Biology 3 - Nervous system Flashcards
Purpose of iris
Alters size of pupil to control light that goes in
It’s a coloured muscle
What does the cornea do?
Allows light to enter and refracts it
What does the pupil do?
Allows light to enter
What does the lens do?
Changes shape to focus light onto retina
What does the choroid do?
Absorbs light to prevent reflection
What’s the retina?
Where the image is formed on the eye- impulses sent to optic nerve
Optic nerve?
Carries impulses from retina to brain
Blind spot?
Where the optic nerve leaves the eye- no light sensitive cells there
What’s the sclera on the eye?
The white bit- protects eye
What’s in the central nervous system?
Brain and spinal cord
How does information get passed from the receptors to the central nervous system?
Electrical impulses along neurones
Name the qualities of reflex actions
Protective, automatic and fast
Why do we blink
To protect the eye
Why does the pupil’s diameter change?
Protects the retina
Why do we pull away from things?
To prevent bodily harm
What’s the order of reflex actions? (7 stages)
- Stimulus
- Receptor
- Sensory neurone
- Co-ordinator (either brain or spinal cord)
- Motor neurone
- Effector (either muscle or gland)
- Response
What’s the gap between neurones called?
Synapse
