By which process do neurotransmitters travel across a synapse?

Neurotransmitters travel across a synapse through a process called synaptic transmission. Here are the steps:

1. An electrical signal, or action potential, travels down a neuron's axon.

2. When this signal reaches the end of the neuron (the axon terminal), it triggers the release of neurotransmitter molecules stored in small sacs called vesicles.

3. These neurotransmitters are released into the synaptic cleft, the small space between the neurons.

4. The neurotransmitters then bind to specific receptors on the receiving neuron's dendrites. This binding can either stimulate or inhibit a new action potential in the receiving neuron.

5. After the neurotransmitters have done their job, they are either broken down by enzymes, taken back up into the sending neuron for reuse (a process called reuptake), or simply diffuse away.

This process allows neurons to pass signals on to other neurons, muscles, or glands, and is fundamental to all of the brain's activities.