Resting Potential

Definition

Resting potential is the electrical charge difference across a neuron's membrane when the neuron is not actively sending a signal. It typically ranges from -60 to -70 millivolts, and is essential for maintaining the readiness of a neuron to fire action potentials. This stable state results from the distribution of ions, primarily sodium (Na+) and potassium (K+), across the membrane and the selective permeability of the neuronal membrane.

5 Must Know Facts For Your Next Test

1. Resting potential is maintained by the unequal distribution of sodium and potassium ions across the neuron's membrane, with more Na+ outside and more K+ inside.
2. The permeability of the neuronal membrane to K+ is higher at rest, allowing more K+ ions to flow out of the neuron than Na+ flowing in, contributing to the negative charge.
3. The sodium-potassium pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell for every ATP molecule used, further establishing resting potential.
4. Resting potential is crucial because it sets the stage for action potentials; a significant change in resting potential can trigger these rapid signals.
5. The value of resting potential can vary slightly among different types of neurons but generally remains around -70 mV, depending on cellular conditions.

Review Questions

• How does resting potential prepare a neuron for firing an action potential?
  • Resting potential establishes a baseline electrical charge across the neuron's membrane, typically around -70 mV. This negative charge creates an electrochemical gradient that is essential for rapid depolarization when an action potential occurs. When a stimulus is strong enough to depolarize the membrane past a certain threshold, voltage-gated ion channels open, leading to an influx of sodium ions that generates the action potential. Without resting potential, this preparatory state wouldn't exist, making it impossible for neurons to effectively transmit signals.
• Discuss how ion channels contribute to maintaining resting potential in neurons.
  • Ion channels play a pivotal role in establishing and maintaining resting potential by controlling the movement of specific ions across the neuronal membrane. Potassium channels allow K+ ions to flow out of the neuron more readily than sodium channels permit Na+ ions to enter. This selective permeability helps create a negative internal environment relative to the outside. Additionally, during changes in activity, these channels can open or close to help regulate the electrical state of the neuron, highlighting their importance in both resting potential and action potentials.
• Evaluate how disturbances in resting potential can affect neuronal signaling and overall brain function.
  • Disturbances in resting potential can significantly impair neuronal signaling by altering the ability of neurons to fire action potentials. For instance, if resting potential becomes less negative (depolarized), it may lead to increased excitability, causing neurons to fire too easily or too frequently. Conversely, if it becomes more negative (hyperpolarized), neurons may become less responsive, hindering signal transmission. Such imbalances can have serious implications for overall brain function, potentially contributing to conditions like epilepsy or other neurological disorders where signaling is disrupted.

Related terms

Action Potential: A rapid rise and fall in voltage or membrane potential across a cellular membrane, which occurs when a neuron sends signals along its axon.

Ion Channels: Protein structures that allow specific ions to move across the cell membrane, playing a crucial role in establishing and maintaining resting potential.

Sodium-Potassium Pump: A membrane protein that transports sodium ions out of the cell and potassium ions into the cell, crucial for maintaining resting potential and returning the neuron to its resting state after an action potential.