Final answer:
An electrical synapse includes gap junctions that allow for the direct passage of ions between electrically active cells, enabling rapid signal transmission important for reflexes and neuronal synchronization.
Step-by-step explanation:
An electrical synapse includes specialized junctions known as gap junctions which allow ions to pass directly from one cell to another. These junctions consist of channel proteins that connect the presynaptic and postsynaptic membranes, ensuring a virtually instantaneous transmission of electrical signals between cells. This characteristic is crucial for reflexes and the synchronization of electrical activity in groups of neurons, such as those regulating slow-wave sleep in the thalamus.