PSYC 212 Chapter Notes -Stray Light, Ganglion Cell, Rhodopsin
20 Mar 2013
School
Department
Course
Professor
Document Summary
Retina: net-like, thin film of cells lining inside back wall of eye. Image is projected on outer margins of retina, where there are photoreceptors. They are the transducers convert light energy into signals. Those signals are then processed by other neurons in the retina. These cells absorb stray light that photoreceptors don"t catch. If stray light isn"t absorbed it can interfere with normal processing of vision. Optic disk: point in retina where nerve fibres converge to exit eyeball. Opposite with rods: more numerous in periphery and less so in centre. Large concentration of cones in fovea is dedicated to processing image detail (in light conditions) Photopigments concentrated in outer segment of photoreceptors (embedded within fibrous matrix) Dark current: inward flow of sodium (that bind to cgmp) in rhodopsin in the absence of light. Balanced out by outward flow of k ions in inner segment. Sodium potassium pump reverses this so there isn"t excess buildup.
