# A&P 1 Ch 11 & 12

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Temporal summation of graded potentials occurs when several postsynaptic potentials arrive close to the same time from several different presynaptic neurons.
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Terms in this set (32)
All of the following are TRUE regarding neurotransmitters except

b. Removal of neurotransmitters from the synaptic cleft is not essential
a. Neurotransmitters can be degraded by enzymes

d. Neurotransmitters can diffuse away from the synaptic cleft

c. Neurotransmitters can be taken up by other cells in the vicinity of the synapse
Which of the following is FALSE?
Different voltages across the cell membrane are responsible for opening or closing various ion channels, allowing their ions to cross into the ECF or cytosol.
Threshold potential (-55mV) represents the level of membrane graded/local depolarization that would be sufficient to trigger the opening of voltage regulated sodium channels.
No matter how strong or weak the initial stimulus, once threshold is reached, an action potential will occur- and all action potentials have the same magnitude.
Graded potentials cannot increase the polarity of a cell membrane. They're only able to depolarize the membrane in order to attempt to reach threshold.