B3.1.3 - The Eye Flashcards
What is the eye?
The sense organ that allows you to see
Name the main structures of the eye.
Cornea, pupil, iris, lens, ciliary body, suspensory ligaments and optic nerve
Describe the cornea and its function.
A transparent coating on the front of the eye which protects the eye and refracts light entering the eye
Describe the iris and its function.
A coloured ring of muscle tissue which alters pupil size by contracting or relaxing
Describe the pupil and its function.
A central hole in the iris which allows light to enter the eye.
Describe the lens and its function.
Transparent biconcave lens which focus light clearly onto the retina.
Describe the ciliary body and its function.
A ring of muscle tissue which alters the shape of the lens
Describe the suspensory ligaments and its functions.
Ligament tissue which connects the ciliary muscle to the lens
Describe the optic nerve and its function
Nervous tissue which carries nerve impulses to the brain
How are images formed on the retina?
The cornea refracts incoming light rays which provides most of the focus to the incoming light, which passes through the pupil and is then further refracted by the lens, creating a sharp image on the retina.
What is meant by the term ‘refracts’?
Changes the direction of
What happens after a sharp image is on the retina?
Photoreceptors produce a nervous impulse due to the exposure of light which travels down the optic nerve to the brain, which interprets the impulses as a visual image.
What are photoreceptors
Light sensitive cells in the retina
What happens to the lens when your ciliary muscle contracts?
It becomes more convex (can focus on nearby objects)
What happens to the lens when your ciliary muscle relaxes?
It becomes less convex (can focus on distant objects)
