VOLTAGE-GATED sodium channel closes.The VOLTAGE-GATED potassium channel opens around this time(The voltage gated potassium channel is very slow to open; it fully opens around the same time the voltage gated sodium channel closes) causing repolarization.The cell experiences hyperpolarization because the voltage gated potassium is also slow to close.Once fully closed, the cell depolarizes back to resting potential.Also, the picture is a picture of the AP in cardiac muscle which differ from skeletal muscle.The plateau is due to voltage-gated calcium channel that opens during the AP.
How is an action potential propagated down an axon after voltage-gated sodium channels open in a region of the neuron's membrane?
The entry of sodium ions into the neuron and their diffusion to adjacent areas of the membrane causes those portions of the membrane to become depolarized and results in the opening of voltage-gated sodium channels farther down the axon, which release potassium ions to the outside, returning the charge to its previous state
After depolarization phase of an action potential the resting potential is restored by?
the opening of voltage-gated potassium channels and the closing of sodium activation gates.
What is the primary action during depolarization of an action potential?
Sodium ions flow into the neuron via voltage-gated sodium ion channels, driving the membrane potential into the positive. Beyond the threshold, more sodium ion channels are opened, causing the influx of sodium further downstream, and the process repeats, propagating the action potential down the axon.
What is a voltage-gated membrane channel?
Voltage-gated channels are proteins in the cell membrane which open when stimulated by a voltage (an electrical signal). The voltage causes the channel to open, thereby allowing the entry or exit of whatever substance the channel relates to. An example of this the the voltage-gated sodium channels on neurons. When an action potential (a voltage), passes over the cell, it open these channels and allows sodium to enter the cell.
What ion flows into a nerve cell when an axon's membrane depolarizes?
During the depolarization phase, sodium ions enter the cell through the open ion-channels (Na+ influx).
