Question

NEUROSCIENCE; SHUNTING INHIBITION
(Please see attached)

Answer 1

What I do not understand is how is the inward flow of Cl- ions equivalent to the outward flow of +ve current.

First of all, why would the current be leaving in the first place? Would it not attract the negative charge, and just remain halted in that vicinity?

Answer 2

In physics, current is normally represented as the movement of positive charge carriers (although in real life its more negative charge carriers); if the positive charge carrier is moving to the right, so will the current. Since the principal charge is Cl-, which is a NEGATIVE CHARGE CARRIER, the direction of the current is opposite of the movement of the charge. Thus, when Cl- ions enter the neuron, current must, by principle, be represented as moving OUT.