Question

Neurotransmitters (or any stimulus) produce one of two types of effects on the target cell: an EPSP or an IPSP. Explain what both EPSPs and IPSPs are, whether each is a depolarization or repolarization, what ranges of MP voltages each would have, and which ion(s) each would involve. What is the function of an EPSP? Of an IPSP?

Answer 1

What is EPSP and IPSP:

EPSP-stands for excitatory postsynaptic potential.It is an action potential fired by presynaptic neuron which generates an action potential in the post synaptic neuron.

IPSP​​​- stands for inhibitory postsynaptic potential.It occurs when an action potential fired from presynaptic neuron inhibits the generation of action potential in the post synaptic neuron.

Whether it is depolarization or repolarization?

EPSP- since an action potential is generated in the post synaptic neuron, positive ions starts entering.This causes Depolarization.

IPSP-​​ in this there is entry of negatively charged ions into postsynaptic cell,which causes temporary Hyperpolarization.

Ranges of membrane potential:

EPSP: a single EPSP causes membrane potential to rise from resting potential -60 to -35.Bt this is not enough to generate action potential.Therefore EPSPs get summed up to produce an action potential in post synaptic cell.

IPSP: an IPSP causes hyperpolarization and decreases the membrane potential from -60 (resting potential) to -70.

Ions involved:

Epsp- there influx of Na+ ions from ligand gated channels.

IPSP- there is influx of negatively charged ions like Cl- or efflux of K+

Functions:

EPSP increases membrane potential in the post synaptic cells.Thus it helps in generation of an action potential and propagation of that to further cells.

IPSP inhibits the action potential by decreasing membrane potential,making it less than resting potential and thus is used to stop the spreading of action potential.