Resting Potential

Definition

Resting potential refers to the electrical charge difference across a cell membrane when a neuron is not actively transmitting a signal, typically around -70 mV in neurons. This state is crucial as it establishes the baseline for generating action potentials, allowing for the rapid communication of signals in the nervous system. The resting potential is maintained by the selective permeability of the membrane and the activity of ion pumps, particularly the sodium-potassium pump.

5 Must Know Facts For Your Next Test

1. Resting potential is primarily established by the uneven distribution of ions, especially sodium (Na+) and potassium (K+), across the neuron's membrane.
2. The sodium-potassium pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, contributing to the negative charge inside the neuron at rest.
3. Resting potential is essential for a neuron's ability to fire action potentials, as it allows for a rapid influx of Na+ when a stimulus occurs.
4. Factors like temperature, ion concentrations, and permeability of the membrane can affect resting potential.
5. While -70 mV is typical for neurons, different types of cells may have varying resting potentials based on their specific ion channels and pumps.

Review Questions

• How does resting potential set the stage for action potentials in neurons?
  • Resting potential creates an electrochemical gradient that is vital for action potentials. When a neuron is at resting potential, it is polarized with a negative interior compared to the outside. This polarization allows for rapid depolarization when sodium channels open in response to a stimulus, leading to an action potential. Without a proper resting potential, neurons wouldn't be able to generate action potentials efficiently.
• Discuss how ion channels contribute to maintaining resting potential in neurons.
  • Ion channels play a crucial role in maintaining resting potential by controlling the movement of specific ions across the neuronal membrane. Potassium channels are particularly important because they allow K+ ions to flow out of the neuron, contributing to its negative internal charge. Additionally, sodium channels remain mostly closed at rest, preventing Na+ from entering. This selective permeability helps maintain the balance needed for resting potential.
• Evaluate the impact of alterations in ion concentrations on resting potential and neuronal function.
  • Changes in ion concentrations can significantly affect resting potential and overall neuronal function. For instance, an increase in extracellular potassium levels can reduce the resting potential (making it less negative), leading to excitability issues or altered signaling. Conversely, a decrease in sodium concentration can hinder action potential generation. Such alterations can have wide-ranging effects on nerve signal transmission, affecting everything from muscle contraction to reflexes.

Related terms

Action Potential: A rapid change in membrane potential that occurs when a neuron fires, characterized by depolarization followed by repolarization.

Ion Channels: Protein structures that allow specific ions to pass through the cell membrane, playing a key role in establishing and altering membrane potentials.

Nernst Equation:

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