What are small knobs at the end of axons called that secrete neurotransmitters?

The small knobs at the end of axons that secrete neurotransmitters are known as terminal buttons. These structures play a crucial role in the communication between neurons. When an electrical signal, or action potential, travels down the axon and reaches the terminal buttons, it triggers the release of neurotransmitters into the synaptic cleft, allowing signals to be transmitted to the next neuron or target cell. This process is essential for the functioning of the nervous system and underlies many aspects of behavior, thought, and emotion.

In contrast to terminal buttons, synapses refer to the junctions where communication occurs between neurons, but they are not the structures that secrete neurotransmitters themselves. Dendrites are the branching projections of neurons that receive signals from other neurons. The soma, or cell body, contains the nucleus and other organelles vital for the neuron's maintenance and function. Each of these components plays a different role in neuronal communication, but terminal buttons are specifically responsible for the secretion of neurotransmitters.