Visual System Flashcards
how many rod cells in the retina
90 million
how many cone cells in the human eye
10 million colors
where are the cones and rods housed
in the neural retina
lens function
focuses visual images onto retina
iris function
circular membrane that controls amount of light entering eye
parasympathetic eye
pupillary constriction
sympathetic eye
pupillary dilation
lens is flatter with…
far vision
near vision
ciliary muscles contract- causes lens to become more convex
optic disk
blind spot where blood vessels and optic nerve fibers enter
fovea
where we have our best vision. in middle of cornea, narrow cones only
rods
sensitive to light
responsible for vision in low light conditions
action stream
a stream of visual info that flows dorsally and used to direct movement
perception stream
a stream of visual info that flows ventrally and used to recognize visual objects
conjugate eye movements
both eyes move in same direction
vergence eye movement
eye moves toward the midline or away from the midline
vestibular occular reflex
action of vestibular info or the eye position during fast movements of the head
optokinetic reflex
use of visual info to stabilize images during slow movements of the head
adjust eye position during slower head movements
saccades
fast eye movement to switch gaze from one object to another
smooth pursuit
eye movements that follow a moving object
ex. watching someone walk across a room
vergence movements
movement of the eyes toward or away from midline to adjust for different differences between the eyes and the visual target
