Resting potential

Definition

Resting potential is the electrical charge difference across the membrane of a neuron when it is not actively transmitting a signal. This potential is primarily established by the distribution of ions, particularly sodium and potassium, across the membrane and is critical for the generation of action potentials, which allow neurons to communicate with each other.

5 Must Know Facts For Your Next Test

1. Resting potential typically ranges from -60 to -70 millivolts, indicating that the inside of the neuron is negatively charged relative to the outside.
2. The sodium-potassium pump actively transports three sodium ions out of the neuron and two potassium ions into the neuron, maintaining the concentration gradient essential for resting potential.
3. At resting potential, potassium ions can diffuse more freely than sodium ions due to a higher permeability of the neuronal membrane to potassium.
4. Any change in resting potential can lead to a depolarization or hyperpolarization of the neuron, influencing its ability to generate action potentials.
5. Resting potential is crucial for the excitability of neurons, as it sets the stage for rapid changes in membrane potential necessary for signal transmission.

Review Questions

• How does the distribution of sodium and potassium ions contribute to establishing resting potential?
  • The resting potential is primarily determined by the uneven distribution of sodium and potassium ions across the neuronal membrane. The sodium-potassium pump actively transports sodium ions out of the neuron while bringing potassium ions in. As a result, there are more potassium ions inside compared to outside, leading to a net negative charge inside the neuron. This ion concentration gradient is essential for maintaining the resting potential and preparing the neuron for action potential generation.
• What role do ion channels play in modifying resting potential and influencing neuronal excitability?
  • Ion channels are crucial for modifying resting potential and affecting neuronal excitability. They facilitate the movement of specific ions across the neuronal membrane based on their concentration gradients. At resting potential, potassium ion channels are more permeable, allowing potassium to flow out, which maintains negativity inside. When ion channels for sodium open during depolarization, they enable sodium influx, disrupting resting potential and leading to action potentials. Thus, ion channels play a central role in both establishing and altering resting potential.
• Evaluate how alterations in resting potential can impact neuronal signaling and communication.
  • Alterations in resting potential can significantly impact neuronal signaling and communication by affecting a neuron's ability to generate action potentials. For instance, if a neuron's resting potential becomes less negative (depolarization), it may become easier to reach the threshold required for an action potential. Conversely, hyperpolarization makes it harder for a neuron to fire. These changes can influence everything from reflexes to complex behaviors by altering how neurons communicate within neural circuits, ultimately affecting responses to stimuli and information processing in the nervous system.

Related terms

action potential:

A rapid change in membrane potential that occurs when a neuron sends information down its axon, triggered by reaching a threshold level of depolarization.

neuron:

A specialized cell that transmits nerve impulses, consisting of a cell body, dendrites, and an axon.

ion channels:

Proteins in the cell membrane that allow specific ions to enter or exit the neuron, crucial for establishing resting potential and generating action potentials.