47. Muscle Systems

Which of the following statements regarding control of muscle tissue is/are correct? Select True or False for each statement. T/F All skeletal muscles are voluntary. T/F Cardiac muscle is involuntary. T/F Some smooth muscle tissues are voluntary and others are involuntary. T/F Parasympathetic and sympathetic neurons innervate skeletal, cardiac, and smooth muscle tissues.

A human's internal organs are protected mainly by the a. hydrostatic skeleton. b. axial skeleton. c. exoskeleton. d. appendicular skeleton.

In muscle cells, myosin molecules continue moving along actin molecules as long as a. ATP is present and troponin is not bound to Ca2+. b. ADP is present and tropomyosin is released from intracellular stores. c. ADP is present and the intracellular acetylcholine level is high. d. ATP is present and the intracellular Ca2+ concentration is high

During the contraction of a vertebrate skeletal muscle fiber, calcium ions a. break cross-bridges as a cofactor in hydrolysis of ATP. b. bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed. c. transmit action potentials from the motor neuron to the muscle fiber. d. spread action potentials through the T tubules.

Which of the following is critical to the function of most exoskeletons, endoskeletons, and hydrostatic skeletons? a. Muscles interact with the skeleton in antagonistic groups. b. Muscles attach to each of these types of skeleton via tendons. c. Muscles extend joints by pushing skeletal elements. d. Segments of the body or limbs are extended when paired muscles relax in unison.

How did data on sarcomere structure inspire the sliding-filament model of muscle contraction? Explain why the observation that muscle cells contain many mitochondria and extensive smooth endoplasmic reticulum turned out to be logical once the molecular mechanism of muscular contraction was understood.

Rigor mortis is the stiffening of a body after death that occurs when myosin binds to actin but cannot unbind. What prevents myosin from unbinding?

In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? Compare and contrast the structure and function of the three types of skeletal muscle fibers.

In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? Predict who would likely have a greater proportion of fast glycolytic fibers in their gastrocnemius (calf) muscle—an elite distance runner or an elite sprinter. Explain.

In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? Predict the effect of training for a marathon on the number of muscle cells in the gastrocnemius. Explain.

In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? To discover the relationship between muscle-fiber types and performance, researchers obtained tiny biopsies of the gastrocnemius of 14 elite distance runners, 18 trained but non-elite distance runners, and 19 untrained subjects. They categorized the fiber types as slow or fast. (At the time of the study, intermediate fibers had not been identified as a third type.) Some of their data are shown here (* means 𝑃<0.05; BioSkills 3). What conclusions can you draw from these data?

In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? The researchers looked more closely at the data within the group of elite runners. Although the mean proportion of slow fibers was 79 percent in this group, individual values ranged from 27 percent in one runner to 98 percent in another. How does this finding affect your interpretation of the relationship between athletic performance and muscle-fiber types?

In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? Imagine that Tigist Assefa is racing against a bird and a fish, each with the same mass as Assefa. Which organism would have the highest cost of locomotion during the race?