Resistors and Conductors

 

Currents flow through resistors or conductors. The two terms actually complement one another the former emphasizes the barriers to current flow, while the latter emphasizes the pathways for flow. In quantitative terms, resistance R (units: ohms is the inverse of conductance G (units: Siemens (S)); thus, infinite resistance is zero conductance.

In electrophysiology, it is convenient to discuss currents in terms of conductance because side-by-side ("parallel")conductances simply summate. The most important application of the parallel conductances involves ion channels.

When several ion channels in a membrane are open simultaneously, the total conductance is simply the sum of the conductances of the individual open channels.

 

 

Summation of Conductance:

 

Conductances in parallel summate together, whether they are resistors or ion channels.