From the constitution of the nervous system, neurons involved in the processing and transport of various information. These operations are performed through ion fluxes through their cell membrane.
The intracellular and extracellular environments contain ions in solution. These ions are not distributed symmetrically on either side of the membrane that surrounds the cell. For example, sodium (Na +) and potassium (K +) Are the predominant respectively outside and inside the cell cations, and calcium (Ca2 +) is to ten thousand times less abundant in the intracellular environment and in the extracellular medium. Yet ions tend (law of osmosis) to balance their concentration diffusion in both environments that separates the membrane: sodium tends to enter the cell and potassium out. However, the cell maintains an active ionic segregation using ion carriers (eg ATPases) present in the cell membrane. Accordingly, due to a slight excess of extracellular and intracellular ions positively charged negatively charged ions, intracellular electric potential different from 50 to the extracellular potential 100mV.
Ion distribution, and thus the electric potential difference, can be modified by abruptly
opening channels located in the membrane of neurons (cf.CANAUX ION). The channels are formed by proteins that selectively allow certain ions to pass. The effect of the opening of a channel depends on the nature of these ions. For example, the opening of the sodium channel permeable to a product of this ion influx into the cell, which will bring the intracellular potential of the extracellular potential, one speaks then depolarization. Opening a channel permeable to potassium will cause the output of the ion, which will increase the potential difference: this is called hyper polarization. Opening of the channels is controlled either by chemical signals, or by changes in trans membrane electric potential difference. With these different types of channels, the neuron performs transport operations and transmitting information integration.
Transport information in the axon is provided by two types of channels activated by depolarization
respectively, permeable to sodium and potassium. When the membrane of the neuron is depolarized beyond a certain threshold, then the sodium channels open potassium channels. This produces a brief sequence of depolarization then hyper polarization of the membrane, called action potential Followed by return to the initial state. Distribution channels along the axon enables the spread of potential of action, and therefore the transport of an electrical signal from the cell body to endpoints synaptic. The duration of the action potential is of the order of a millisecond, and velocity varies from a few meters to several hundred meters per second. One and the other depends on the type neuron and the organization of nervous tissue around the axon.
The intracellular and extracellular environments contain ions in solution. These ions are not distributed symmetrically on either side of the membrane that surrounds the cell. For example, sodium (Na +) and potassium (K +) Are the predominant respectively outside and inside the cell cations, and calcium (Ca2 +) is to ten thousand times less abundant in the intracellular environment and in the extracellular medium. Yet ions tend (law of osmosis) to balance their concentration diffusion in both environments that separates the membrane: sodium tends to enter the cell and potassium out. However, the cell maintains an active ionic segregation using ion carriers (eg ATPases) present in the cell membrane. Accordingly, due to a slight excess of extracellular and intracellular ions positively charged negatively charged ions, intracellular electric potential different from 50 to the extracellular potential 100mV.
Ion distribution, and thus the electric potential difference, can be modified by abruptly
opening channels located in the membrane of neurons (cf.CANAUX ION). The channels are formed by proteins that selectively allow certain ions to pass. The effect of the opening of a channel depends on the nature of these ions. For example, the opening of the sodium channel permeable to a product of this ion influx into the cell, which will bring the intracellular potential of the extracellular potential, one speaks then depolarization. Opening a channel permeable to potassium will cause the output of the ion, which will increase the potential difference: this is called hyper polarization. Opening of the channels is controlled either by chemical signals, or by changes in trans membrane electric potential difference. With these different types of channels, the neuron performs transport operations and transmitting information integration.
respectively, permeable to sodium and potassium. When the membrane of the neuron is depolarized beyond a certain threshold, then the sodium channels open potassium channels. This produces a brief sequence of depolarization then hyper polarization of the membrane, called action potential Followed by return to the initial state. Distribution channels along the axon enables the spread of potential of action, and therefore the transport of an electrical signal from the cell body to endpoints synaptic. The duration of the action potential is of the order of a millisecond, and velocity varies from a few meters to several hundred meters per second. One and the other depends on the type neuron and the organization of nervous tissue around the axon.
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