Resting membrane potential

Definition

Resting membrane potential is the electrical potential difference across the plasma membrane of a cell when it is not actively signaling, typically around -70 mV in neurons. This potential is primarily determined by the distribution of ions, especially sodium (Na+), potassium (K+), chloride (Cl-), and the permeability of the membrane to these ions. It plays a crucial role in maintaining the excitability of cells, particularly neurons and muscle cells, and sets the stage for action potentials and other signaling mechanisms.

5 Must Know Facts For Your Next Test

1. The resting membrane potential is largely influenced by the permeability of the membrane to K+, which tends to leak out of the cell, making the inside more negative.
2. The sodium-potassium pump actively transports 3 Na+ ions out and 2 K+ ions into the cell, helping maintain the resting membrane potential.
3. Resting membrane potential is essential for proper neuronal signaling; deviations from this potential can lead to hyperpolarization or depolarization.
4. Changes in ion concentration outside the cell can significantly affect resting membrane potential, impacting cellular excitability.
5. Resting membrane potential provides a baseline state that is necessary for neurons to respond effectively to stimuli and generate action potentials.

Review Questions

• How does the distribution of ions contribute to the establishment of resting membrane potential?
  • The distribution of ions across the cell membrane is critical for establishing resting membrane potential. The membrane is more permeable to potassium (K+) than sodium (Na+), leading to K+ leaking out of the cell, which makes the inside of the cell more negative. The sodium-potassium pump further maintains this balance by actively transporting Na+ out of the cell and K+ into it, contributing to a typical resting potential of around -70 mV.
• Discuss the role of ion channels in maintaining resting membrane potential and how changes in their function can affect cellular excitability.
  • Ion channels play a vital role in maintaining resting membrane potential by allowing specific ions to move across the membrane. For instance, potassium channels allow K+ ions to flow out of the cell, which is essential for keeping the inside negative. If these channels malfunction or if there are changes in their activity, it can lead to altered resting potentials, which may cause increased excitability or decreased responsiveness in neurons, impacting overall cellular function.
• Evaluate how resting membrane potential is critical for action potential generation in neurons and its implications for neuronal signaling.
  • Resting membrane potential is crucial for action potential generation because it provides a baseline state that neurons can rapidly change from during signaling. When a stimulus depolarizes the neuron beyond a certain threshold, voltage-gated sodium channels open, allowing Na+ influx and leading to an action potential. If resting membrane potential were altered significantly, it would disrupt this process, affecting the ability of neurons to communicate effectively and potentially impairing complex functions such as reflexes and voluntary movements.

Related terms

Ion channels: Protein structures that allow ions to pass through the cell membrane, playing a key role in generating and maintaining resting membrane potential.

Nernst equation: A mathematical equation used to calculate the equilibrium potential for a specific ion based on its concentration gradient across the membrane.

Action potential: A rapid change in membrane potential that occurs when a neuron or muscle cell is stimulated, leading to depolarization followed by repolarization.