Bistability in biological systems

Bistability is also observed in physiological systems, and the phenomenon has a formal similarity with electro-kinetic phenomenon. In nerve physiology, the so-called switching mechanism in nerve cells from a rest to action potential corresponds to the above phenomena. Current-voltage curves [44, 45] similar to the above are obtained in biological systems where we have different concentrations of electrolytes across the cell membranes. 

The ratio of the values of conductance of the membrane in the two steady states is given in Table 8.3 for different cases. The same for the pyrex membrane sodium chloride system has also been recorded for the sake of comparison. 

Excitation of the squid axon membrane in iso-osmotic potassium chloride solution has been investigated [46 8] and is found to be particularly interesting. In this context, current-voltage curves were obtained by keeping (i) the current constant and (ii) the voltage constant. A typical curve [48] is shown in Fig. 8.7 which displays hysteresis. 

System Approximate ratio of conductance of solutions on the two sides of the membranes 

About 0.5 M KCI iso-osmotic solution was used. Attempt was also made to correlate the phenomena with the time course of an action potential in 0.5 M potassium chloride. 

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