nervous system and eye Flashcards
What’s a stimulus?
-change in internal or external environment
what do the receptors do?
-detect stimuli
what do effectors do?
-produce a response to stimuli
describe the CNS process..
-receptors detect stimuli
-they send electrical impulses along sensory neurones to CNS
-CNS sends electrical impulses to the effector along motor neurone
why is the CNS quick?
-it has high speed electrical impulses
what are synapses?
-gap between 2 neurones
-nerve signal transmitted by neurotransmitters which diffuse across the synapse
what are reflexes?
-automatic responses to prevent injury
what is the eye an example of?
-sense organ
what does the conjuctiva do?
-lubricates and protects eye surface
what does the sclera do?
-tough outer layer that protects the eye
what does the cornea do?
-refracts light into the eye
-its transparent and has no blood vessels
what does the iris do?
-controls diameter of pupil
(how much light can enter)
what does the lens do?
-focuses light onto retina
what does the optic nerve do?
-carries impulses from receptors to brain
what happens to the eye when its dark?
-radial muscles contract
-pupils get bigger
