Synaptic vesicle
nerve impulse
When the _____________reaches the ends of the axon the neurotransmitter is released and it diffuses to the muscle cell membrane to combine with receptors there?Sarcolemma
When an action potential reaches the axon terminal, it triggers the opening of voltage-gated calcium channels. Calcium ions enter the axon terminal, leading to the fusion of neurotransmitter-containing vesicles with the synaptic membrane. The neurotransmitter is then released into the synaptic cleft where it can bind to receptors on the postsynaptic neuron.
The impulse itself does not actually cross the gap, which is called a synapse by the way, instead it stimulates the realease of a neurotransmitter from vesicles. When the neurotransmitter reaches the other side of the synapse it binds proteins on the opposing membrane and in doing so stimulates the membrane to continue the action potential on the mect cell.
Calcium ions trigger the release of neurotransmitter at the presynaptic membrane. When an action potential reaches the presynaptic terminal, it causes voltage-gated calcium channels to open, allowing calcium ions to enter the cell. The influx of calcium ions triggers the fusion of synaptic vesicles with the presynaptic membrane, leading to the release of neurotransmitter into the synaptic cleft.
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.
Most neurons have a chemical synapse, which is to say that a substance called a neurotransmitter is released from the first neuron (called pre-synaptic) to the next neuron called (post-synaptic). How is the release triggered? When an action potential reaches the terminus (end of the axon) there are specialized calcium channels that are opened (voltage-gated). The calcium bind so the inner membrane and triggers the release of small membrane bound vesicles which spill out their contents of neurotransmitter into the synaptic cleft. The neurotransmitter binds to specific receptors on the post-synaptic membrane and that causes the action potential to propagate on (or for the neurotransmitter to cause an action like a muscle contraction).
Communication across a synapse is initiated by the release of a neurotransmitter from the axon terminal of the presynaptic neuron. When an action potential reaches the axon terminal, it triggers the influx of calcium ions, leading to the fusion of neurotransmitter-containing vesicles with the presynaptic membrane. This process causes the neurotransmitters to be released into the synaptic cleft, where they bind to receptors on the postsynaptic neuron and facilitate communication.
Calcium ions cause the neurotransmitter vesicles to fuse with the axon terminal. When an action potential reaches the axon terminal, voltage-gated calcium ion pores are opened, allowing calcium ions into the axon terminal. These ions initiate the release of neurotransmitter vesicles stored on elements of the cytoskeleton located near the presynaptic membrane; they then travel to the presynaptic membrane, where they first dock, and then fuse with the presynaptic membrane, forming an opening or pore through which the neurotransmitters are released into the synaptic cleft.
1. Nerve impulse reaches synaptic terminal. 2. Synaptic vesicles move to and merge with the presynaptic cell membrane of the motor neuron. 3. Acetylcholine is released into and diffuses across the synaptic cleft. 4. Acetylcholine binds to receptors on the postsynaptic cell membrane of the muscle fiber.
neurotransmitter
Calcium ions (Ca²⁺) must flow into the presynaptic cell for neurotransmitter release. When an action potential reaches the presynaptic terminal, voltage-gated calcium channels open, allowing Ca²⁺ to enter the cell. This influx of calcium triggers the fusion of neurotransmitter-containing vesicles with the presynaptic membrane, leading to the release of neurotransmitters into the synaptic cleft.