P2 - 5.4 Eyes 1 - Structure of the Eye + Iris Reflex Flashcards
what is a cross section of something
where something is spilt in half so we can see the insides
when light first hits the eye what structure does it meet first
cornea
why is the cornea transparent
to let light through
True or False:
the cornea is not transparent
False it is transparent so it lets light through
does the cornea have blood vessels
no because it is transparent
True or False:
the cornea has no blood vessels
true
which way does oxygen diffuse at the cornea
from the outside into the cornea
why do we need the cornea
the cornea will bend/refract any light by a certain amount
what is the coloured bit of your eye called
iris
what colours can an iris be
blue, brown, green
what does the iris do
control how big or small your pupil is
what is the pupil
a gap in the middle of the iris that lets light pass through to the lens
what does the lens do
- it can change the shape of the light being refracted
- how strong the light being refracted is
- focuses light directly/perfectly onto retina
what 2 type of receptor cells can be found in the retina
cone cells (colours)
rod cells (black + white)
what do the cone cells do in the retina
detect colours in light
they aren’t very effective in low light
what do rod cells do in the retina
detect black and white light and are very sensitive
what are the main 5 structures of the eye
- cornea
- iris
- pupil
- lens
- retina
- fovea
- optic nerve
describe the pathway of light in the eye
light hits the cornea which refracts it through the pupil in the iris hitting the lens which then perfectly refracts it to the retina
what is the fovea
a special spot on the retina that is only full of cone cells (colour)
where do we try to focus light on in the retina so we can see clearly
on the fovea (where light refracting meets)
what is the optic nerve
the bit connected to the eye that takes all impulses generated by receptor cells to the brain
what is the iris reflex
when your eye changes the shape of your pupil to prevent your eyes getting damaged
Scenario:
You have looked at a bright light explain what happens to your eye
- constricted
- your circular muscles contract squeezing the pupil smaller
- radial muscles relax so they can be stretched longer
True or False:
bright lights can cause damage to your retina
true
Scenario:
You are in a dark room explain what happens to your eye
- dilated
- your circular muscles relax
- your radial muscles contract making them shorter and pulling the pupil open
what are the 2 different types of muscles that cause your eye to contract/dilate
inside = circular muscles
outside = radial muscles (stretch from inside to outside)
The eye is a sense organ. Which two stimuli are the receptor cells of the eye sensitive to?
- light
- colour
When the pupil is very large, do we describe it as ‘constricted’ or ‘dilated’?
dilated
When the pupil is very small, do we describe it as ‘constricted’ or ‘dilated’?
constricted
What happens to the circular and radial muscles when the pupil constricts?
- circular muscle contracts
- radial muscle relaxes
