What occurs at a synapse?

At a synapse, a nerve impulse passes from one neuron to another, which is a critical process in the functioning of the nervous system. The synapse is the junction between two neurons, where the transmission of signals occurs. When an electrical impulse, or action potential, reaches the end of one neuron (presynaptic neuron), it triggers the release of neurotransmitters. These chemicals cross the synaptic cleft and bind to receptors on the surface of the next neuron (postsynaptic neuron), facilitating the continuation of the nerve impulse. This process is essential for communication within the nervous system, enabling signals to be transmitted rapidly and efficiently across networks of neurons.

The other choices describe different physiological processes. Hormone secretion by glands refers to endocrine signaling, which does not occur at synapses. Measuring reaction time is related to how quickly an organism can respond to stimuli but does not directly describe the action that takes place at a synapse. Initiating a reflex involves a more complex neural pathway, often involving multiple synapses, but it does not define the fundamental function of a synapse itself.