NEET2008ZoologyNeural Control and CoordinationActual
During the propagation of a nerve impulse, the action potential results from the movement of
Options
- AK ⁺ ions from extracellular fluid to intracellular fluid
- BNa ⁺ ions from intracellular fluid to extracellular fluid
- CK ⁺ ions from intracellular fluid to extracellular fluid
- DNa ⁺ ions from extracellular fluid to intracellular fluid
Correct answer
D. Na ⁺ ions from extracellular fluid to intracellular fluid
Step-by-step solution
During the propagation of nerve impulse when a stimulus of adequate strength is applied to a polarised membrane, the permeability of the membrane to Na ⁺ is greatly increased at the point of stimulation. As a result the sodium ion channels permit the influx of Na ⁺ by diffusion. Since, there are more Na ⁺ ions entering than leaving, the electrical potential of the membrane changes from -70 mV towards zero. At 0 mV the membrane is said to be depolarised. While the resting potential is determined largely by K ⁺ ions,