Resting Membrane Potential

Definition

Resting membrane potential refers to the electrical charge difference across the neuronal membrane when a neuron is not actively transmitting signals. This potential is crucial for maintaining the overall excitability of neurons and plays a key role in the generation of action potentials and the transmission of signals through chemical and electrical synapses.

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 neuron is negatively charged compared to the outside.
2. This potential is primarily determined by the distribution of potassium (K+) and sodium (Na+) ions across the neuronal membrane and the selective permeability of the membrane to these ions.
3. Resting membrane potential is essential for the neuron's ability to respond to stimuli, as any changes in this potential can lead to action potentials if certain thresholds are reached.
4. The sodium-potassium pump actively maintains resting membrane potential by pumping 3 Na+ ions out of the cell and 2 K+ ions into the cell, consuming ATP in the process.
5. Resting membrane potential can be influenced by external factors such as changes in ion concentrations in the extracellular environment or drugs that affect ion channel activity.

Review Questions

• How does resting membrane potential contribute to neuronal excitability?
  • Resting membrane potential sets the stage for neuronal excitability by creating an electrochemical gradient across the neuronal membrane. This gradient means that when a stimulus occurs, there can be a rapid influx of sodium ions (Na+) when channels open, leading to depolarization. If this depolarization reaches a certain threshold, it triggers an action potential, allowing for signal transmission.
• Discuss the role of ion channels in establishing and maintaining resting membrane potential.
  • Ion channels play a vital role in establishing and maintaining resting membrane potential by selectively allowing certain ions to pass through the neuronal membrane. Potassium (K+) channels, which are more numerous than sodium (Na+) channels at rest, enable K+ ions to flow out of the cell, contributing to the negative charge inside. Conversely, Na+ channels are less active at rest, keeping sodium concentrations low inside. The balance created by these channels helps stabilize resting membrane potential.
• Evaluate how changes in extracellular ion concentrations could affect resting membrane potential and subsequent neuronal signaling.
  • Changes in extracellular ion concentrations can significantly impact resting membrane potential and neuronal signaling. For instance, an increase in extracellular potassium (K+) concentration can reduce the gradient driving K+ out of the cell, leading to a less negative resting potential, which may cause neurons to become more excitable or even depolarized continuously. Conversely, a decrease in extracellular sodium (Na+) can hinder action potentials from occurring, as there wouldn't be enough influx of Na+ when channels open. This illustrates how fluctuations in ion levels can disrupt normal neural communication.

Related terms

Action Potential: A rapid change in membrane potential that occurs when a neuron sends information down its axon, characterized by depolarization followed by repolarization.

Ion Channels: Proteins embedded in the cell membrane that allow specific ions to enter or exit the neuron, contributing to the establishment and maintenance of resting membrane potential.

Equilibrium Potential: The electrical potential difference across a membrane that exactly balances the concentration gradient for a specific ion, leading to no net movement of that ion across the membrane.