How do neurotransmitters function at synapses?

Neurotransmitters play a crucial role in the communication between neurons at synapses. When an electrical impulse, known as an action potential, travels down a neuron and reaches the end of the axon, neurotransmitters are released into the synaptic cleft—the small gap between neurons. These chemicals then bind to specific receptors on the surface of the neighboring neuron, leading to the transmission of a signal.

This process allows for the rapid communication necessary for various functions within the nervous system, including reflexes, coordination, and higher cognitive processes. Each neurotransmitter has unique functions and effects, influencing whether the next neuron will propagate the signal or inhibit it. This intricate signaling is fundamental to the overall function of the nervous system and underpins everything from muscle movement to emotional responses.

While muscle contraction is indeed related to neurotransmitter action, it is not the primary function of neurotransmitters at synapses. Similarly, neurotransmitters do not release hormones; that function is carried out by different glands in the endocrine system. Providing oxygen to neurons is also not a role of neurotransmitters; oxygen delivery is primarily managed through blood circulation. Thus, the correct answer highlights the primary function of neurotransmitters in signal transmission between neurons.