2j - coordination and response Flashcards
what are the three type of neurone?
- sensory neurone
- relay neurone
- motor neurone
what does the sensory neurone do?
receives sensory info and carries nerve impulses from the receptor cell towards the CNS
what does the relay neurone do? where is it?
makes connections between sensory neurones and motor neurones. found in the CNS
what does the motor neurone do?
receives sensory info from a relay neurone in the CNS and carries nerve impulses to muscles and glands
what is a stimulus?
a change in the surroundings
what is a receptor?
an organ or cell detecting a stimulus
what is an effector?
a muscle or gland
what is a response?
a reaction to change
what is the CNS?
the central nervous system
what is a reflex arc?
when the relay neurone carries the impulse to the motor neurone rather than the brain to avoid damage
why is the response in a reflex arc so fast?
because the message doesn’t go to the brain
what is a reflex?
an action that is performed without conscious thought as a response to a stimulus
what is the fovea?
the most sensitive part of the eye, with the highest density of cone cells
what is the blind spot?
the area of the eye where the nerves join together, it doesn’t contain any light sensitive cells
which cell (cone cells/rod cells) send info about colour
cone cells
when are rod cells more sensitive?
at low light conditions
what does the lens do?
focuses light onto the retina
what does the iris do?
controls how much light enters the pupil
what does the cornea do?
bends (refracts) light entering the eye
what does the optic nerve do?
carries impulses to the brain
what does the retina do?
contains light receptors
why are the rays of light refracted by the cornea and lens?
so that they converge at a single point to produce a clear image
what is the vitreous humor?
the liquid in the eye that keeps its shape
what happens when you focus on a near object?
the ciliary muscles contract, the suspensory ligament therefore lose tension
