Rods- consist rhodopsin Impotent for retinal sensitivity (dim light, see in the drak) scotopic vision, most of them located in the peripheral parts of the retina. Cones- consist photopsin, important for visual acuity (see if square or circle etc... And for color vision (photopic vision), most of them located in the fova centralis (in the mecula lutea) • More rods Tham cons. Dark to light adaptaion: 1. The pupils constrict 2. Bleaching photo pigments 3. Rhodopsin (11 cis retinal+ opsin) hit with light and converted to all trans retinal and opsin released 4. Photopsin also broken down 5. Opsin actives protein transducin 6. Transducing activities PDE (phosphodiesterase) 7. Brakes CGMP 8. Sodium and calcium can't enter to the rods 9. Rods come off 10. Retinal sensitivity decrease 11. Cons turn on 12. Visual acuity increase Can take 5-10 minutes to completely adjust. When we have to much brake the transducin leave the outer segment and enter the inner segment in the rods, the rods stop to function and the retinal sensitivity decrease. The cones start to help by constrict to focus light centrally on the macula lutea Light to dark adapation: 1. The pupil dilate-allow more light to reach the periphery of the retina where most of the rods are. 2. Rhodopsin accumulating- retinal sensitivity increases, rods trun on 3. Cons turn off- dark light is low wave length and the cons don't activated by this type of wave length. Visual acuity and color vision decrease. Can take 20-30 minutes Color blindness: X linked recessive disorder More common to men Lack of certain type of photopsins (the most common is not responding to red and green wave lengths of light) Nyctalopia/ night blindness: Decrease production/ intake of vitamin A. Less retinol production Decrease in photo pigments