Eye Flashcards
What is the cornea and where is it located?
It is the bulged part of the sclera. It is tough and transparent.
It is the outer-most part of the eye apart from the conjunctiva.
What is the function of the cornea?
Refracts light and bends it as it enters the eye
What is the iris and where is it located?
A pigmented section, so that light can’t pass through it.
It has the pupil in the middle of it, and the lens behind the pupil.
What is the function of the iris?
Its muscles contract and relax to change the size of the pupil.
This controls the amount of light entering the pupil.
What is the lens and where was it located?
It is a transparent, flexible disc behind the iris.
It is attached to the ciliary muscles by the suspensory ligaments.
What is the function of the lens?
It focuses light onto the retina
What is the retina and where is it located?
It is the lining of the back of the eye, which contains two types of photoreceptor cells, rods (black and white) and cones (colour)
What is the function of the retina?
It contains light receptors
What is the optic nerve and where is it located?
It is a bundle of sensory neurones at the back of the eye
What is the function of the optic nerve?
It carries impulses from the eye to the brain
What is the fovea and where is it located?
It is a small area in the middle of the retina that contains many more cones than rods
What is Myopia?
Short-sightedness
What is Hypermetropia?
Long-sightedness
How is Mytopia caused?
When the lens focuses the sharpest image in front of the retina (short-sight)
How is Hypermetropia caused?
When the lens focuses the sharpest image behind the retina (long-sight)
What is the aqueous humour and what does it do?
It is a transparent watery fluid located in the front of the eye (between the lens and the cornea)
It maintains the shape of the eyeball
What is the vitreous humour and what does it do?
It is the transparent jelly which fills the large space behind the lens.
It holds the lens and retina in place and it helps bend light
What is the ciliary muscle and what does it do?
It is a ring of muscle which is attached to the lens by the suspensory ligaments.
It changes the thickness of the lens so light rays can be focused on the retina.
What happens when the ciliary muscle contracts?
The suspensory ligaments slacken and the lens thickens
What happens when the ciliary muscle relaxes?
The suspensory ligaments pull on the lens and the lens becomes thinner
What is the choroid layer?
It is the thin black middle layer which contains the main blood vessels and blood supply to the eye.
Its black pigment prevents reflection of light within the eyeball.
What is the sclera?
It is the tough, white outer layer which protects the delicate parts in the eye
What is the function of the suspensory ligaments?
They hold the lens in place and change the shape of the lens in conjunction with the ciliary muscle
Where is the blind spot?
The point at which the optic nerve leaves the eye
What happens to the eye when exposed to bright light?
The radial muscles of the iris relax
The circular muscles contract
Less light enters the eye through the contracted (smaller) pupil
What happens to the eye when exposed to less/dim light?
The radial muscles of the iris contract
The circular muscles relax
More light enters the eye through the dilated (larger) pupil
