What is the presynaptic terminal?

What is the presynaptic terminal?

• A. The region of the dendrite that receives input.
• B. The cell body that integrates signals.
• C. The gap between neurons.
• D. The part of the neuron that contains synaptic vesicles and releases neurotransmitters.

Answer: (D)

The presynaptic terminal is the end of the axon where communication with the next cell begins. It contains synaptic vesicles filled with neurotransmitters and the machinery needed to release them. When an action potential reaches this terminal, voltage-gated calcium channels open, allowing calcium to enter. The rise in calcium triggers vesicles to fuse with the presynaptic membrane and release their neurotransmitter contents into the synaptic cleft. Those neurotransmitters then bind to receptors on the postsynaptic cell to propagate the signal. This region is distinct from dendrites, which receive input, and from the cell body, which integrates signals; the gap between neurons is the synaptic cleft, which is bridged by the released neurotransmitters from the presynaptic terminal.

The presynaptic terminal is the end of the axon where communication with the next cell begins. It contains synaptic vesicles filled with neurotransmitters and the machinery needed to release them. When an action potential reaches this terminal, voltage-gated calcium channels open, allowing calcium to enter. The rise in calcium triggers vesicles to fuse with the presynaptic membrane and release their neurotransmitter contents into the synaptic cleft. Those neurotransmitters then bind to receptors on the postsynaptic cell to propagate the signal. This region is distinct from dendrites, which receive input, and from the cell body, which integrates signals; the gap between neurons is the synaptic cleft, which is bridged by the released neurotransmitters from the presynaptic terminal.