eye Flashcards
What is the conjunctiva and its role?
Layer covering eye. Helps to lubricate it.
What is the lens and its role?
Transparent structure behind pupil. Helps to refract and focus light
What is the pupil and iris and their role?
Pupil- hole in centre of iris
Iris- lightened tissue.
Controls amount of light entering the eye
what is the job of the CNS
to coordinate a response
what does the CNS consist of
brain and spinal cord
order of the message
Recepotors detect stimulus
Send electrical impulses along sensory neutrons to the CNS
CNS send effector along a motor neurone
The effector then responds accordingly
what is a synapse
the connection between two neutrons
what are reflexes
responses that you don’t have to think about so they are quicker
what is the sclera
is the tough outer layer that protects the eye
what is the optic nerve
carries impulses form the receptors to the brain
what happens to the eye in bright light
triggers a reflex that makes the pupil smaller allowing less light in
what happens to the eye in dim light
in dim light the radial muscles contract which makes the pupil bigger
what happens when looking at distance muscles
the Hillary muscles relax which allows the suspensory ligaments to pull tight
this makes the lens go thin
so it refracts light by a smaller amount
to look at near objects
the ciliary muscles contract which slackens the suspensory ligaments
the lens becomes fat
this increases the amount by which it refracts light
what happens with short sighted people
cornea ir lens bends to much light so the imagine of distant objects are brought into focus in front of the retina
what happens with long sighted people
when the corn or lens doesnt bend the light enough. the objects are brought into focus behind the retina
