Practice question · Multiple choice
The sodium-potassium pump runs constantly in every neuron, and the brain spends a large share of its entire energy budget on it. What is all that ATP buying?
Hints
- The neuron is doing nothing observable. Ask what it would have to do first if it were suddenly asked to fire.
- A spike costs almost nothing to fire, because the gradients were paid for in advance.
Show the answer
D. A charged battery, whose gradients the action potential spends
Why
Rest is not idling, it is holding a charged battery. The pump pays in advance for gradients the spike then spends in a millisecond, which is why the brain burns roughly a fifth of the body's energy while apparently doing nothing. Readiness has a standing price.
Practise Resting Potential
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More questions on Resting Potential
- Sort each ion by where it is more concentrated across the membrane of a resting neuron.
- A neuron at rest sits at about −70 mV. Why is the membrane NOT electrically neutral at rest?
- Trace WHY the inside of the resting neuron ends up negative. Put the causal steps in order.
- A neuron's potassium equilibrium potential is about −90 mV, yet the membrane actually rests at about −70 mV.…
- Select every statement that is TRUE of the resting potential.