Indicate whetherthe statements below are true or false. If a statement is false, explain why it is false
A. Neurotransmitters are small molecules released into the synaptic cleft after the fusion of synaptic vesicles with the presynaptic membrane.
B. Action potentials are usually mediated by voltage-gated Ca2+ channels.
C. Voltage-gated Na+ channels become automatically inactivated shortly after opening, which ensures that the action potential cannot move backward along the axon.
D. Voltage-gated K+ channels also open immediately in response to local depolarization, reducing the magnitude of the action potential.
A. True.
B. False. Action potentials are usually mediated by voltage-gated Na+ channels.
C. True.
D. False. Voltage-gated K+ channels respond more slowly than the voltage-gated Na+ channels. Because voltage-gated K+ channels do not open until the action potential reaches its peak, they do not affect its magnitude. Instead, they help to restore the local membrane potential quickly while the voltage-gated Na+ channels are in the inactivated conformation.
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