What is a synapse?

A synapse is best defined as a junction between two neurons. It is the critical site where communication occurs, allowing one neuron to transmit signals to another. The synapse consists of a pre-synaptic terminal, which contains neurotransmitters that are released into the synaptic cleft, and a post-synaptic membrane, where receptors are located to receive these neurotransmitters. This process is fundamental for neural communication, influencing everything from muscle movement to complex cognitive functions.

The other provided options do not accurately capture the definition of a synapse. While muscle cells and glands play vital roles in the body, they are not involved in the transmission of nerve impulses in the way synapses are. Similarly, while the brain includes many crucial structures that facilitate neuronal communication, it is not itself a synapse. Therefore, understanding that a synapse is a specialized connection between neurons is essential for grasping how signals are conveyed throughout the nervous system.