Question

Depolarization of axolemma during nerve conduction takes place because

• A. equal amount of $N{a}^{+}\&K^{+}$ move out across axolemma
• B. $N{a}^{+}$ move inside & more $K^{+}$ move outside
• C. more $N{a}^{+}$ moves outside than $K^{+}$ moving outside
• D. none of these

Answer 1

The correct option is B

$N{a}^{+}$ move inside & more $K^{+}$ move outside

At rest, the axonal membrane is more permeable to potassium ions and impermeable to sodium ions. Axoplasm contains negatively charged proteins and potassium ions while outside the axonal membrane there is a higher concentration of positively charged sodium ions creating a concentration gradient across the membrane. This is called resting potential. When an impulse is recieved, it alters the membrane permability and $N{a}^{+}$ moves inside through channels and K moves out causing an action potential.