The potential of a rod's outer segment in complete darkness is approximately _________ mV.
A) -70
B) -30
C) +30
D) +70

Question

Quizplus · Accepted Answer

The resting potential of a rod's outer segment in complete darkness is approximately -30mV. This is because in darkness, the outer segment is continuously depolarized by a relatively high concentration of cGMP, which keeps sodium channels open and leads to an influx of positive ions, bringing the membrane potential closer to sodium equilibrium potential.

The Potential of a Rod's Outer Segment in Complete Darkness