Resting membrane potential

Definition

Resting membrane potential is the electrical charge difference across the plasma membrane of a neuron or other excitable cell when it is not actively transmitting signals. This potential is primarily determined by the distribution of ions, particularly sodium (Na+) and potassium (K+), across the membrane, which establishes a stable environment necessary for cellular functions like communication.

5 Must Know Facts For Your Next Test

1. The typical resting membrane potential of a neuron is around -70 mV, indicating that the inside of the cell is negatively charged compared to the outside.
2. Potassium ions (K+) have a higher concentration inside the cell, while sodium ions (Na+) are more concentrated outside, leading to the negative charge when at rest.
3. The resting membrane potential is crucial for the excitability of neurons, allowing them to respond quickly to stimuli.
4. Resting membrane potential is established by both passive ion diffusion and active transport mechanisms like the sodium-potassium pump.
5. Any change in the resting membrane potential can affect how easily a neuron can generate an action potential, impacting nerve signaling.

Review Questions

• How does the distribution of ions contribute to the establishment of resting membrane potential?
  • The distribution of ions, particularly potassium (K+) and sodium (Na+), plays a crucial role in establishing resting membrane potential. Potassium ions are more concentrated inside the neuron, while sodium ions are more concentrated outside. This unequal distribution creates an electrical gradient where K+ tends to flow out of the cell while Na+ flows in, contributing to a negative charge inside relative to the outside, thus establishing the resting membrane potential.
• Discuss the role of the sodium-potassium pump in maintaining resting membrane potential and how it relates to cellular energy use.
  • The sodium-potassium pump is essential for maintaining resting membrane potential by actively transporting sodium ions out of the cell and potassium ions into the cell against their concentration gradients. For every three Na+ ions pumped out, two K+ ions are brought in. This process requires energy in the form of ATP because it is an active transport mechanism. Without this pump functioning properly, resting membrane potential could not be maintained, leading to issues with cellular excitability and signaling.
• Evaluate how alterations in resting membrane potential can impact neuronal communication and overall nervous system function.
  • Alterations in resting membrane potential can significantly impact neuronal communication by affecting a neuron's ability to generate action potentials. If the resting membrane potential becomes less negative (depolarization), a neuron may become more excitable and more likely to fire an action potential. Conversely, hyperpolarization, where the resting potential becomes more negative, can make it harder for a neuron to fire. These changes can disrupt normal communication within the nervous system, potentially leading to conditions like seizures or paralysis if not properly regulated.

Related terms

Ion Channels: Proteins embedded in the cell membrane that allow specific ions to pass in and out of the cell, playing a critical role in establishing and maintaining resting membrane potential.

Sodium-Potassium Pump: A type of active transport mechanism that uses ATP to move sodium ions out of the cell and potassium ions into the cell, crucial for maintaining the resting membrane potential.

Action Potential: A rapid, temporary change in membrane potential that occurs when a neuron is activated, allowing for signal transmission; it follows the resting membrane potential.