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How do neurotransmitters initiate action potentials?
Neurotransmitters bind to specific receptors on the postsynaptic neuron, leading to changes in the membrane potential and potentially causing depolarization. If the depolarization reaches a threshold, it triggers the opening of voltage-gated ion channels, allowing sodium ions to flow into the cell, generating an action potential. This electrical signal then propagates along the neuron's axon to transmit information to other neurons.
How does calcium channels help a synapse create a action potential?
They let calcium ions in, which cause neurotransmitters to be released into a synapse, which cause a neural impulse to flow down a dendrite toward the axon hillock, where the action potential is generated. In more detail: The first steps occur in an axon terminal, which is where the calcium channels are located. When calcium channels are caused to open by the arrival of an action potential at an axon terminal, calcium ions enter the axon terminal, where the calcium ions bind to vesicles containing neurotransmitters, which causes the vesicles to fuse to the cell membrane, forming an opening through which the neurotransmitters are released into the synaptic cleft. The neurotransmitters diffuse quickly across the synaptic cleft (the gap between two neurons), where they fit into receptors on the surface of the postsynaptic neuron, usually on a dendrite or a dendritic spine, and cause ligand-gated sodium ion pores to open, allowing sodium ions into the postsynaptic neuron, which causes an electrotonic impulse to travel down a dendrite, across the soma, to the axon hillock, where the impulses are summed up, and if a sufficient voltage potential is realized, an action potential is initiated in the initial segment of the axon.
Where are the 6 neurotransmitters located in the neurotransmitters?
Neurotransmitters are located within the synaptic vesicles of the presynaptic neuron. When an action potential reaches the axon terminal, these neurotransmitters are released into the synaptic cleft to communicate with the postsynaptic neuron.
Are neurotransmitters stored within motor neuron endings?
No, neurotransmitters are stored in vesicles within motor neuron endings. When an action potential travels down the neuron, these vesicles release neurotransmitters into the synaptic cleft to transmit signals to target cells.
Why is action potential important?
Action potentials play a crucial role in transmitting electrical signals along neurons, allowing for communication within the nervous system. They are essential for the initiation and propagation of nerve impulses, leading to various physiological functions such as muscle contraction, sensation, and behavior. Action potentials also help maintain the resting membrane potential of cells and facilitate information processing in the brain.
