The Eye Flashcards
Iris function
Controls size and shape of pupil
Pupil function
Shape determines the amount of light entering the eye
Lend function
Focus light onto retina - adjusts shape to change refractive index
Cilliary muscles function
Controls lens size
What is accommodation?
When the eye can focus on objects at different distances
How does a lens adapt to see a near object?
Tenses - lens thicker - power increases
How does a lens adapt to see a far object?
Relaxes - lens thinner - power decreases
Choroid function
Supply oxygen to eye (blood vessels)
Fovea function
Sharpest image created when light focuses on this area - due to high concentration of cones
Retina function
Light sensitive layer of cells that is focuses on by the lens
Optic nerve function
Transmits image in the form of electrical signals to brain
Blind spot function
No retina at this point due i optical nerve - so no image formed in this area
Aqueous humour function
Watery, clear liquid that allows light to reach retina - low refractive index
Vitreous humour function
Black liquid keeps eye’s shape
Cornea function
Focus light as it has high refractive index
What is more common in the eye? rods or cone cells
Rods - 20x more common
What cells are used in low levels of light?
Rods
What cells are used in high intensity light?
Cones
Why are colour images more detailed?
Incorporate more wavelengths to differentiate between
Why do rods see in low detail?
Several rod cells are joined by one nerve, this blurts the image formed
What wavelength of light do cones absorb least well?
Blue
What is persistence of vision?
When an image remains, even when the bright/intense stimulus remains
Why do flickering lights above 5Hz appear as one light?
Cones take a few seconds to return to normal sensitivity. So the cones can’t desensitise in the time in between flickers
