When the retina molecule absorbs light the 11- cis form of the bound retina molecule will straighten and become 11- trans, which activates the opsin molecule. Opsin activates the G protein, Transduction, which activates phosphodiesterase, and enzyme that breaks down cyclic - GMP. This removes them from the sodium channels and makes those channels inactive. This causes a decrease in sodium ions entering the cytoplasm. This reduces the dark current. However, active transport continues to take sodium ions from the cytoplasm even though the sodium channels are closed. As a result, the transmembrane potential drops to -70mV and hyper polarizes. This causes less neurotransmitters to be released and the adjacent cell notice that the photoreceptor
