Which term refers to an event that activates a neuron and begins an action potential?

• A. Resting potential
• B. Synaptic cleft
• C. Refractory period
• D. Threshold stimulus

Answer: (D)

Verified step by step guidance

1. Understand the concept of a neuron: Neurons are specialized cells in the nervous system that transmit electrical signals. These signals are initiated by specific events that change the electrical state of the neuron.
2. Learn about the resting potential: The resting potential is the baseline electrical charge of a neuron when it is not actively transmitting signals. It is maintained by ion gradients across the cell membrane.
3. Explore the threshold stimulus: A threshold stimulus is the minimum level of stimulation required to depolarize the neuron and initiate an action potential. This is the event that activates the neuron.
4. Understand the action potential: Once the threshold stimulus is reached, voltage-gated ion channels open, allowing ions to flow across the membrane. This creates a rapid change in electrical charge, known as the action potential, which propagates along the neuron.
5. Clarify related terms: The synaptic cleft is the gap between neurons where neurotransmitters are released, and the refractory period is the time after an action potential during which the neuron cannot fire again. These terms are not directly related to the activation of a neuron by a threshold stimulus.