Question

If a pre-synaptic neuron released a neurotransmitter onto a post-synaptic neuron and caused potassium (K⁺⁾ channels to open, what effect would this have on the post-synaptic neuron?

	A.	the post-synaptic neuron would likely generate an inhibitory post-synaptic potential (IPSP)
	B.	the post-synaptic neuron would likely generate an excitatory post-synaptic potential
	C.	the post-synaptic neuron would likely release a neurotransmitter
	D.	the post-synaptic neuron would likely produce an action potential

Answer 1

Correct answer is A.

There are inhibitory neurons also.​​ Most of them cause inhibitory effect by Hyperpolarizing the postsynaptic membrane. An inhibitory presynaptic neuron causes increase in polarity of postsynaptic membrane from -70mV to -75mV. This increase the gap between the polarity of the postsynaptic membrane and the threshold potential (-60mV) . This temporary local depolarization the postsynaptic neuron is called Inhibitory postsynaptic potential (IPSP) and a synapse having an inhibitory presynaptic neuron is called inhibitory synapse. At this synapse, the release of a neurotransmitter cause opening of specific ion channels i.e., potassium ion channel and chloride ion channels. Movement of these ions occurs down the concentration gradient causing hyperpolarisation of postsynaptic membrane.