B10 - The Eye Flashcards
Sclera
The white outer layer which protects the eye.
Cornea
Front part of the tough outer coat (Sclera). It is convex and transparent to refract light as it enters the eye.
Aqueous humour
Liquid between Iris and Cornea which gives the eye it’s shape.
Iris
Muscular, coloured disc that contracts and relaxes to change the size of the pupil, controlling the amount of light which can enter the pupil.
Pupil
A hole in the Iris which allows light to enter the eye.
Lens
Transparent, bi-concave, flexible disc behind the iris which focuses light onto the retina.
Suspensory ligament
Attaches the lens to the ciliary muscles.
Ciliary muscles
Muscles which surround the lens to change it’s shape when accommodating to close/far objects.
Vitreous humour
Jelly-like substance between the lens and the retina which gives the eyeball it’s shape.
Retina
Light sensitive region at the back of the eye which convert’s light to electrical impulses.
Optic nerve
Bundle of sensory neurones at the back of the eye which carries impulses from the eye to the brain.
Blind spot
The point where the optic nerve leaves the eye, where there are no light receptors to process images.
What happens to the eye in Bright light?
Circular muscles contract
Radial muscles relax
Pupil constricts to let less light enter the eye
What happens to the eye in Dim light?
Circular muscles relax
Radial muscles contract
Pupil dilates to let more light enter the eye
What happens when the eye focuses on a distant object?
Light enters as parallel rays
Ciliary muscle relaxes
Suspensory ligament pulled tight
Lens pulled flat and thin to only slightly refract light onto the retina.
