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By a chemical released by an axon.
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ReneMost 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).
When a nerve impulse reaches the end of a neuron, it triggers the release of neurotransmitters. These neurotransmitters cross the synapse and bind to receptors on the next neuron, causing a new electrical signal to be generated. This new signal then continues along the next neuron, allowing the nerve impulse to travel.
The electrical impulse doesn't cross the synaptic cleft. Rather the action potential triggers the entry of calcium into the nerve terminus which then leads to the fusion of the synaptic vesicles with the membrane and the release of neurotransmitter. On the other side the synaptic cleft the neurotransmitter opens ligand dependent voltage channels and triggers an action potential in the next neuron. There are such things as cells where a tight junction allows a direct electrical stimulation of the post-synaptic neuron. This is the situation in heart and in smooth muscle.
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 potentialto propagate on (or for the neurotransmitter to cause an action like a muscle contraction).
Nerve impulses travel from neuron to neuron via neurotransmitters that are released into the synapse by the sending neuron. The neurotransmitter binds to a receptor on the receiving neuron. When enough receptors are triggered, an action potential is initiated on the receiving neuron.
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What is an axoplasm?
An axoplasm is the cytoplasm of an axon - a nerve fibre which conducts nerve impulses away form the body of a cell, to a synapse.
What carries messages away from the nerve cell body toward the synapse?
Axons carry messages away from the nerve cell body toward the synapse. These long fibers transmit electrical impulses and release neurotransmitters at the synapse to communicate with other cells.
When nerve impulses from several presynaptic neurons stimulate a single postsynaptic neuron at the same time it is called?
chemical synapse
What is the point at which a nerve impulse is sent from one nerve cell to another?
The point at which a nerve impulse is sent from one nerve cell to another is called a synapse. At the synapse, the electrical signal in the form of an action potential triggers the release of neurotransmitters from the presynaptic neuron, which then bind to receptors on the postsynaptic neuron to transmit the signal.
What helps carry nerve impluses across the synapse?
Neurotransmitters encased in vesicles and diffusing across the synaptic gap.
