eyes Flashcards
what is the sclera
white part of the eye
-keeps the shape of the eye
-fibrons and tough
what is the cornea
-transparent window at the front of the eye
-lets light into the eye and refracts it
what is the iris
-coloured part of the eye
-made of muscles that control the shape/size of the pupil
what is the pupil
-whole in the middle of eye
-lets light in and reach the retina
what is the choroid
-dark pigmented layer
-prevents light from being reflected around the eye
-contains blood vessels
what is the retina
–innermost layers the eye
-contains loads of cone and rod receptor cell
what are the rod cells
-a receptor cell that reacts to light and produces impulses to the sensory neurones
-helps to see in black and white
what are cone cells
a receptor cell that reacts to light and produces impulses to the sensory neurones that makes you see in colour
what does the optic nerve do
-carries impulses from the receptors to the brain
what is the fovea
where cone cells are particularly concentrated
what is refraction
when light bends once it hits the eye
what is the blind spot
-where the optic nerve leaves the eye
-so there are no rod or cone cells
-where the vision isn’t very sharp
accommodation- distant object
-moves the lens backwards and forwards until the picture is sharp
-light rays are almost parallel when they reach the cornea which refracts the rays
accommodation- near object
-the ciliary muscles contract, the suspensory ligaments become slack, elastic lens bulges outwards into a more convex shape
how does the pupil respond to dim light
-circular muscles relax
-radial muscles contract
-pupils dialate
