lesson 4 the structure of an eye Flashcards
as light hits the eye the first structure that it meets is what
the cornea
it allow all the light to pass through , meaning the cornea is what
transparent and has no blood vessels
why do we need the cornea
because it causes all the light that passes through it to refract
(Bend by a certain amount)
what is the iris
the coloured bit of your eye
the iris controls what
how big or small the pupil is
what is the pupil
a gap in the middle of the iris that allows the light to pass through the lens
what is the job of the lens
to refract light
(bend light)
what can the lens also do
change its shape
what does the lens changing shape do
allows it to control how strongly it refracts the light
the lens changing its shape helps what
helps it focus its light perfectly on the retina
where is the retina
at the back of th eye
what is the retina made up which 2 different type of receptor cells
cone cells
rod cells
cone cells are sensitive to what
the colour of light and allows us to see in colour
rod cells are what
more sensitive to light and only allow us to see in black or white
the fovea is what
a special spot on the retina which is full of only cone cells
fovea is the region we what
try and focus light on so we can see things more clearly
what does the optic nerve do
it takes all of the impulses generated by receptor cells and transmits them to the brain
when you look at bright light, the intensity of the light can do what
cause damage to your retina
how do you prevent damage to your retina from high light intensity
by iris reflex
what does iris reflex do
controls the size of your pupil
in high light intensity what happens to your pupil
(eg sun)
it gets smaller
in low light intensity what happens to your pupil
(eg moon)
it gets larger
when the pupils are small, what do we call it
constricted
when the pupils are large, what do we call it
dilated
to control the process of the iris reflex, the iris is made up of which 2 muscles
circular muscles
(around the inside of the iris)
radial muscles (around the outside of the iris)
what do circular muscles do inside of the iris
they stretch around the pupils like circles
what do radial muscles do inside the of the iris
the stretch from the inside to the outside
in order for iris reflex to occur what in depth happens to the two muscles
the circular muscles need to contract and the radial muscles need to relax
(vice versa for dark light)
