Resting Potential

Definition

Resting potential is the electrical charge difference across a neuron's membrane when it is not actively transmitting a signal, typically around -70 mV. This state is crucial for maintaining the neuron's ability to respond to stimuli and generate action potentials. The resting potential arises from the distribution of ions, particularly sodium (Na+) and potassium (K+), and the selective permeability of the membrane, which is primarily controlled by ion channels and pumps.

5 Must Know Facts For Your Next Test

1. The resting potential is mainly established by the sodium-potassium pump, which moves 3 Na+ ions out of the neuron for every 2 K+ ions it brings in.
2. The inside of the neuron is negatively charged compared to the outside due to a higher concentration of negatively charged proteins and the movement of potassium ions.
3. Resting potential can be influenced by factors like temperature, ion concentration gradients, and membrane permeability to different ions.
4. During resting potential, most voltage-gated ion channels are closed, preventing significant ion movement across the membrane.
5. Changes in resting potential can lead to hyperpolarization or depolarization, affecting the neuron's ability to fire an action potential.

Review Questions

• How does the sodium-potassium pump contribute to maintaining resting potential?
  • The sodium-potassium pump is essential for maintaining resting potential by actively transporting sodium (Na+) ions out of the neuron while bringing potassium (K+) ions in. This creates a concentration gradient where Na+ is higher outside and K+ is higher inside the neuron. As a result, the inside of the neuron becomes negatively charged compared to the outside, helping to establish the resting potential around -70 mV.
• Discuss how ion channels affect resting potential and what happens when they open.
  • Ion channels significantly impact resting potential by controlling ion flow across the neuron's membrane. When certain channels open, such as potassium channels during repolarization, K+ ions flow out of the neuron, causing hyperpolarization. Conversely, if sodium channels open, Na+ ions rush into the neuron, leading to depolarization. This change in permeability alters the resting potential and is crucial for generating action potentials.
• Evaluate how changes in ion concentration outside a neuron might affect its resting potential and excitability.
  • Changes in ion concentration outside a neuron can greatly affect its resting potential and overall excitability. For instance, if extracellular sodium levels decrease, this can hinder depolarization during an action potential because there are fewer Na+ ions available to enter the neuron when sodium channels open. Similarly, increased potassium levels outside can reduce the driving force for K+ to leave the cell, potentially leading to depolarization. These alterations can make neurons less responsive or even unable to generate action potentials effectively.

Related terms

Action Potential:

A rapid change in electrical charge that occurs when a neuron sends a signal down its axon, resulting from the influx of Na+ ions followed by the efflux of K+ ions.

Ion Channels: Proteins that create pathways for specific ions to move across the cell membrane, crucial for establishing and changing resting potential and action potentials.

Sodium-Potassium Pump:

A membrane protein that actively transports Na+ out of the cell and K+ into the cell, playing a key role in maintaining the resting potential.