Summation of postsynaptic potentials determines whether or not an action potential will be generated at the axon hillock. The final amplitude of the summed potentials is dependent upon
A) distance the post-synaptic potential has traveled
B) the polarity of the potential (epsp or ipsp)
C) the timing of the potential (did they arrive close enough together to be summed)
D) All of the choices will affect the final amplitude.

Question

Quizplus · Accepted Answer

All of the choices can affect the final amplitude of the summed potentials. The distance the post-synaptic potential has traveled affects its strength due to attenuation and divergence. The polarity of the potential (EPSP or IPSP) determines whether it depolarizes or hyperpolarizes the membrane potential, respectively. The timing of the potential is important because only potentials that arrive close enough together (temporal summation) or from different presynaptic inputs (spatial summation) will be added together. Therefore, all of these factors play a role in determining whether or not an action potential will be generated at the axon hillock.

Summation of Postsynaptic Potentials Determines Whether or Not an Action