Nervous system pt.2 Flashcards
what is the eye protected by
Bony eye socket
Eyelids and eyelashes
eyebrows
the eye is held in place by?
6 muscles
conjunctiva function?
contains pain receptors
sclera function
the white part of the eye. it gives shape to the eye
cornea function
transparent(so light can pass through) layer that is responsible for the refraction of light rays
what is the Iris?
the colour part of the eye and forms the pupil. contains muscles that contact or relax to change the size of the pupil
Pupil function
black centre of the eye.
controls amount of light entering the eye
lens function
transparent, bi-convex disc that focuses light rays on the retina
Retina function
contains photoreceptors that convert light into electrical impulses
name the two photoreceptors and it’s functions?
Rods - allow us to see in dim light. black and white
Cones - allow us to see in bright light and in colour
function of the optic nerve?
sends impulses to the cerebrum to be interpreted as an image
function of choroid?
contains blood vessels which supply nutrients and oxygen
how do we see?
- object reflects light
- light enters the eye and is refracted by the cornea then the aqueous humour then the lens then the vitreous humour
- focused on the yellow spot on retina
- photoreceptors convert light rays into electrical impulses
- optic nerve takes impulse to occipital lobe of the cerebrum
- cerebrum interprets impulse as an image
explain blindness
lack of vision which can not be corrected by glasses. can be caused by accidents (injure surface of the eye) or diseases (diabetes)
what is myopia
short sightedness/nearsightedness
can only see close objects clearly (closer than 6m)
what is hyperopia
farsightedness
can only see distant objects clearly (further than 6m)
what is astigmatism?
where the cornea is irregularly shaped and the light rays are not evenly refracted. causes blurry vision.
