Currents across cell membranes Hodgkin-Huxley

In 1952 Hodgkin and Huxley (3) proposed a mathematical form that could represent the currents measured across cell membranes. They noted (3) that these equations can be given a physical basis if we assume that potassium can only cross the membrane when four similar particles occupy a certain region of the membrane. .. and if the sodium conductance is assumed to be proportional to the number of sites on the inside of the membrane which are... 

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