Nervous System - Visual and Hearing Senses Flashcards
protective structures of the eye (5)
- bony orbit
- eyebrows
- eyelids
- eyelashes
- lacrimal apparatus
lacrimal apparatus
- lacrimal gland secretes tears which flow through ducts and drain through nasolacrimal duct
conjunctivitis / pink eye
inflammation or infection of eye
- vasodilation causes pink colour
structure of eye
- fibrous: outer layer
- vascular (uvea): middle layer
- nervous: inner layer
parts of fibrous, vascular, and nervous layers
- sclera, cornea
- choroid, ciliary body, iris
- retina
fluid compartments of the eye
- partition - ciliary body (processes, muscle), suspensory ligaments, lens
- aqueous humour and vitreous humor - support the internal pressure, help maintain eye’s shape and size
three sequential processes of visual perception
- focus light on retina
- transduce the light to a nervous signal
- process the nervous signals to form conscious perception of objects
refraction
bending of light rays
snell’s law of refraction *
(n1)sin(X1) = (n2)sin(X2) n = refractive index of mediums X = angle formed by incident light ray and a line perpendicular to surface of medium
convex lens
converging rays
concave lens
diverging rays
focal point (F)
- single point on axis where incident rays of light converge
- measure of the refractive power of a lens
focal length (f)
- distance from the lens to the focal point
- measure of the refractive power of a lens
refractive power [diopters]
- inverse of focal length
- measure of how much light is bent en route to the retina
accommodation of the eye
- light from close objects must be bent more; the lens rounds up to do this
near point
nearest an object can be and still be clearly seen
power of accommodation
difference in the refractive power of the relaxed eye and the maximally accommodated eye
presbyopia
eye’s natural lenses lose their flexibility as part of the normal aging processes
- hard to see :(
emmetropia
eye that has no visual defects
optic disk
region where optic nerve leaves the eye