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Biology GCSE
Response and regulation (2.5)
The nervous system
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Cards (27)
What does the human nervous system consist of?
The
central nervous system
(CNS) and the
peripheral nervous system.
What is in the central nervous system? (CNS)
The
brain
and the
spinal cord
What is the peripheral nervous system?
Nerve
cells
that carry
information
to and from the
CNS
What are nerves?
Bundles of neurones.
What are neurones?
Long
cells which carry
electrical
impulse
signals.
What is a
synapse
?
A
gap
where
2 neurones
meet.
How are electrical impulses passed?
Chemically.
What are sense organs?
Group of receptor cells
(
specialised
) which produce
electrical
impulses.
What is the stimulus for skin?
Temperature
,
pressure
and
pain.
What is the stimulus for tongue?
Chemicals in the mouth.
What is the stimulus for nose?
Chemicals in the air.
What is the stimulus for eye?
Light.
What is the stimulus for ear?
Sound.
What are
effectors
?
Parts of the body, like
glands
/
muscles
which
produce a
response
to a detected
stimulus.
What are 3 examples of effectors?
A muscle
contracting
to move an
arm
A muscle
contracting
to alter
pupil size
a gland
releasing
a
hormone
into the
blood.
What are the main stages in a reflex arc?
Stimulus
Receptor cells
Electrical impulse along sensory neurone
Synapse
Relay neurone
Synapse
Motor neurone
Effector
Response
What is a
reflex action
?
Usually protective, involuntary and fast.
What doesn’t a reflex response need?
The
brain-
instead the
spinal cord coordinates
the
response
so that the
electrical impulse
can reach the
effector quickly
How is light entering the eye controlled?
By a
reflex
response through the
muscles
in the
Iris.
It changes in response to
bright
or
dim
light
What does the cornea?
Clear part of sclera
,
refracts light
What does the lens do?
Focuses light onto
the
retina
What does the
optic nerve do
?
Carries impulses
between
retina
and the
brain
What is the sclera?
White
,
tough
,
protective layer
What does the choroid do?
Pigmented
middle layer,
absorbs
light to avoid
reflection
What is The blind spot?
Where the
optic nerve
leaves the
retina
and lacks
receptor cells
What is the pupil?
A small
hole
at the
centre
of the
iris,
where
light
enters
eye
How
might reaction time be affected?
Age
and if the person has had
stimulants
(e.g caffeine)