Chapter 12, Problem 19CP

Summary Introduction

To review:

The similarities and differences between inhibitory and excitatory postsynaptic potentials.

Introduction:

When the nerve impulse reaches the synaptic bulb of a neuron, the voltage-gated calcium channels open. It forces the exocytosis of synaptic vesicles that contain the neuron from the pre-synaptic end of an axon. When a neurotransmitter is released from the vesicle, it binds to its specific receptors present on the postsynaptic membrane of another neuron. This binding opens the ligand-gated channels, through which the ions flow.

The flow of ions changes the voltage across the cell membrane and this alteration is known as postsynaptic potential. On the basis of the ions involved, the depolarization and hyperpolarization occur, that is, the sodium ions cause depolarization, whereas potassium ions, as well as chloride ions, cause hyperpolarization.