Final answer:
The synaptic cleft is a small gap, approximately 20 nm wide, that separates the presynaptic and postsynaptic cells in a chemical synapse, allowing for the rapid diffusion and degradation of neurotransmitters.
Step-by-step explanation:
The narrow gap between the two cells in a chemical synapse is known as the synaptic cleft, which is approximately 20 nm (0.02 μm) wide. This small gap is essential for neurocommunication, as it allows the neurotransmitter to diffuse rapidly from the presynaptic element to the postsynaptic element.
The space between the presynaptic cell and the postsynaptic cell is vital for the fast diffusion of neurotransmitters. Moreover, enzymes located in the synaptic cleft degrade certain types of neurotransmitters to terminate the neuronal signal.