Vision: Transduction and the Two Retinal Visual Systems

[@itamar.j.rachailovich]

I am grateful for your videos!!! I learnt a lot from you. But I must correct 1 thing: The pigment is the RETINAL, and the protein is opsin. when the configuration of the RETINAL is 11-cis the affinity between the opsin and the RETINAL is high so the opsin binds to RETINAL and thus the concentration of free opsin is low. However, when the configuration of the RETINAL is "all trans" the affinity between the pigment(RETINAL) and protein(opsin) decreases dramatically and is very low and thus the opsin is released from the RETINAL and becomes free. Now the free opsin binds to G protein and activates it. the activated G-protein activates (phosphodiesterase) and activates it. the active phosphodiesterase breaks cGMP to '5-GMP and thus shut the sodium channels which make the cell hyperpolarized

[@PaulMerritt]

There is an error in this video regarding transduction - photon capture does not generate an action potential, rather it actually hyperpolarizes the cell and is thus inhibitory.

[@lefrog3851]

Hi,I have a question.Does the hyperpolarization activity of the cone depends on the frequency of the photon absorbed or the amplitude of the electromagnetic wave?

[@gamma-girl]

During photon capture, hyperpolarization occurs due to the leaky potassium channels that closes Ca2+ channels in the synaptic terminal resulting in a decrease in the inhibitory glutamate transmitter thus increasing the graded potentials in the bipolar cells resulting in an action potential in ganglion cells and propagation of action potentials to the visual cortex.