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Several assumptions are made in deriving the GHK flux equation (Hille 2001, p. 445) : The membrane is a homogeneous substance; The electrical field is constant so that the transmembrane potential varies linearly across the membrane; The ions access the membrane instantaneously from the intra- and extracellular solutions
Leak channels account for the natural permeability of the membrane to ions and take the form of the equation for voltage-gated channels, where the conductance is a constant. Thus, the leak current due to passive leak ion channels in the Hodgkin-Huxley formalism is I l = g l e a k ( V − V l e a k ) {\displaystyle I_{l}=g_{leak}(V-V_{leak})} .
A cell membrane is simplified as lipid bilayer plus membrane skeleton. The skeleton is a cross-linking protein network and joints to the bilayer at some points. Assume that each proteins in the membrane skeleton have similar length which is much smaller than the whole size of the cell membrane, and that the membrane is locally 2-dimensional ...
A drainage equation is an equation describing the relation between depth and spacing of parallel subsurface drains, depth of the watertable, depth and hydraulic conductivity of the soils. It is used in drainage design. Parameters in Hooghoudt's drainage equation. A well known steady-state drainage
The ionic charge determines the sign of the membrane potential contribution. During an action potential, although the membrane potential changes about 100mV, the concentrations of ions inside and outside the cell do not change significantly. They are always very close to their respective concentrations when the membrane is at their resting ...
The total permeate flow from a membrane system is given by following equation: = Where Qp is the permeate stream flowrate [kg·s −1], F w is the water flux rate [kg·m −2 ·s −1] and A is the membrane area [m 2] The permeability (k) [m·s −2 ·bar −1] of a membrane is given by the next equation:
There are several modes by which membrane channels operate. The most common is the gated channel which requires a trigger, such as a change in membrane potential in voltage-gated channels, to unlock or lock the pore opening. Voltage-gated channels are critical to the production of an action potential in neurons resulting in a nerve impulse.
Where is the solute permeability coefficient and is the trans-membrane concentration differential for the solute. It is clear from this governing equation that a solute will diffuse from an area of high concentration to an area of low concentration if solutes can diffuse across a membrane.