Which structure releases neurotransmitters into the synapse?

Which structure releases neurotransmitters into the synapse?

• A. Axon terminals
• B. Dendrites
• C. Soma
• D. Myelin sheath

Answer: (A)

The key idea is where chemical communication between neurons starts. Neurotransmitters are stored in vesicles at the end of the axon, in structures called axon terminals (presynaptic terminals). When an action potential arrives, calcium channels open, calcium enters, and these vesicles fuse with the presynaptic membrane to release neurotransmitters into the synaptic cleft. The neurotransmitters then bind to receptors on the postsynaptic membrane to continue signaling. Dendrites are mainly the receiving parts of a neuron; they hold receptors to detect neurotransmitters but do not release them into the synapse under normal conditions. The soma processes and integrates signals from many inputs but isn’t the site where neurotransmitter release into the synapse occurs. The myelin sheath insulates the axon to speed electrical transmission, not to release neurotransmitters.

The key idea is where chemical communication between neurons starts. Neurotransmitters are stored in vesicles at the end of the axon, in structures called axon terminals (presynaptic terminals). When an action potential arrives, calcium channels open, calcium enters, and these vesicles fuse with the presynaptic membrane to release neurotransmitters into the synaptic cleft. The neurotransmitters then bind to receptors on the postsynaptic membrane to continue signaling.

Dendrites are mainly the receiving parts of a neuron; they hold receptors to detect neurotransmitters but do not release them into the synapse under normal conditions. The soma processes and integrates signals from many inputs but isn’t the site where neurotransmitter release into the synapse occurs. The myelin sheath insulates the axon to speed electrical transmission, not to release neurotransmitters.