Na+ channels are [a] because they allow [b] ions into the ce…

Na+ channels are [a] because they allow [b] ions into the cell depolarizing the membrane and driving it [c] the the threshold (firing) potential. Cl- channels are [d] because they allow [e] ions into the cell making it [f] for the membrane to depolarize. K+ channels are [g] because they allow [h] ions out of the cell making it [i] for the membrane to depolarize.