In: Anatomy and Physiology
Which of the following is not part of the photoreceptors Guanylyl cyclase
Transducin
Phosphodiesterase
Voltage gated sodium channels
Opsin
Answer d)Voltage gated Sodium channels
It is CGMP gated sodium channeld and not voltage gated sodium channels .
Steps of Phototransduction
* Light falls on Cornea and then through Lens it reaches the Retina.Here light is absorbed by retinal molecule and then is passes through Bipolar and Retinal cells in Retina
*When light falls on the the outer Segment of Rods ( 11 cis retinal + Opsin) it dissociate into All trans Retinal and Opsin got separates out
*After formation of All trans retinal ,it is the trnanducin which is activated by releasing GDP and get converted into activated Transducin with GTP .
*Activated transducin activate Phosphodiesterases enzyme which is responsibe for degradation of Cyclic GMP ( guanosine monophoshate )
*Cyclic GMP is responsible for opened Na+ Channels .
*Separated opsin produces these reactions tleads to close some of the Na+ channels, and the result is a hyperpolarizing receptor potential.
So guanyl cyclase include Transducin ,phosphodiesterase and Voltage gated Sodium channels but not Opsin .