Resting Membrane Potential

Definition

Resting membrane potential refers to the electrical charge difference across a cell membrane when the cell is not actively sending signals. This potential is crucial for maintaining the stability of the cell's environment, allowing for the proper functioning of neurons and muscle cells, and plays a significant role in the processes of action potentials and signal transmission.

5 Must Know Facts For Your Next Test

1. The typical resting membrane potential for most neurons ranges from -60 mV to -70 mV, indicating a negative charge inside relative to outside.
2. Potassium ions (K+) are more concentrated inside the cell, while sodium ions (Na+) are more concentrated outside, which creates a concentration gradient critical for resting membrane potential.
3. The resting membrane potential is largely influenced by the permeability of the membrane to potassium ions due to open potassium channels.
4. Changes in resting membrane potential can lead to excitability in neurons, affecting their ability to generate action potentials.
5. The maintenance of resting membrane potential is vital for cellular homeostasis and overall cell function, influencing processes like neurotransmission and muscle contraction.

Review Questions

• How does the concentration gradient of sodium and potassium ions contribute to the resting membrane potential?
  • The concentration gradient of sodium (Na+) and potassium (K+) ions is fundamental to establishing resting membrane potential. Potassium ions are more concentrated inside the cell, while sodium ions are more concentrated outside. When the cell is at rest, potassium channels are more permeable than sodium channels, allowing K+ to flow out of the cell. This movement contributes to a negative charge inside the cell, resulting in a typical resting membrane potential around -70 mV.
• Discuss the role of ion channels and the sodium-potassium pump in maintaining resting membrane potential.
  • Ion channels and the sodium-potassium pump work together to maintain resting membrane potential. The sodium-potassium pump actively transports 3 Na+ ions out of the cell while bringing 2 K+ ions into it, using ATP for energy. This action creates a concentration gradient that keeps sodium levels low inside and potassium levels high. Additionally, ion channels allow K+ to move out more freely than Na+ can enter, which helps keep the inside of the cell negatively charged relative to the outside.
• Evaluate how alterations in resting membrane potential can impact neuronal excitability and signal transmission.
  • Alterations in resting membrane potential can significantly impact neuronal excitability and signal transmission. If the resting membrane potential becomes less negative (depolarization), it increases the likelihood that a neuron will reach threshold and generate an action potential. Conversely, hyperpolarization makes it harder for a neuron to fire because it pushes the resting potential further away from threshold. These changes affect how effectively neurons communicate with each other and with muscles, influencing everything from reflexes to complex behaviors.

Related terms

Action Potential: A rapid change in membrane potential that occurs when a neuron or muscle cell is activated, leading to the transmission of an electrical signal.

Ion Channels: Proteins in the cell membrane that allow specific ions to enter or exit the cell, playing a key role in establishing and maintaining resting membrane potential.

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