eye Flashcards
what do cones detect`
colour
what do rod cells detect
colour
what can’t cones do?
work in dark environments
what cant rods do?
see in colour, they can only detect black and white.
what is tje fovea?
an area which only has cone cells, where light is focussed on to see properly.
what is the cornea?
transparent layer that refracts light.
does the cornea have any blood cells
no
where does the cornea get oxygen from
it diffuses from the air
what is the iris?
coloured part of the eye that controls how much light enters
what is the lens?
can change shape to change the way it bends light
what is the retina?
contains rod and cone (receptor) cells
what is the optic nerve?
takes all impulses generated from receptor cells and sends them to the brain
what is the iris reflex?
it controls light intensity
what does the iris reflex protect us from
retina damage from too much light.
what are the iris reflex actions controlled by
the circular and radial muscles
name of the shrunken pupil
constriction
name of the widened pupil
dialated
when are pupils constricted
in high light conditions
when are pupils dialated
in low light conditions
where are the circular muscles situated?
in the inside, stretching around the pupil
where are the radial muscles situated
on the outside, stretching around the circular muscles
what happens to the eye muscles when the pupil is constricted
- circular muscles contract, tightening the pupil so its smaller,
- radial muscles relax, stretching out so that the pupil stays small
what happens to the eye muscles when the pupil is dialated
- circular muscles relax, allowing the pupil to stretch
- radial muscles contract, stretching the pupil to let more light in
what is accommodation
changing the shape of the lens to focus on near or distant objects
what parts of the eye control the shape of the lens
suspensory ligaments and ciliary muscles
shape of lens while refracting a close object
short and fat so that it refracts stronger
what do the ciliary muscles and suspensory ligaments do when a object is near
- ciliary muscles contract inwards
- suspensory ligaments relax so lens becomes short and fat
shape of lens while refracting a far object
thin and stretched
what do the ciliary muscles and suspensory ligaments do when an object is far
- ciliary muscles relax to thin out lens
- suspensory ligaments are pulled to stretch out lens and refract light less intensely
what is the name for when the lens doesn’t refract enough
hyperopia (long sightedness)
what additional lenses are used for myopia
concave lenses
what is the name for when the lens refracts too much light
myopia (short sightedness)
what additional lenses are used for hyperopia
convex lenses
