MSCI520 cellular physiology quiz Liberty FALL 2023

Question 1 1 / 1 pts Which of these is not a characteristic of an action potential? Each normal action potential for a given cell type looks identical, depolarizes to the same potential, and repolarizes back to the same resting potential. An action potential at one site causes depolarization at adjacent sites, bringing those adjacent sites to threshold. If an excitable cell is depolarized to threshold in a normal manner, then the occurrence of an action potential is inevitable. On the other hand, if the membrane is not depolarized to threshold, no action potential can occur. Action potentials always occur following an increased conductance of chloride ions. Question 2 1 / 1 pts Which of these statements about refractory period is not true? During the refractory periods, excitable cells are incapable of producing normal action potentials The basis for the absolute refractory period is closure of the inactivation gates of the Na + channel in response to depolarization. The basis for the relative refractory period is the higher K + conductance than is present at rest. Because the membrane potential is closer to the K + equilibrium potential, more inward current is needed to bring the membrane to threshold for the next action potential to be initiated. When a nerve or muscle cell is depolarized rapidly, the usual threshold potential may lead to an action potential having been fired. This process is called accommodation.