A synapse is a junction between two neurons in the nervous system. The actual distance between the ends of the two cells is called the synaptic cleft. The distance of this cleft is tiny in order to allow electrical or chemical signals to be effectively transmitted between the two cells. This is how the nervous system is able to send signals so rapidly across the body. If the synaptic cleft were to be increased so that the distance between the two cells were larger, then the signal would not be able to travel as effectively between the neurons. This would slow down and degrade the neural signal and lead to a less effective nervous system.