The Eye Flashcards
explain why the eye would be considered a receptor organ
it senses stimuli and converts this to a nerve impulse and is then transmitted via the CNS to the brain where its interpreted
why is it necessary to have 2 eyes
for the perception of death
name the 2 photoreceptor cells
rods and cones
explain the difference between rods and cones
rods - black and white vision
cones- colour vision
explain what happens after light strikes the retina
the photoreceptor cells are stimulated
nerve impulses are sent via the optic nerves to cerebrum of brain where an image is formed
name the area of clearest vision of the eye
fovea/ yellow spot
what is the name of the membrane that protects the eye
the conjuncitiva
what is the function of the fluid secreted by the tear gland
keeps conjunctive moist
has enzymes which kill bacteria.
what are the 3 functions of the eye
accomodation
pupilary mechanism
binocular vision
explain the process that occurs in the eye during near vision
ciliary muslces contract suspensary ligaments contract tension of lens decreases lens becomes more convex and rounded refractive power of lens increases focal length decreases.
explain the process that occurs in the eye during far vision
cilary muslces relax suspensory muscles become taut tension on lens increases lens is made longer and thinner decreases refractive power of lens focal length increases
explain process that occurs in the eye when exposed to bright light.
circular muscles contract
pupil constricts
radial muscles relax
less light is allowed into eye
explain process that occurs in the eye when exposed to dull light
circular muslces relax
radial muslces contract
more light allowed in
what does binocular vision allow
allows person to estimate size, distance, depth.
state the pathway of light into the eye
cornea - aqueous - humour - pupil - lens - vitreous humour - retina
what is the causes of myopia
eyeball is too long
how to fix myopia
concave lens needed
what is the cause of hyperopia
eyeball too short
how to fix hyperopia
convex lens needed
cause of astigmatism
cornea or lens with unequal curvature
how will someone know if they have an astigmatism
only part of an image is clear
what is a cataract
lens becomes cloudy and it impacts vision
name the 3 group of people who will be at most risk for getting cataracts
diabetics, high BP, elderley
what is the scleriotic layer
tough, white, protective layer that surrounds the eye to maintain shape
