What occurs during depolarization of a cardiac cell?

What occurs during depolarization of a cardiac cell?

• A. The inside of the cell becomes more negative
• B. The inside of the cell becomes more positive
• C. The cell is unable to respond to any stimulus
• D. The cell returns to its resting membrane state

Answer: (B)

During depolarization of a cardiac cell, the inside of the cell becomes more positive. This process begins when sodium channels open in response to a stimulus, allowing sodium ions (Na+) to rush into the cell. As positively charged sodium ions enter, the internal membrane potential shifts from its resting state, which is typically negative, towards a more positive value. This rapid influx of positive charges is what characterizes depolarization. The importance of depolarization in cardiac cells cannot be overstated; it is a critical step in the cardiac action potential and in initiating the contraction of the heart muscle. Following depolarization, the cell will eventually repolarize, returning to its resting membrane potential, but this occurs after the depolarization phase. Thus, understanding depolarization is essential for grasping how heart contractions are triggered and controlled.

During depolarization of a cardiac cell, the inside of the cell becomes more positive. This process begins when sodium channels open in response to a stimulus, allowing sodium ions (Na+) to rush into the cell. As positively charged sodium ions enter, the internal membrane potential shifts from its resting state, which is typically negative, towards a more positive value. This rapid influx of positive charges is what characterizes depolarization.

The importance of depolarization in cardiac cells cannot be overstated; it is a critical step in the cardiac action potential and in initiating the contraction of the heart muscle. Following depolarization, the cell will eventually repolarize, returning to its resting membrane potential, but this occurs after the depolarization phase. Thus, understanding depolarization is essential for grasping how heart contractions are triggered and controlled.