What happens to vesicles when calcium ions flood the terminal button?

• A. They absorb neurotransmitters
• B. They fuse with the membrane to release neurotransmitters
• C. They generate action potentials
• D. They separate from the neuron

Answer: (B)

When calcium ions flood the terminal button, they trigger a series of biochemical events that lead to the fusion of synaptic vesicles with the presynaptic membrane. This fusion is essential for the release of neurotransmitters into the synaptic cleft, where they can then bind to receptors on the postsynaptic neuron and propagate the signal. The influx of calcium ions is a critical signal that initiates this process; it facilitates the interaction between the vesicles and the membrane, allowing for the contents of the vesicles—neurotransmitters—to be released into the synaptic space. This mechanism is fundamental to synaptic transmission and communication between neurons.