In membrane biophysics sometimes used interchangeably with cell potential, but applicable to any lipid bilayer or membrane. Hence every organelle and every membranous compartment (such as a synthetic vesicle) has a transmembrane potential (although the size of this potential may be zero). The transmembrane potential is the voltage "drop" or the difference in voltage between one face of a bilayer and its immediate opposite face. The property need not be uniform throughout the cell or compartment, but under some conditions may vary between one patch of membrane and another. A localized change in potential occurs at the synapse of nerve cell, for example, with the opening of ion channels by neurotransmitter. Likewise during an action potential, the magnitude of the transmembrane potential will vary in time and space along a nerve fiber. Strictly, it is the transmembrane potential or transmembrane electric field, and not the cell potential that controls the transmembrane flow of charged solutes and the activity of voltage-gated ion channels.
The resting membranepotential of a neuron is about -70 mV (mV=millivolt) - this means that the inside of the neuron is 70 mV less than the outside.
Also, when the threshold level is reached, an action potential of a fixed sized will always fire...for any given neuron, the size of the action potential is always the same.
Action potentials are caused by an exchange of ions across the neuronmembrane.
Hence every organelle and every membranous compartment (such as a synthetic vesicle) has a transmembranepotential (although the size of this potential may be zero).
The transmembranepotential is the voltage "drop" or the difference in voltage between one face of a bilayer and its immediate opposite face.
Strictly, it is the transmembranepotential or transmembrane electric field, and not the cell potential that controls the transmembrane flow of charged solutes and the activity of voltage-gated ion channels.
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