Question

The axoplasm of an axon has a resistance Rax. The axon's membrane has both a resistance (Rmem) and a capacitance (Cmem). A single segment of an axon can be modeled by a circuit with Rmem and Cmem in parallel with each other and in series with an open switch, a battery, and Rax?.
Imagine the voltage of the battery is ?V?.

Imagine that after a very long time there is a current I going through the battery. The potential difference across the membrane can be written as I Rmem.

Write down another expression for the potential difference across the membrane using all or some of the given variables, except Rmem.

Answer 1

Answer:

The expression is Vmem = ΔV - I*Rax

Explanation:

According to the picture, if switch S is closed, the Cmem will be short. If Vcap = 0, the current flows through the capacitor only (not through Rmem), thus Vmem = 0 after closing S.

When C is fully charged, then we have:

Vmem = ΔV - I*Rax