Hydraulic analogs as teaching tools for bioelectric potentials.

Hydraulic analogs of bioelectrical potentials are proposed as teaching tools in helping students with no formal background in physics and mathematics. Membrane capacitance is simulated by a water reservoir, V, whose variable level is the membrane potential. Resting membrane potential is simulated by a large capacitance reservoir of fixed level, connected to reservoir V through a tube having the role of the electrical conductance of the membrane. Injection of electrical current into the cell is simulated by injection of water into the membrane capacitance reservoir. Reversal potentials of the end-plate potential are simulated by another water reservoir, with fixed level (analogous to the reversal potential of the end-plate potential) connected to the membrane capacitance reservoir through a tube corresponding to the acetylcholine-activated ion channels. Different phases of the synaptic potential are then described using the hydraulic analogs. Hydraulic analogs have proved, in our experience, to be an efficient tool in complementing the already established electrical equivalents.