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Objective 5:
How are resting potentials restored? (5d)
Links under Objective 6 (below) may be helpful for 5f.
How much Na+/K+ exchanged in
a single action potential? (5g)
Neuroscience: A Journey Through the Brain - The
Action Potential
Objective 6:
Schwann cells
Myelin sheath
What is a secondary function of Schwann cells? See the caption to
the image at top left for an answer.
Objective 8:
What change must be induced in the membrane
potential of a post-synaptic neuron for an action potential to be
induced? (8d)
How are neurotransmitters removed
from the synapse? (8f)
Objective 9:
Where are neurotransmitters
synthesized, packaged, and transported? (9b)
Objective 11:
Comparative nervous systems
Objective 12:
Reflex arcs
Objective 13:
The
autonomic nervous system (13b)
Control
of heartbeat - an example of autonomic control (13e)
What type of cells are neurosecretory cells of the adrenal medulla modified from? (13f)
Objective 14:
Trends in vertebrate brain evolution
The neocortex
Optional Supplementary Material:
You need your sleep!
Brain size
matters for sex - The fear centre finds a role in arousal
Sleep
boosts lateral thinking - Study shows the value of sleeping
on a problem.
Neurologic drugs
One
of the World's Most Powerful Neurotoxins from a Snail?
Chips
Coming to a Brain Near You - next in line to get that memory
upgrade isn't your computer, it's you. |
MANY NEUROLOGICAL DRUGS EXERT THEIR EFFECTS AT SYNAPSES
Because synapses act as control valves in the nervous system, and
because their proper function depends on a very delicate balance between transmitter
substance, deactivating enzyme, and membrane sensitivity, it is not surprising
that synaptic malfunctions have been implicated in several mental disorders – among
them schizophrenia – or that many neurological drugs exert their effects
directly or indirectly at synapses.
Neurological drugs can alter synaptic function in a variety of
ways. They may turn off certain synapses by:
- interfering with synthesis of the appropriate transmitter substance
in the cell body of the neuron.
- interfering with the transport of the transmitter
down the axon, from the cell body where it is synthesized to the synaptic
terminal where it is packaged
into synaptic vesicles.
- preventing release of the transmitter from the
vesicles.
- blocking the receptor sites on the postsynaptic membranes, so
that the transmitter has no effect even if released.
Other drugs can induce excessive and uncontrolled firing of postsynaptic
cells by:
- stimulating massive release of transmitter substance from the vesicles.
- mimicking
the effect of the transmitter.
- Inhibiting destruction of the transmitter
once it has done its job. Cocaine, for instance, binds to and inhibits
the protein responsible for removing
the transmitter dopamine from dopamine synapses. Dopamine therefore
remains active,
producing overstimulation of postsynaptic neurons.
OPTIONAL: Forbes.com - New
Neurological Drugs to Watch.
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