A neural impulse is transmitted along the neuronal

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A neural impulse is transmitted along the neuronal membrane through the depolarization of consecutive neighboring regions. When a region on the internal surface of the membrane is depolarized, it becomes more positive in relation to the neighboring internal region. As a result, positive electrical charges (ions) move towards this more negative region and voltage-gated sodium channels are activated and opened. The action potential then linearly moves along the membrane until reaching the presynaptic region of the axon. The Nervous System Review - Image Diversity: axonal impulse transmission 49. Through which structure is a neural impulse transmitted from one cell to another? What are its parts? The structure through which a neural impulse passes from one cell to another is the synapse. The synapse is composed of the presynaptic membrane in the terminal portion of the axon of the transmitter cell, the synaptic cleft (or synaptic space) and the postsynaptic membrane in the dendrite of the receptor cell. 50. How does synaptic transmission between neurons take place?
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The propagation of the action potential along the axon reaches the region immediately anterior to the presynaptic membrane, causing its permeability to calcium ions to change and causing these ions to enter the cell. In the presynaptic area of the axon, there are a large amount of neurotransmitter-filled vesicles that, by means of exocytosis activated by the calcium influx, release the neurotransmitters into the synaptic cleft. The neurotransmitters then bind to specific receptors of the postsynaptic membrane. (The binding of neurotransmitters to their receptors is reversible, that is, the neurotransmitters are not consumed during the process.) With the binding of the neurotransmitters to the postsynaptic receptors, the permeability of the postsynaptic membrane is altered and the depolarization that will lead to the first action potential of the postsynaptic cell begins. The Nervous System Review - Image Diversity: synaptic transmission 51. What are some important neurotransmitters? The following are important neurotransmitters: adrenaline (epinephrine), noradrenaline (norepinephrine), acetylcholine, dopamine, serotonin, histamine, gaba (gamma aminobutyric acid), glycine, aspartate and nitric oxide. 52. Since neurotransmitters are not consumed during the synaptic process, what mechanisms are used to reduce their concentrations in the
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synaptic cleft after they have been used? Since the binding of neurotransmitters to postsynaptic receptors is reversible, after these neurochemicals carry out their role, they must be eliminated from the synaptic cleft. Neurotransmitters then bind to specific proteins that carry them back to the axon they came from in a process called neurotransmitter re-uptake. They can also be destroyed by specific enzymes, such as acetylcholinesterase, an enzyme that destroys acetylcholine. In addition, they can simply diffuse out of the synaptic cleft. The Nervous System Review - Image Diversity: neurotransmitter reuptake 53. Fluoxetine is an antidepressant drug that uses an action mechanism related to synaptic transmission. What is that mechanism?
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