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An action potential is triggered when a sufficiently strong neural signal reaches the trigger zone of a neuron, which is the axon hillock or the initial segment of the axon.
The trigger zone contains a dense concentration of voltage-gated sodium-ion pores, which open and allow sodium ions into the neuron when the membrane voltage there rises from about -70mV resting potential to a trigger threshold of about -55mV as a result of a summing of inputs to the neuron.
The resulting inrush of sodium ions through the ion pores is the beginning of the action potential.
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RafaAn action potential is triggered when a neuron's membrane potential reaches a certain threshold level, typically around -55mV. This threshold is reached when excitatory signals from other neurons cause the membrane potential to depolarize sufficiently to open voltage-gated sodium channels, allowing a rapid influx of sodium ions. This causes a rapid change in membrane potential, leading to the generation and propagation of an action potential along the neuron.
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What triggers the action potential?
A temporary accumulation of sodium ions at the axon hillock which yields a voltage sufficient to open voltage-gated ion pores on the axon is what triggers an action potential.
What change in membrane potential triggers an action potential?
A sudden increase in membrane potential, typically from a resting membrane potential of around -70mV to a threshold potential of around -55mV, triggers the opening of voltage-gated sodium channels leading to depolarization and initiation of an action potential.
When an action potential reaches the end of a neuron it triggers the release of?
neurotransmitters from the synaptic vesicles into the synapse. These neurotransmitters then bind to receptor proteins on the adjacent neuron, initiating a new action potential in the postsynaptic neuron.
What is the sequence of events that follow a threshold potential?
Following a threshold potential, voltage-gated sodium channels open, allowing sodium ions to rush into the cell, depolarizing the membrane. This triggers an action potential that spreads down the length of the neuron. Once the action potential reaches the end of the neuron, it triggers the release of neurotransmitters into the synaptic cleft to communicate with the next neuron.
What has to be crossed before the neuron fires?
The threshold potential must be reached for the neuron to fire. This is the level of depolarization that triggers an action potential to be generated and propagated along the neuron.
