Which description best defines the excitable gap in a reentrant circuit?

Which description best defines the excitable gap in a reentrant circuit?

• A. The refractory region
• B. The boundary between chambers
• C. The portion of tissue that can be excited
• D. The non-excitable zone

Answer: (C)

The excitable gap is the portion of tissue in a reentrant circuit that has recovered enough to be excited again when the circulating impulse arrives. As the wavefront travels, tissue behind it remains refractory (non-excitable), while the ahead tissue recovers and becomes excitable. That recovered, ready-to-fire segment is the excitable gap, and it allows the impulse to re-enter the loop and sustain the reentrant rhythm. The other options describe non-excitable or boundary areas, which don’t fit this concept.

The excitable gap is the portion of tissue in a reentrant circuit that has recovered enough to be excited again when the circulating impulse arrives. As the wavefront travels, tissue behind it remains refractory (non-excitable), while the ahead tissue recovers and becomes excitable. That recovered, ready-to-fire segment is the excitable gap, and it allows the impulse to re-enter the loop and sustain the reentrant rhythm. The other options describe non-excitable or boundary areas, which don’t fit this concept.