B1 The Nervous System

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What does your nervous system allow you to react to?
Your surrounding and coordinate your behaviour
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What does your nervous system compromise?
the central nervous system and the peripheral nervous system
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What does your CNS and PNS include?
receptors and neurones
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How do animals detect changes in their environments (stimuli)?
using receptors
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What are receptors?
Specialised nerve endings that generate nerve impulses
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Where are examples on your body of where receptors are?
light receptors in your eyes, sound receptors and balance receptors in your ears, taste receptors on your tongue, smell receptors in your nose, touch,pressure,pain and temperature receptors in your skin
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What are neurones?
(nerve cells) are specially adapted cells that can carry a nerve impulse.
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What are nerve impulses?
electrical messages/signals and are carried along the axon (the long, thin part of the cells)
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What are the three types of neurones?
sensory, relay and motor
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What do sensory neurones?
carry nerve impulses from the receptors to your brain
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What do relay neurones?
make connections between neurones inside your brain and your spinal cord
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What do motor neurones?
carry nerve impulses from your brain to your muscles and glands
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What are the three ways neurones are adapted to their job?
1. an elongated (long) shape (axon) to make connections from one part of the body to another 2. an insulating sheath to speed up the nerve impulse 3. dendrites (branched endings) to allow a single neurone to act on many muscle fibres
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An electrical impulse travels down a neurone until it reaches a?
synapse
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What is a synapse?
a small gap between neurones
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What diffuses across the synapse?
a transmitter substance
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What is caused when a transmitter binds with receptor molecules on the next neurone?
it causes an electrical impulse to be initiated in that neurone
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What is the chain involving synapses and neurones?
neurone A (electrical message) then synapse (chemical message) then neurone B (electrical neurone)
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What are voluntary actions?
actions that are under the conscious control of your brain
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What is an example of a voluntary actions?
tasting something bitter (stimulus) and then spitting it out (response)
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What are reflex actions?
actions that bypass the brain to give fast, automatic responses to a stimulus , to help protect your body from harm
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What are three examples of reflex actions?
1. pupil reflex automatically controls light entering your eye (to prevent damage to your retina 2. knee jerk reaction 3. withdrawing hand from a hot plate to stop it getting burned
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What is the reflex action pathway? (reflex arc)
stimulus to recpetor to sensory neurone to relay neurone (in spinal cord) to motor neurone to effector to response
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What is the coloured part of the eye?
the iris
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What does the iris do?
controls the amount of light that enters your eye
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What part of the eye refracts the rays of light?
cornea
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what does the lens focus the light onto?
the retina
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What does the retina contain?
light-sensitive receptors ( some are sensitive to colour)
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why does the lens focus the light onto the retina?
so that the rays converge at a single point and produce a clear image on your retina.
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What do the light-sensitive receptor cells on your retina then cause?
the nerve impulses to pass along sensory neurones in the optic nerve to your brain
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What is voluntary action pathway?
stimulus to receptor to sensory neurone to brain to motor neurone to effector to response
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What is the lens?
a clear, flexible bag of fluid
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what is the lens surrounded by?
circular ciliary muscles that change the shape of the lens
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What do the suspensory ligaments do?
attach the lens to the ciliary muscles
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What happens to the eye when receiving light from a near object?
the ciliary muscles contract, the suspensory ligaments relax and the lens is short and fat to refract llight
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What happens to the eye when receiving light from a near object?
the ciliary muscles contract, the suspensory ligaments relax and the lens is short and fat to refract llight a
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What happens to the eye when receiving light rays from a near object?
the ciliary muscles contract, the suspensory ligaments relax and the lens is short and fat to refract light a lot
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What happens to the eye when receiving light rays from a distant object?
the ciliary muscles relax, the suspensory muscles contract and the lens is long and thin because the light only needs to be refracted a little
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Other cards in this set

Card 2

Front

What does your nervous system compromise?

Back

the central nervous system and the peripheral nervous system

Card 3

Front

What does your CNS and PNS include?

Back

Preview of the front of card 3

Card 4

Front

How do animals detect changes in their environments (stimuli)?

Back

Preview of the front of card 4

Card 5

Front

What are receptors?

Back

Preview of the front of card 5
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