# 6.021/Notes/2006-10-20

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Revision as of 13:59, 8 November 2006 by Austin J. Che (talk | contribs)

## Core conductor model

- Look at impact of topology on electrical properties
- : different potentials along the cell
- Break into lumps/nodes
- Treat as internal resistors, outer resistors, and unknown boxes connecting inside/outside (membrane potential)
- Inner conductor: resistance . is in ohms and is in ohms/m.
- Outer conductor: resistance (similar to inner conductor)
- Current through membrane: is in amps and is in A/m.
- Assume topology, Ohm's law, but nothing about the membrane
- Core conductor equations:
- is externally applied current

- The first 2 equations are continuity of current, the second two are Ohm's law

- Combining equations, we get THE core conductor equation:
- We still have assumed nothing about the membrane

- Suppose no external current. (otherwise charge would build up)
- If we know
- For action potential traveling at constant speed
- (wave equation)

- From this model alone, we find that the current at the peak of the action potential is predicted to be inwards!
- For all standard electrical elements (resistor, capacitor, inductor), we would predict outward current
- This model makes no assumption about the membrane, only that Ohm's law holds