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Unit 3, Key Area 3: What you should know
1. The nervous system is composed of sensory, inter and motor
_______________
which
transmit
electrical
signals,
and
____________ cells.
2. Each neurone consists of a cell __________ and associated nerve
fibres: one axon and several _______________.
3. An axon is surrounded by a __________________ sheath of
insulating material whose presence greatly increases the
_____________ at which nerve impulses can be transmitted through
the fibre.
4. Glial
cells
_____________
neurones,
maintain
a
stable
environment
around
neurones
and
produce
the
myelin
________________.
5. _______________________ continues until adolescence. The myelin
sheath is destroyed by certain _______________ causing loss of
coordination.
6. A synaptic __________ is a tiny space between two neurones.
Information is transmitted at a synapse by a chemical called a
_________________________ being released from vesicles in the
_____________________ neurone. The neurotransmitter combines
with ____________ sites on the postsynaptic membrane.
7. The receptor determines whether the signal generated is
___________ or inhibitory.
8. To
prevent
continuous
stimulation
of
__________________
neurones,
neurotransmitters
are
________________
from
the
synaptic cleft by ________ action or re-uptake.
9. The cumulative effect of a series of _____________ stimuli that
together bring about an impulse is called _____________________.
10. In a _________________ neural pathway, nerve impulses from
several sources meet at a common destination.
11. In a ________________ neural pathway, the route along which a
nerve impulse travels divides, allowing information to pass to
several destinations.
12. In a _______________ pathway, later neurones form synapses
with earlier ones, allowing the nerve impulse to be sent
_________ through the circuit.
13. The ability of brain cells to become ____________ as a result
of new environmental experiences is called __________ of
response.
14. ____________________
are
chemicals
that
function
like
neurotransmitters and act as natural _________________.
15. ____________________
is
a
neurotransmitter
secreted
by
neurones in the brain’s _________________ pathway which is
activated by certain types of beneficial behaviour.
16. Chemicals that act like neurotransmitters are used in the
treatment of some disorders. An _____________ is a chemical that
stimulates specific receptors in postsynaptic neurones and
___________
the
action
of
the
naturally
occurring
neurotransmitter. An ____________ blocks receptors and prevent
the neurotransmitter from acting on them.
17. Some drugs act by _________________ the enzyme that degrades
the
natural
neurotransmitter
or
by
inhibiting
its
_________________.
18. Many __________________ drugs bring about their effect by
affecting the brain’s reward circuit thereby altering the
person’s ___________, perception and _______________. The drugs
may act as agonists, antagonists or inhibitors.
19. An increase in the number and sensitivity of neurotransmitter
receptors following repeated exposure to a drug that is an
antagonist
is
called
___________________
and
leads
to
______________.
20. A decrease in the number and sensitivity of neurotransmitter
receptors following repeated exposure to a drug that is an
agonist is called ___________________ and leads to drug
_____________.
addiction
agonist
altered
antagonist
back
behaviour
body
cleft
converging
dendrites
desensitisation
diseases
diverging
dopamine
endorphins
enzyme
excitatory
glial
inhibiting
mimics
mood
myelin
myelination
neurones
neurotransmitter
painkillers
plasticity
postsynaptic
presynaptic
receptor
recreational
removed
re-uptake
reverberating
reward
sensitisation
sheath
speed
summation
support
tolerance
weak