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What happens when presynaptic cell's produce action potentials?
Wiki User
∙ 11y ago
The action potential moves along the axon and releases neurotransmitters into the synapse.
When the presynaptic cell (neuron) fires the action potential, it causes voltage gated sodium ion pores to open at the initial segment of its axon (just after the axon hillock), which allows sodium ions in, which cause adjacent voltage gated sodium ion pores to open, which let in more sodium ions, which do the same thing progressively along the axon, until the action potential reaches the axon terminals, at which point the voltage opens voltage gated calcium ion pores, which cause vesicles (small membrane bounded sacs) full of neurotransmitters to move toward the end of the cell membrane and fuse there, releasing their contents into the synaptic cleft.
Wiki User
∙ 11y ago
When presynaptic cells produce action potentials, it triggers the opening of voltage-gated calcium channels in the presynaptic membrane. This influx of calcium ions into the presynaptic cell triggers the release of neurotransmitter molecules from small, membrane-bound vesicles. The released neurotransmitters then diffuse across the synapse and bind to receptors on the postsynaptic cell, generating a response in the postsynaptic cell.
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Why do not action potentials occur during the repolarization phase?
It has to do with what types of channels are open during this phase. In the repolarization phase the number of potassium channels are increased and the number of sodium channels are decreased. This allows for action potentials to not occur. Otherwise, the action potentials would add up and produce tetany.
Which cell must have action potentials to produce one or more action potentials in the postsynaptic cell?
A neuron (nerve cell) receives dendritic input in order to generate action potentials to transmit signals of the same. After the action potential triggers release of neurotransmitters in the axonal terminal of that neuron, those neurotransmitters propagate the signal forward to the next neuron, and so forth.
What is synaptic facilitation?
an action will happen cause of axo-axonal syanapse,which can facilitate the nerve impulse transmitting from presynaptic membrane to post synaptic membrane. In the axo-axonal synapse one axon is secreting serotonin which can influence to close some of K+ channels in the other neuron to maintain a prolonged action potential by slowing down the repolarization. as long as action potential is there it can stimulate the presynaptic membrane to release neurotransmitters towards postsyanptic membrane so prolonged action potential will help to stimulate more the Post synaptic membrane and give a strong impulse this is called presynaptic facilitation
How does an action potential differ from a graded potential?
Action potentials also known as spikes, differ from graded potentials in that they do not diminish in strength as they travel through the neuron.
Where do most action potentials originate?
initial segment
What happens after nerve signal reaches a synaptic knob?
In general, action potentials that reach the synaptic knobs cause a neurotransmitter to be released into the synaptic cleft. The arrival of the action potential opens voltage-sensitive calcium channels in the presynaptic membrane.
Why do not action potentials occur during the repolarization phase?
It has to do with what types of channels are open during this phase. In the repolarization phase the number of potassium channels are increased and the number of sodium channels are decreased. This allows for action potentials to not occur. Otherwise, the action potentials would add up and produce tetany.
Which cell must have action potentials to produce one or more action potentials in the postsynaptic cell?
A neuron (nerve cell) receives dendritic input in order to generate action potentials to transmit signals of the same. After the action potential triggers release of neurotransmitters in the axonal terminal of that neuron, those neurotransmitters propagate the signal forward to the next neuron, and so forth.
Do action potentials become weaker with distance?
action potentials are non-decremental and do not get weaker with distance.
What is synaptic facilitation?
an action will happen cause of axo-axonal syanapse,which can facilitate the nerve impulse transmitting from presynaptic membrane to post synaptic membrane. In the axo-axonal synapse one axon is secreting serotonin which can influence to close some of K+ channels in the other neuron to maintain a prolonged action potential by slowing down the repolarization. as long as action potential is there it can stimulate the presynaptic membrane to release neurotransmitters towards postsyanptic membrane so prolonged action potential will help to stimulate more the Post synaptic membrane and give a strong impulse this is called presynaptic facilitation
The all or none principle states that?
all stimuli great enough to bring the membrane to threshold will produce identical action potentials. :)
What do intercalated discs transfer from cell to cell?
action potentials, ionic currents, the force of contraction and ionic currents and action potentials only
What is the difference between presynaptic and postsynaptic neurons?
Presynaptic neurons release the neurotransmitter in response to an action potential. Postsynaptic neurons receive the neurotransmitter (and can however become presynaptic to the next nerve cell, if the neurotransmitter has stimulated the cell enough).
How does an action potential differ from a graded potential?
Action potentials also known as spikes, differ from graded potentials in that they do not diminish in strength as they travel through the neuron.
Communication in the nervous system depends on?
action potentials
Where do most action potentials originate?
initial segment
A nerve impulse consists of a wave of?
Action Potentials
