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Postsynaptic Potentials

What is the difference between inhibitory and excitatory postsynaptic potentials? An action potential traveling through a neuron transmits a signal to an adjacent neuron across a synapse. The signal can result in an excitatory postsynaptic potential that increases the probability of an action potential in the postsynaptic neuron. Alternatively the signal can result in an inhibitory postsynaptic potential that decreases the probability of an action potential in the postsynaptic neuron. But systems work on the same basic principle – the action potential in the presynaptic neuron triggers the release of neurotransmitters that cross the synapse and bind to receptors on the postsynaptic neuron. Binding to the receptor causes the opening and/or closing of ion channels. The major difference between the two systems is the types of ion channels affected and if they are opened or closed.

View the animation below, then complete the quiz to test your knowledge of the concept.






1An inhibitory post synaptic potential (IPSP)...
A)will make the membrane potential of a neuron’s inner cell membrane more positive.
B)will make the membrane potential of a neuron’s outer cell membrane more positive.
C)will make the membrane potential of a neuron’s inner cell membrane more negative.
D)will make the membrane potential of a neuron’s outer cell membrane more negative.
E)will lower the membrane threshold potential of a neuron.



2An excitatory post synaptic potential (EPSP)...
A)will make the membrane potential of a neuron’s inner cell membrane more positive.
B)will make the membrane potential of a neuron’s outer cell membrane more positive.
C)will make the membrane potential of a neuron’s inner cell membrane more negative.
D)will make the membrane potential of a neuron’s outer cell membrane more negative.
E)will lower the membrane threshold potential of a neuron.



3An EPSP will cause...
A)chloride gates to open and allow chloride ions to diffuse into the cytosol.
B)potassium gates to open and allow potassium to diffuse out of the cytosol.
C)sodium gates to open, allowing sodium to diffuse out of the cell.
D)potassium gates to open, allowing potassium to diffuse into the cell.
E)both sodium and potassium gates to open, allowing sodium to diffuse into the cell and potassium to diffuse out of the cell.



4EPSPs and IPSPs have a long term effect on a neuron.
A)True
B)False



5IPSPs can use different methods to obtain the same results.
A)True
B)False







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