What is a synapse?

A synapse is indeed defined as the point where one neuron sends a chemical signal to another. This is crucial in the communication between neurons in the nervous system. When a neuron is activated, it releases neurotransmitters into the synaptic cleft, which is the small gap between the presynaptic neuron (the sending neuron) and the postsynaptic neuron (the receiving neuron). The neurotransmitters then bind to receptors on the surface of the postsynaptic neuron, allowing the signal to continue its journey.

Understanding the synapse is fundamental to grasp how neurons communicate and how information is processed in the brain. This process is involved not only in simple reflexes but also in complex cognitive functions and emotional regulation. The other choices, such as the structure containing neurotransmitters or the electrical charge traveling down an axon, describe different components of the neuronal structure or function, but they do not encompass the specific role and definition of a synapse itself.