Which part of a sensory neuron is considered the 'gatekeeper' of the signals?

Which part of a sensory neuron is considered the 'gatekeeper' of the signals?

• A. Dendritic zone
• B. Soma
• C. Axon hillock
• D. Synaptic knobs

Answer: (C)

Signals from other neurons are received mainly by the dendrites and soma, where many inputs are integrated. The axon hillock acts as the gatekeeper because it concentrates the voltage-gated Na+ channels and is the region where the summed membrane potential must reach a threshold to trigger an action potential. When the combined depolarization at the axon hillock crosses this threshold, an action potential is initiated and then propagates along the axon. So, it’s the axon hillock’s role in threshold detection and initiation of the spike that makes it the decisive control point for whether the neuron fires. Dendritic zones mainly gather input, the soma integrates cellular signals, and synaptic knobs release neurotransmitters at the synapse rather than deciding whether to fire.

Signals from other neurons are received mainly by the dendrites and soma, where many inputs are integrated. The axon hillock acts as the gatekeeper because it concentrates the voltage-gated Na+ channels and is the region where the summed membrane potential must reach a threshold to trigger an action potential. When the combined depolarization at the axon hillock crosses this threshold, an action potential is initiated and then propagates along the axon. So, it’s the axon hillock’s role in threshold detection and initiation of the spike that makes it the decisive control point for whether the neuron fires. Dendritic zones mainly gather input, the soma integrates cellular signals, and synaptic knobs release neurotransmitters at the synapse rather than deciding whether to fire.