The duration of action potential of contractile myocardium is _________.  Question 5Answera.Similar to skeletal muscle b.Prolongedc.Shortd.Variable

To answer the question regarding the duration of action potentials in contractile myocardium, we need to analyze the characteristics of myocardial cells compared to skeletal muscle cells.

1. Understanding the Action Potential: The action potentials in cardiac muscle (myocardium) have a longer duration compared to those in skeletal muscle. This prolonged duration is critical for the function of the heart as it allows for the entire heart muscle to contract and then relax, which is essential for effective pumping.

2. Comparison with Skeletal Muscle: In skeletal muscle, the action potential duration is quite short (approximately 1-2 milliseconds), which allows for rapid twitches. However, in the myocardium, especially in the ventricles, the action potential can last from 200 to 300 milliseconds due to the plateau phase caused by calcium ion influx.

3. Conclusion: Given that action potentials in contractile myocardium are indeed prolonged relative to those in skeletal muscle, the correct answer is:

Final Answer: b. Prolonged