The movement of sodium (Na⁺) and potassium (K⁺) ions across the cell membrane is essential for maintaining the resting membrane potential in neurons. Let’s break it down:
Resting Membrane Potential:
- A resting neuron has a voltage across its membrane called the resting membrane potential (or simply, resting potential).
- This potential difference is measured relative to the outside of the cell, and it typically ranges from about -30 mV to -90 mV.
- The inside of the cell is more negative than the outside due to the separation of charge.
Sodium-Potassium Pump:
- The sodium-potassium pump (Na⁺-K⁺ pump) is a protein embedded in the cell membrane.
- It actively transports sodium ions out of the cell and potassium ions into the cell.
- For every molecule of ATP that’s broken down, the pump moves:
- Three sodium ions (Na⁺) from the inside to the outside of the cell.
- Two potassium ions (K⁺) from the outside to the inside of the cell.
Why This Matters:
- The sodium-potassium pump helps maintain the negatively charged membrane inside the cell.
- It contributes to the resting potential by establishing concentration gradients for Na⁺ and K⁺.
- The resting potential is close to the equilibrium potential of K⁺ because the membrane is more permeable to K⁺ than Na⁺.
In summary, the sodium-potassium pump plays a crucial role in maintaining the resting membrane potential, which is essential for proper neuronal function. It ensures that the right balance of ions is maintained inside and outside the cell123. 🧠🔍