How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study General physiology: excitability and potassium?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.

General physiology MCQ (B7-PHYS1-7)

Q: What is the answer to this Physiology question?

The best answer is A, The resting potential becomes less negative, so Na+ channels inactivate and excitability falls. Raising extracellular K+ reduces the K+ gradient and shifts the K+ equilibrium potential and resting potential toward zero.

Q: What concept does this question test?

It tests General physiology: excitability and potassium in Physiology. Sustained partial depolarisation inactivates voltage-gated Na+ channels, so action potentials cannot be generated normally and flaccid weakness results; cardiac conduction is similarly affected.

Try it

Physiology · General physiology: excitability and potassium

Sample item

A 60-year-old man with renal failure has serum potassium of 7.2 mmol/L and generalised muscle weakness. Which mechanism explains the weakness?

AThe resting potential becomes less negative, so Na+ channels inactivate and excitability fallsBExtracellular K+ blocks acetylcholine release from the motor nerve terminalCExtracellular K+ directly inhibits Ca2+ release from the sarcoplasmic reticulumDThe K+ equilibrium potential becomes more negative, so the membrane hyperpolarises and cannot reach threshold

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. The resting potential becomes less negative, so Na+ channels inactivate and excitability falls

Raising extracellular K+ reduces the K+ gradient and shifts the K+ equilibrium potential and resting potential toward zero. Sustained partial depolarisation inactivates voltage-gated Na+ channels, so action potentials cannot be generated normally and flaccid weakness results; cardiac conduction is similarly affected.

Option by option

A. The resting potential becomes less negative, so Na+ channels inactivate and excitability falls (correct)
Persistent depolarisation inactivates Na+ channels, leaving the cell less excitable.
B. Extracellular K+ blocks acetylcholine release from the motor nerve terminal
Hyperkalaemia does not impair acetylcholine release; it acts on the excitable membrane itself.
C. Extracellular K+ directly inhibits Ca2+ release from the sarcoplasmic reticulum
Potassium has no direct effect on sarcoplasmic reticulum Ca2+ release.
D. The K+ equilibrium potential becomes more negative, so the membrane hyperpolarises and cannot reach threshold
Hyperpolarisation is the effect of hypokalaemia, which also causes weakness through a different route.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

General physiology: excitability and potassium: practice question

Try it

The answer and the reasoning

Option by option

More Physiology questions

Questions about this Physiology question