NMDA receptors ___________ when the nearby membrane is not depolarized.
A) allow both sodium and calcium to enter the cell
B) are blocked by a molecule of calcium
C) are blocked by a molecule of magnesium
D) allow potassium to leave the cell

Question

Quizplus · Accepted Answer

NMDA receptors are blocked by a magnesium ion at resting membrane potential. It is only when the membrane is depolarized that the magnesium ion moves out of the channel, allowing calcium and some sodium ions to enter the cell. This activation of NMDA receptors is required for certain forms of synaptic plasticity and learning.

NMDA Receptors ___________ When the Nearby Membrane Is Not Depolarized