Sight Flashcards
What is the conjunctiva?
A thin membrane protecting the sclera
What is inflammation of the conjunctiva called?
Conjunctivitis
What is conjunctivitis?
Inflammation of the conjunctiva
What is the sclera?
The white of the eye
What is the sclera also called?
The sclerotic coat
What is the function of the sclera?
2 points
It lets no light through as it is very tough and opaque
It holds the eye in shape
What is the choroid?
A dark-coloured layer which contains blood vessels which nourishes the eye and melanin which absorbs light in the eye
What is the function of the choroid?
Ensures that there is no internal reflection of light inside the eye.
What is the function of the retina?
Contains light receptors (cones/rods)
How many rods are found in the eye?
120 million per eye
How many cones are found in the eye?
6 million per eye
What is the function of rods?
Detects black and white light
What is the function of cones?
Detects colours
What type of light do rods work in?
Dim light
What type of light do cones work in?
Bright light
Where are rods found in the retina?
All over the retina
Where are cones found in the retina?
Mostly at the fovea
What is the fovea?
3 points
The are of the retina where only cones are found
It is the region of sharpest vision
Most images are focused here
What is the fovea also called?
The yellow spot
What is the blind spot?
4 points
A part of the retina where nerve fibres leave the eye
There are no cones or rods found here.
It is not sensitive to light
The area of the eye where vision is obstructed due to nerve fibres of rods and cones impeding incoming light rays
What is the optic nerve?
The area of the eye where 126 million axons are found which carry impulses from the rods and cones to the cerebrum
What is the lens?
An elastic, transparent structure which changes shape to focus light on the retina.
What is the ciliary muscle?
Muscle which surrounds the lens
Causes the shape of the lens to change when looking far away or close
What is the changing of the shape of the lens called?
accommodation
What connects the ciliary muscle to the lens?
Suspensory ligaments
What is the iris?
The coloured, muscular part of the eye which controls the amount of light entering the eye
May be pigmented with melanin (eye colour)
What is the pupil?
The opening in the iris which lets light into the eye
It is black as no light emerges from the inside of the eye
What happens to the size of the pupil in bright light?
Its size reduces to let less light enter the eye
What happens to the size of the pupil in dim light?
Its size increases to let more light enter the eye.
What is the aqueous humour?
A salt solution which holds the front of the eye in place
What is the vitreous humour?
A viscous solution which supports the eye by exerting an outward pressure on the eyeball
What are the external muscles?
Six muscles which control the movement of the eye
