Topic 2 (the eye) Flashcards
What does the cornea and the lens do?
They both reflect light which helps focus on the retina
What does the iris do?
It controls how much light enters the pupil
What is the retina and what is it covered in?
It is light sensitive and it’s covered in receptor cells called rods and cones
What does the rod function in?
It is sensitive to dim light but can’t see colour ( different light intensity)
What is the function of cone cells?
There are sensitive to different colours but do not work in dim lights
How is the information delivered?
The light is converted intellectual impulses then the optic nerve carries the impulses from the receptor to the brain
What happens to the lens when you focus on it or distant objects?
The lens is elastic so that I can focus onto the retina by changing the shape of the lens
What happens to the lens when you look at the distant object?
The ciliary muscle relaxes and the suspensory ligaments pull tight, this pulls the lens into less rounded shape so the light is less refracted
What happens to the lens when you look at a close object?
The ciliary muscle contracts and the suspensefully ligaments slacken causing the lens to a become more rounded shape and so the light is refracted more
Why can someone be longsighted?
They are unable to focus on near objects which occurs when the lens is the wrong shape or doesn’t bend the light enough or the eyeball is too short, this causes near objects to be brought into focus behind the retina, you can use glasses or contact lenses with convex lenses to correct it.
Why can someone be shortsighted?
There are unable to focus on distant objects this occurs when the lens is the wrong shape and bends the light too much or the eyeball too long.
This causes the distant object to be brought into focus in front of the retina.
You can use glasses or contact lenses with a concave lens to correct it.
Why does colour blindness happen?
Most common disorder is red and green colour blindness.
It is caused when the red green cones and the retinal are not working properly but there’s no cure for colour blindness because the cone cells can’t be replaced
What is cataracts and what happens to the lens?
Cataract is the buildup of protein on the lens which causes the light to stop entering the eye which causes people to have blurred vision and so they experience less vivid and difficulty seeing in bright light.
cataracts can be treated by replacing the faulty lens with an artificial one through surgery.
What happens to the iris in very bright lights?
The circular muscles contract and the radial muscles relax, making the pupil smaller.
What happened to Iris in dim lights?
The circular muscles relax and the radial muscles contract, making the pupil larger.
