The Eye Flashcards
What is the role of the cornea?
Refracts the light that passes through it
What is the role of the iris?
Control the pupil size
What is the pupil and what does it do?
Gap in the middle of the iris that lets light through the lens
Why does the lens change shape?
Choose how strongly it focuses light on retina
What are the 2 different receptor cells on the retina?
Cone cells & Rod cells
Give two features of the cone cells
Sensitive to the colour of light
Not good in the dark
Give two features of the rod cells
More sensitive to light (used at night)
Only allow us to see in black and white
What is the role of the optic nerve?
Take impulses generated from receptor cells and transmit them to brain
What two muscles help change the shape of the iris
Circular and radial muscles
What happens to the pupil in bright light and why?
It constricts to limit damage to the retina
What happens to the pupil in low light and why?
It dilates to allow more light in and help you see in the dark
What is accommodation?
A reflex that changes the refractive power of the lens
What do the ciliary muscles and suspensory ligaments do?
Control the shape of the lens
What happens to the lens when you look at a close object?
It becomes short and fat so its more curved
How does the lens change shape to accommodate light from a nearby object?
Ciliary muscles contract inwards towards lens
Suspensory ligaments slacken so lens becomes fat
How does the lens change shape to accommodate light from a far object?
Ciliary muscles relax away from lens
Suspensory ligaments are pulled & tightened, stretching the lens out
What do convex lens help with?
Long-sightedness
What do concave lens help with?
Short-sightedness
