Depolarizes

Depolarizes is the third-person singular present tense form of the verb depolarize. Depolarize means to reduce or remove polarization in a system, in particular to move a membrane potential toward a less negative value or toward zero.

In biology, depolarization refers to a change in a cell’s membrane potential toward a more positive value. In excitable cells such as neurons and muscle fibers, depolarization is usually caused by the opening of voltage-gated sodium channels, leading to an inward Na+ current and a rapid rise in membrane potential. This change can trigger an action potential and, in neurons, propagate electrical signals; in cardiac tissue it contributes to the initiation of contraction. The depolarization phase is typically followed by repolarization, when potassium exits the cell and the membrane potential returns toward the resting level.

In electrocardiography, atrial depolarization creates the P wave, while ventricular depolarization corresponds to the QRS complex. The timing and magnitude of these depolarization events reflect the activity and coordination of the heart’s electrical system.

In physics and materials science, depolarization describes the loss or reduction of net polarization in a dielectric or ferroelectric material. This can occur due to heating, exposure to alternating electric fields, or the relaxation of aligned domains, reducing the material’s polarization. In ferroelectrics, depolarization can be influenced by thermal agitation near a Curie point or by external fields that oppose the polarization, diminishing remnant polarization.