Resting potential

Definition

Resting potential is the electrical charge difference across a neuron's membrane when it is not actively transmitting signals, typically around -70 mV. This state is essential for neurons to be ready to fire an action potential, highlighting the importance of membrane structure and ion gradients maintained by various transport mechanisms.

5 Must Know Facts For Your Next Test

1. Resting potential is maintained primarily by the sodium-potassium pump, which moves 3 sodium ions out and 2 potassium ions into the neuron, creating a net negative charge inside.
2. Ion channels play a key role in establishing resting potential by allowing potassium ions to flow out of the cell while limiting sodium entry, helping to keep the inside negative.
3. The typical resting potential of a neuron ranges from -60 mV to -70 mV, which is crucial for generating action potentials when stimulated.
4. Changes in resting potential can influence neuronal excitability; if the potential becomes less negative (depolarization), it may lead to an action potential.
5. Resting potential is essential not just for neurons, but also for muscle cells and other excitable tissues that rely on changes in membrane potential for function.

Review Questions

• How does the structure of neuronal membranes contribute to the maintenance of resting potential?
  • The structure of neuronal membranes, particularly their lipid bilayer composition and embedded proteins, is crucial for maintaining resting potential. The selective permeability of the membrane allows potassium ions to move more freely than sodium ions, which helps create a negative charge inside. Additionally, proteins such as ion channels and the sodium-potassium pump are vital as they regulate ion flow, ensuring that there is a higher concentration of sodium outside the cell and potassium inside, thus maintaining the resting state.
• Discuss the role of the sodium-potassium pump in establishing and maintaining resting potential within neurons.
  • The sodium-potassium pump actively transports 3 sodium ions out of the neuron and 2 potassium ions into it. This process creates an electrochemical gradient that contributes significantly to the resting potential. By moving more positive charges out than in, it maintains a net negative charge inside the neuron. The continuous activity of this pump is crucial because it prevents gradual depolarization and ensures that the neuron remains ready to fire an action potential when needed.
• Evaluate how disruptions in resting potential could impact neuronal signaling and overall nervous system function.
  • Disruptions in resting potential can lead to significant issues in neuronal signaling. For example, if a neuron's resting potential becomes less negative due to increased sodium influx or impaired function of ion channels or pumps, it may become more excitable and prone to spontaneous firing. This can lead to conditions such as epilepsy or other neurological disorders where normal communication between neurons is disrupted. Additionally, altered resting potentials can affect muscle contraction and other critical physiological processes, demonstrating its central role in nervous system function.

Related terms

action potential: A rapid change in membrane potential that occurs when a neuron fires, moving from resting potential to a positive value before returning to its resting state.

sodium-potassium pump: A membrane protein that actively transports sodium ions out of the cell and potassium ions into the cell, crucial for maintaining resting potential.

ion channels: Proteins embedded in the cell membrane that allow specific ions to pass in and out of the cell, influencing the membrane potential.