Once an action potential is triggered, there is a: A. reversal of the membrane polarity, with the interior of the cell becoming positively charged B. reversal of the membrane polarity, with the interior of the cell becoming negatively charged C. sudden rush of potassium into the neuron D. sudden impermeability of the membrane to the transport of ions

(A) A reversal of the membrane polarity, with the interior of the cell becoming positively charged

A. reversal of the membrane polarity, with the interior of the cell becoming positively charged.

Explanation:

Nerve impulses are generated due to the reversal of the polarity between the intra and extracellular domains of the neural membrane. At rest, when no nerve impulse is traveling through the neuron, its membrane is at resting potential i. e. the outside of the membrane is positively charged due to abundance of sodium (Na+) ions. The inside of the membrane is negatively charged due to two reasons: 1. lesser concentration of cations (K+) inside the cell as compared to outside. 2. Abundance of chloride ions. At resting potential, the Na+/K + pumps in the neuron membrane is closed, inhibiting the movement of these two ions. Upon arrival of a stimulus, these Na+/K + pumps open, Na + ions flood inside the cell, giving a positive charge to the inside of the membrane. Simultaneously, the K + ions rush outside. Abundance of Cl - ions outside the cell gives the outer membrane a negative charge. These physiological changes generate an action potential that carries the nerve impulse forward.