Eye Flashcards
draw a diagram of the internal structure of an eye
see diagram in manual
structure of the sclera
- outer layer of the eye which is opaque
- forms cornea at the front of the eye
function of the sclera
-protection and gives shape to the eyeball
structure of the choroid
-dark black middle layer with melanin
function of the choroid
prevents internal reflection
-i.e. absorbs any light rays that may pass beyond the retina
structure of the retina
-innermost layer of the eye with rods and cones which are photoreceptors
function of the retina
converts light into nerve impulses so an image forms on the retina
-basically generates impulses
structure of the fovea
-part of the retina with cones only
function of the fovea
-gives detailed coloured vision in bright light
structure of photoreceptors
- they are sensory cells sensitive to light
- called rods and cones
- rods contain the pigment rhodospin which need vitamin A to manufacture
function of photoreceptors
- rods provide vision in dim light, but detail is in black, white and grey
- cones give coloured vision in bright light
structure of cornea
-is the transparent front of the eye with a curved surface so it can focus light rays
function of the cornea
allows light to enter the eye and bends it toward the retina
structure of the aqueous humour
-clear liquid with salt
function of the aqueous humour
supplies nutrients and oxygen to the cornea and maintains the shape of the cornea
structure of the vitreous humour
clear and gel like
function of the vitreous humour
maintains the correct shape of the eyeball
structure of the pupil
the pupil is the central opening of the iris
function of the pupil
is to allow light to enter the eye:
-dilates (widens) is dim light to allow more light to enter the eye
-constricts (gets narrower again) so less light enters and avoids the dazzling effect
structure of the iris
-coloured sheath of muscle with melanin
what does the iris determine
the iris determines the diameter of the pupil
what is the function of the iris
> iris controls the amount of light entering the eye as follows
- iris contracts
- in response to changing light intensity
- therefore changing the size of the pupil so more or less light enters the eye
what is the structure of the lens
lens is transparent with a curved surface
biconcave in shape
function of the lens
lens focuses light on the retina and carries out fine adjustments to produce sharp image
structure of the suspensory ligaments
fibres which connect the the ciliary body to the lens
function of the suspensory ligaments
the suspensory ligaments holds the lens in position and are involved in changing the shape of the lens
structure of the ciliary body
the ciliary body is a ring of choroid tissue which contains the ciliary muscle
function of the ciliary body
the ciliary body secretes the fluid that forms the aqueous humour
function of the ciliary body
the ciliary body secretes the fluid which forms the aqueous humour
function of the ciliary muscle
the ciliary muscle controls the curvature and focusing strength of the lens
structure of the blind spot
part of the retina
function of the blind spot
does not generate a visual response as theres no rods and cones here
structure of the optic nerve
bundles of nerve fibres
function of the optic nerve
the optic nerve carries impulses to the cerebrum of the brain
