B1d - The Nervous System Flashcards
What does the pupil do?
Lets light in to the eye.
What does the lens do?
Refracts the light; focuses the light onto the retina.
What does the cornea do?
Refracts the light.
What does the iris do?
Controls how much light can enter through the pupil.
What does the retina do?
Contains light receptors
What does the ciliary muscle do?
Contracts and relaxes to change the shape of the lens.
Where is the blind spot?
Whee the optic nerve meets the retina.
What is the definition of accommodation?
How the eye focuses light by changing the shape of the lens.
What is the difference between monocular and binocular vision?
Binocular vision - eyes on the front of the head, good at judging distance but smaller total area of vision.
Monocular - eyes at the sight of the head, bad at judging distance but larger total area of vision.
If the eye is looking at a near object, describe the
- shape of the lens
- ciliary muscle
- suspensory ligament
- how much the light bends
The shape of the lens is rounded, the ciliary muscle is contracted, the suspensory ligament is loose, and the light bends more.
If someone is long sighted, why can’t they see close objects well?
Because the light does not bend enough, so the rays still haven’t met when they reach the retina.
What are the stages of a reflex action?
Stimulus -> receptor -> sensory
neurone -> CNS -> motor neurone ->
effector -> response
What is a synapse?
A junction between two neurones.
How does a synapse work?
When an impulse reaches the end of a neurone, it triggers the release or a neurotransmitter, which diffuses across the synapse. It then binds on to a receptor on the next neurone causing the impulse to continue.
