Biology – 3.3 Active transport | e-Consult
3.3 Active transport (1 questions)
Nerve cells (neurons) maintain a resting potential, a difference in electrical charge across their cell membrane. This potential is crucial for the transmission of nerve impulses. The sodium-potassium pump is a key component in establishing and maintaining this resting potential, and it relies on active transport.
The Role of the Sodium-Potassium Pump:
- Pump Mechanism: The sodium-potassium pump is a transmembrane protein that uses ATP to transport sodium ions (Na+) out of the neuron and potassium ions (K+) into the neuron.
- Concentration Gradients: At rest, there is a higher concentration of Na+ outside the neuron and a higher concentration of K+ inside the neuron.
- ATP Requirement: The pump requires ATP to move these ions against their respective concentration gradients. It pumps 3 Na+ ions out for every 2 K+ ions pumped in.
- Resting Potential Establishment: The outward movement of Na+ creates a net negative charge inside the neuron, contributing to the resting potential. The inward movement of K+ further reinforces this negative charge.
Active Transport Involvement:
The sodium-potassium pump is a prime example of active transport. It requires energy (ATP) to move ions against their concentration gradients. Without the continuous action of the sodium-potassium pump, the concentration gradients of Na+ and K+ would dissipate, and the resting potential would be lost. This would prevent the neuron from being able to generate and transmit nerve impulses. The pump constantly works to maintain the correct ionic balance across the neuronal membrane, ensuring the neuron is ready to fire.