Cells maintain a low intracellular Na+ concentration and a high intracellular K+ concentration by sodium-potassium pump which is an example of:
The sodium-potassium pump is a classic example of active transport because it moves ions against their concentration gradients, using ATP. So the options are likely to be active transport, passive transport, facilitated diffusion, etc. The key here is that active transport requires energy, usually in the form of ATP. Passive processes don't need energy.
Now, the core concept is active transport. The pump uses the enzyme Na+/K+ ATPase to hydrolyze ATP, which provides the energy to move three sodium ions out and two potassium ions in. This creates the electrochemical gradient essential for nerve and muscle function.
For the correct answer explanation, I need to detail the mechanism involving the ATPase enzyme, the movement of ions, and the role in maintaining gradients. The wrong options would be passive processes like simple or facilitated diffusion, which don't use ATP. Also, maybe some other active transport types, but the sodium-potassium pump is a specific example of primary active transport, not secondary.
Clinical pearl: Remember that the sodium-potassium pump is crucial for action potentials. If it's inhibited (like by digitalis), it affects heart function. High-yield fact: Active transport requires ATP, while passive does not. Also, the pump's role in maintaining resting membrane potential is vital.
I need to structure this into the required sections. Make sure each part is concise and fits within the character limit. Check for medical accuracy, use correct terminology. Let me verify that the sodium-potassium pump is indeed primary active transport. Yes, because it directly uses ATP. Secondary active transport uses the gradient created by primary transport, like in symporters or antiporters.
So the correct answer is active transport. The options are probably A to D with one being active transport. The user's correct answer line is missing the letter, but I can infer it's likely option C or D. Wait, the user's correct answer field is empty. But the question is about the sodium-potassium pump being an example of which transport type. So the correct answer is active transport, so the explanation should reflect that. The options might have active transport as one of them. Let me proceed to write the explanation with this in mind.
**Core Concept**
The sodium-potassium pump (Na⁺/K⁺-ATPase) is a primary active transport mechanism that uses ATP hydrolysis to move ions against their concentration gradients. It maintains electrochemical gradients critical for nerve impulse transmission and cellular homeostasis.
**Why the Correct Answer is Right**
The pump actively transports 3 Na⁺ ions out of the cell and 2 K⁺ ions into the cell for each ATP molecule hydrolyzed. This process is **primary active transport** because it directly consumes ATP to drive ion movement against their gradients. The enzyme Na⁺/K⁺-ATPase undergoes conformational changes, with phosphorylation from ATP enabling the pump to "toggle" between extracellular and intracellular configurations. These gradients are essential for resting membrane potential and secondary active transport processes.
**Why Each Wrong