Which statement best describes the excitable gap in a reentrant circuit?

Which statement best describes the excitable gap in a reentrant circuit?

• A. It is the refractory tissue
• B. It is the part of the circuit that is ready to be excited
• C. It is the tissue with maximal conduction
• D. It is a boundary zone only

Answer: (B)

In a reentrant circuit, the excitable gap is the portion of tissue that has recovered from refractoriness and is ready to be excited by the circulating impulse. The wave travels around the loop, but tissue behind the wavefront is refractory and cannot be reactivated immediately. For the loop to continue, the next segment of tissue ahead must be excitable when the wavefront arrives, creating an open, receptive segment—the excitable gap. It’s not about tissue that is currently refractory, nor about the speed of conduction, nor merely a boundary zone; it’s the part of the circuit that is ready to respond to the incoming impulse.

In a reentrant circuit, the excitable gap is the portion of tissue that has recovered from refractoriness and is ready to be excited by the circulating impulse. The wave travels around the loop, but tissue behind the wavefront is refractory and cannot be reactivated immediately. For the loop to continue, the next segment of tissue ahead must be excitable when the wavefront arrives, creating an open, receptive segment—the excitable gap. It’s not about tissue that is currently refractory, nor about the speed of conduction, nor merely a boundary zone; it’s the part of the circuit that is ready to respond to the incoming impulse.