Describe the sclera and its function
The white part of the eye. (opaque and tough)
function: shape and protection
Describe the cornea and its function.
The transparent part of the sclera at the front of the eye.
Let's light in and bends it towards the retina
Describe the Conjunctiva and its function
Transparent membrane protecting the cornea
Describe the Choroid and its functions
contains the blood capillaries to nourish the eye and melanin (black pigment) to absorb light (no internal reflection of light)
Describe the retina and its function
the innermost layer containing the light receptors (rods and cones)
Describe the rods
contain rhodopsin (vitamin A required to form it)
detect black and white
work in dim light
found all over retina
Describe the cones
Have 3 pigments that detect blue, red and green
found mostly in the fovea
work in bright light
the area where the optic nerve leaves the eyeball
contains no visual receptors
Fovea (yellow spot)
opposite the centre of the pupil
contains cones only. Regions of sharpest vision, most images are formed here
Carries impulses from the retina to the brain.
coloured part of the eye. Controls size of pupil and amount of light entering the eye (reflex action).
Its circular muscle contract to narrow the pupil in bright light to reduce the amount of light and its radical muscles contact to widen the pupil in dim light enters the eye
opening in the iris through which light enters.
biconvex, transparent and elastic, changes shape to focus light on to the retina. Contains a clear protein which can become cloudy (cataracts).
changes shape of the lens
Attaches the ciliary body to the lens.
A watery liquid between cornea and lens, made in ciliary body-maintains eye shape; nourishes cornea and lens (these don't have their own blood supply) and helps to refract light.
A jelly-like substance between lens retina, gives shape to the eye
changing the shape of the lens to focus near and distant objects