Neuroscience: Resting Membrane Potential

Questions and Answers

Why is resting membrane potential important to how neurons signal one another?

Resting membrane potential is the voltage difference between the inside and outside of a neuron at rest. Changes in RMP are the basis for how neurons communicate, triggering an action potential which sends a signal to the brain.

How is resting membrane potential maintained?

The inside of the neuron is negatively charged relative to the outside, with a typical RMP of -65mV. Sodium-potassium pumps move two potassium ions inside the cell while pumping three sodium ions out, helping maintain the negatively charged membrane.

How is resting membrane potential measured?

The reference electrode sits in the bath to measure the potential outside. The recording electrode pierced into the neuron measures the potential difference between the inside and outside.

What are the three main players in the neuron?

Ions, membrane, and membrane proteins (ion channels and ion pumps). Signup and view all the answers

What are two physical forces that determine a neuron's resting potential?

Diffusion and electrical potential. Signup and view all the answers

What is the importance of the sodium-potassium pump?

It helps maintain resting potential by concentrating K+ inside and Na+ outside the cell using ATP to transport ions against their gradients. Signup and view all the answers

Why is the Ek relevant to the resting membrane potential?

At rest, membranes are mostly selectively permeable to K+, and when potassium channels are open, ions flow, bringing the membrane potential closer to the equilibrium of that ion. Signup and view all the answers

What happens to the membrane potential when the brain is deprived of oxygen?

Cellular respiration will not produce ATP, leading to the failure of sodium-potassium pumps and the loss of resting membrane potential. Signup and view all the answers

When do you use Nernst equation vs when do you use Goldman equation?

Nernst equation calculates the equilibrium potential of a single ion, while Goldman equation calculates the resting membrane potential of a whole neuron. Signup and view all the answers

Why doesn't RMP exactly match Ek?

The membrane is primarily permeable to K+ but also semi-permeable to Na+, which causes the RMP to differ from Ek. Signup and view all the answers

How does altering the external and internal concentrations of various ions impact equilibrium potentials and the resting membrane potential?

High extracellular potassium levels reverse the chemical gradient, causing positive ions to move inside the cell, increasing the voltage and causing depolarization. Signup and view all the answers

At rest, what ions are more concentrated inside the membrane?

K+ and organic anions. Signup and view all the answers

At rest, what ions are more concentrated outside of the cell?

Cl- ions and Na+. Signup and view all the answers

Study Notes

Importance of Resting Membrane Potential

Resting membrane potential (RMP) allows neurons to signal each other through changes in voltage.
A change in RMP triggers an action potential, communicating signals to the brain.

Maintenance of Resting Membrane Potential

The typical RMP of a neuron is around -65 mV, indicating a negatively charged inside relative to outside.
Sodium-potassium pumps are crucial, moving 2 potassium ions inside and 3 sodium ions outside to maintain this negative charge.

Measurement of Resting Membrane Potential

RMP is measured using a reference electrode placed in the bath and a recording electrode inserted into the neuron.
A reading of -60 mV means the inside of the neuron is 60 mV more negative than the outside.

Main Components of Neurons

Ions in extracellular fluid are essential for resting and action potentials.
Neuron membrane consists of phospholipids and membrane proteins responsible for ion movement:
- Ion channels, selectively allowing specific ions to pass; some are gated by voltage.
- Ion pumps requiring ATP for transporting ions across the membrane.

Physical Forces Influencing Resting Potential

Diffusion drives ions from high to low concentration; Na+ enters cells when channels open due to higher concentration outside.
Electrical potential causes ions to flow towards opposite charges; Na+ is drawn into negatively charged cells.

Role of Sodium-Potassium Pumps

Sodium-potassium pumps maintain resting potential by keeping potassium inside and sodium outside the neuron.
These pumps use ATP to transport 3 Na+ out and 2 K+ in against their gradients.

Relevance of Equilibrium Potential (Ek)

The membrane is selectively permeable to K+ at rest, aligning the membrane potential closer to Ek.
Open potassium channels allow K+ to flow, affecting overall membrane potential.

Impact of Oxygen Deprivation

Lack of oxygen halts ATP production, impairing sodium-potassium pumps.
Failure of these pumps results in the loss of resting membrane potential.

Nernst vs. Goldman Equation

The Nernst equation calculates the equilibrium potential for a single ion.
The Goldman equation calculates the overall resting membrane potential for the neuron.

Difference Between RMP and Ek

RMP does not exactly match Ek due to the membrane's selective permeability to both K+ and Na+.

Effects of Altered Ion Concentrations

Increased extracellular potassium can reverse the chemical gradient, leading to depolarization as positive ions enter the cell.

Ions Inside the Neuron at Rest

At rest, higher concentrations of K+ and organic anions are found inside the neuron.

Ions Outside the Cell at Rest

Elevated levels of Cl- and Na+ ions are present outside the neuron at rest.

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Description

This quiz delves into the concept of resting membrane potential (RMP) in neurons, its significance in neural signaling, and its maintenance mechanisms. Participants will explore how voltage changes lead to action potentials, and the role of ion channels and pumps in maintaining RMP.