Q. An action potential in the nerve fibre is produced when positive and negative charges on outside and the inside of the axon membrane are reversed because
A) More potassium ions enter the axon as compared to sodium ions leaving it
B) More sodium ions enter the axon as compared to potassium ions leaving it
C) All potassium ions leave the axon
D) All sodium ions enter the axon
Explanation
When a nerve fibre is stimulated, its membrane becomes more permeable to sodium ions, hence, more sodium ions enter the axon than potassium ions leaving it. As a result, the positive and negative charges on the outside and inside of the membrane are reversed. The membrane with reversed polarity is called depolarized.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.