Which term refers to the phase when the heart is in a ready state to contract?

• A. Polarization
• B. Depolarization
• C. Repolarization
• D. Ischemia

Answer: (A)

The phase in which heart muscle cells are ready to contract is polarization—the resting state where the inside of the cell is negatively charged relative to the outside. This resting potential sets the stage so that a forthcoming electrical impulse can trigger depolarization, opening channels and starting the contraction process. After depolarization and the ensuing contraction, cells return to this resting polarized state through repolarization, resetting for the next beat. Ischemia is not part of this normal cycle; it refers to reduced blood flow and can disrupt electrical activity.