An experimental toxin makes the refractory period of cardiac muscle cells equal in length to that of skeletal muscle fibers. Predict the consequences of this toxin. (Connects to Chapter 10)

Video transcript

Hi, everybody. Welcome back. Our next question says, if the refractory period is shortened to match that of skeletal muscles, it may increase the risk of which of the following. A arrhythmias B hypertension C cardiomyopathy or D pericarditis. So let's recall what refractory period is, which is that it's that time after an action potential where cells cannot respond to a second stimulus. So it affects the timing of response to stimuli. So when we think about time and muscle contraction in the heart, we think about the rhythm of the heart, the rhythm of the heartbeat. So when we look at our answer choices and think what would be the consequence if we shortened the refractory period of the cardiac muscle tissue? Well, the answer is a arrhythmias. And as we can even tell by just looking at the word with that prefix, a arrhythmia, that would be an irregular heart rate if that refractory period is shortened and the cells can respond quicker. We have this increased excitability of the cardiac tissue which can throw off that heart rate and cause all sorts of problems cause it to go too fast, too slow or just that sensation of skipping a beat and that can go on to further damage the heart. When we look at our other answer. Choices B, hypertension hypertension is uh elevated blood pressure. So not what we're talking about doesn't have anything to do with the rhythm of the heart rate. So choice B, not correct TC cardiomyopathy is disease of the heart muscle. So, cardiomyopathy might cause an arrhythmia if the heart muscle is damaged and not responding correctly, but it's not the direct result of refractory period. Shortening. So choice c not correct. And then finally, pericarditis, we have this suffix of itis meaning inflammation and that would be inflammation of the pericardium that thin fluid filled sac that surrounds the heart and protects it. But this wouldn't be a direct consequence of shortening the refractory period. So trustee not correct. So once again, if you shorten the refractory period of cardiac muscle to make it map at a skeletal muscle, it may increase the risk of choice. A arrhythmias. See you in the next video.