Topic 5 The Eye Flashcards
What is the sclera
The tough outer wall that supports the eye
What is the cornea
The transparent outer layer at the front of the eye
What does the cornea do
Refracts and bends light into the eye
What is the iris and what does it control
Contains muscle that allows it to control the diameter of the pupil (hole in the middle of the eye) and therefore how much light enters the eye
What is the lens and what does it do
Focuses light onto the retina
What is the Retina
At the back if the eye and contains receptor cells sensitive to light and colour
What is the shape of the lens controlled by
Ciliary muscles and suspensory ligaments
What attaches the lens to the outside of the eye
The suspensory ligament attaches the lens to the ciliary muscles which is joined to the sclera
What does the optic nerve do
Carries impulses from the receptors on the retina to the brain
What is the iris reflex
When it adjusts for bright light
What causes iris reflex
When light receptors in the eye detect a bright light the circular muscles in the iris contract and the radial muscles relax making the pupil smaller and allowing less light into the eye
What happens to the pupil when lights is dim
The radial muscles contract whilst the circular muscles relax and the pupil becomes wider
What is accommodation
When the eye focuses light on the retina by changing the shape of the lens
How does the eye accommodate to look at near objects
Ciliary muscles contract which slackens the suspensory ligaments
Lens becomes fat (more curved) which increases the amount by which the light is refracted
How does the eye accommodate to look at distant objects
The ciliary muscles read which allows the suspensory ligaments to pull tight
Makes the lens thin (less curved)
So it refracts light by a smaller amount
