You are holding a small textbook in your hand, and you begin to flex your elbow to raise the book. You stop with your elbow flexed at about 90 degrees, and the book held out in front of you. What is occurring in your biceps muscle at this time? A) your biceps is in a state of unfused tetanus B) your biceps is latched C) Ca²⁺ is elevated in biceps muscle fibers D) both your biceps is in a state of unfused tetanus AND Ca²⁺ is elevated in biceps muscle fibers E) both your biceps is latched AND Ca²⁺ is elevated in biceps muscle fibers

Question

Quizplus · Accepted Answer

When you flex your elbow and hold the textbook out in front of you, your biceps muscle is contracting, but not fully tetanic (unfused tetanus). At the same time, the concentrations of Ca^{2 and} are elevated in the biceps muscle fibers, indicating increased activation and utilization of the muscle. Therefore, choice D is the best answer. Choice A is incorrect because the biceps is not in a fully tetanic state. Choice B is not a known physiological term. Choice C does not provide enough information to make a conclusion. Choice E is incorrect because the term "latched" is not a known physiological term.

You Are Holding a Small Textbook in Your Hand, and You