Chapter 6 eyes 2 Flashcards
What is inside the eye?
Inside the eye is fluid
why is there fluid inside the eye?
the fluid supports the eye so it doesn’t collapse inwards and it provides nutrients to the cornea which has no blood vessles
What does the fluid behind the lens do?
the fluid behind the lens supports the lens and gives shape to the eye
What does the cornea do?
the cornea refracts incoming light so it converges towards the retina
What does the lens do?
the lens fine tunes the focus from the cornea
what controls the lens?
small muscles control the lens so it can change shape to help focus
To see near objects what does your lens have to do?
to see near objects your lens has to be thicker, so there is more muscle (contraction) in the eye but less tension on the lens
To see far objects what does your lens need to do?
to see far objects your lens has to be thinner, so the muscles relax, which increases tension on the lens making it thinner
What is weird about the way light gets to the back of the eye?
Light from the bottom of an object goes to the top of the retina, light from the top of an object ends up at the bottom of the retina, so the image is inverted or upside down
What provides most of the focussing done by our eyes?
the cornea does most of the focussing for the eye
What does the remainder of focussing after the cornea has done its job?
the lens does the remainder of the focussing.
What is the area where the optic nerve enters the retina called?
the blind spot b/c there are not rods or cones there
what are the cells that absorb light called?
rods and cones
what is the difference between rods and cones?
their shape is different: rods are cylindrical; cones are rounder
What do rod cells do?
they are the black and white vision system, sensing shades of light and dark (and movement but they can see colour – not green well –we just don’t use them for that)
