Unformatted text preview: y on the
membrane of the receiving neuron (in this case,
acetylcholinesterase acts on Ach to produce
acetyl and choline). This reference is to the
cholinergic synapse pictured. Continued action
of the NT at adrenergic synapses is prevented
by reuptake of the NT (norepinephrine) by the
(b) The neurotransmitter must be deactivated so that
it does not continue to stimulate the receiving
neuron (continued stimulation would lead to
depletion of neurotransmitter and fatigue of the
nerve). Deactivation allows recovery of the neuron
so that it can respond to further impulses.
(c) Transmission is unidirectional because the
synapses is asymmetric in structure and function.
The presynaptic membrane does not possess the
receptors for the NT and the postsynaptic neuron
does not have the stores of NT within vesicles. 5. Note numbering error
The amount of neurotransmitter released influences
the response of the receiving cell (response strength
is proportional to amount of neurotransmitter
released). Integration at Synapses (page 80)
1. Integration refers to the interpretation and
coordination (by the central nervous system) of inputs
from many sources (inputs may be inhibitory or
excitatory). 2. (a) Summation: The additive effect of presynaptic
inputs (impulses) in the postsynaptic cell (neuron
or muscle fiber).
(b) Spatial summation refers to the summation
of impulses from separate axon terminals
arriving simultaneously at the postsynaptic cell.
Temporal summation refers to the arrival of
several impulses from a single axon terminal in
rapid succession (the postsynaptic potentials are
so close together in time that they can sum to
generate an action potential). 3. (a) Acetylcholine is the NT involved; arrival of an
action potential at the neuromuscular junction
causes the release of Ach from the synaptic
(b) Ach causes depolarization of the postsynaptic
membrane (in this case,the sarcolemma). Note:
The depolarization in response to the arrival of
an action potential at the postsynaptic cell is
essentially the same as that occurring at any
excitatory synapse involving Ach...
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This document was uploaded on 01/28/2014.
- Winter '13