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PART 2 Support and Movement

Choose the conditions that occur in both physiological contractureand rigor mortis.a. 1,2,3 c. 1,2,3,4 e. 1,2,3,4,5b. 1,2,5 d. 1,2,4,5

20. Jerry Jogger’s 3-mile run every morning takes about 30 minutes.Which of these sources provides most of the energy for his run?a. aerobic respiration c. creatine phosphateb. anaerobic respiration d. stored ATP

21. Which of these conditions would you expect to find within the legmuscle fibers of a world-class marathon runner?a. myoglobin-poor c. primarily anaerobicb. contract very quickly d. numerous mitochondria

22. Which of these increases the least as a result of muscle hypertrophy?a. number of sarcomeres d. blood vessels and mitochondriab. number of myofibrils e. connective tissuec. number of fibers

23. Relaxation in smooth muscle occurs whena. myosin kinase attaches phosphate to the myosin head.b. Ca 2+ binds to calmodulin.

c. myosin phosphatase removes phosphate from myosin.d. Ca 2+ channels open.e. Ca 2+ is released from the sarcoplasmic reticulum.

24. Compared with skeletal muscle, visceral smooth musclea. has the same ability to be stretched.b. loses the ability to contract forcefully when stretched.c. maintains about the same tension, even when stretched.d. cannot maintain long, steady contractions.e. can accumulate a substantial oxygen deficit.

25. Which of these statements concerning aging and skeletal muscle is correct?a. A loss of muscle fibers occurs with aging.b. Slow-twitch fibers decrease in number faster than fast-twitch fibers.c. The loss of strength and speed is due mainly to loss of neuromus-cular junctions.d. The density of capillaries in skeletal muscle increases.e. The number of motor neurons remains constant.

Answers in appendix E

1. Bob Canner improperly canned some homegrown vegetables. Aftereating the vegetables, he contracted botulism poisoning with symp-toms that included difficulty swallowing and breathing. Eventually,he died of respiratory failure (his respiratory muscles relaxed andwould not contract). Assuming that botulism toxin affects the neu-romuscular junction, propose the ways that the toxin produces theobserved symptoms.2. A patient is thought to be suffering from either muscular dystrophyor myasthenia gravis. How would you distinguish between the twoconditions?3. Design an experiment to test the following hypothesis: Muscle A hasthe same number of motor units as muscle B. (Assume that you canstimulate the nerves that innervate skeletal muscles with an electronicstimulator and monitor the tension produced by the muscles.)4. Explain what is happening at the level of individual sarcomeres whena person is using his or her biceps brachii muscle to hold a weight ina constant position. Contrast this with what is happening at the levelof individual sarcomeres when a person lowers the weight, as well aswhen he or she raises the weight.5. Predict the shape of an active tension curve for visceral smooth muscle.How does it differ from the active tension curve for skeletal muscle?6. A researcher is investigating the composition of muscle tissue in thegastrocnemius muscles (in the calf of the leg) of athletes. She takesa needle biopsy from the muscle and determines the concentration(or enzyme activity) of several substances. Describe the major differ-ences this researcher sees when comparing the muscles of athleteswho perform in the following events: 100-meter dash, weight lifting,and 10,000-meter run.

7. Shorty McFleet noticed that his rate of respiration was elevated afterrunning a 100-meter race but was not as elevated after running slowlyfor a much longer distance. How would you explain this?8. High blood K + concentrations cause depolarization of the restingmembrane potential. Predict and explain the effect of high blood K + levels on smooth muscle function.9. Predict and explain the response if the ATP concentration in a musclethat was exhibiting rigor mortis could be instantly increased.10. A hormone stimulates the smooth muscle of a blood vessel to con-tract. Although the hormone causes a small change in membranepotential, the smooth muscle contracts substantially. Explain.11. Experiments were performed in an anatomy and physiology labora-tory. First, the rate and depth of respiration for a resting student weredetermined. In experiment A, students ran in place for 30 seconds,immediately sat down and relaxed, and then had their respiration rateand depth measured. Experiment B was conducted in the same man-ner as experiment A, except that the students held their breath whilerunning in place. What differences in respiration would you expectfor the two experiments? Explain the basis for your predictions.12. After learning about muscle fiber types in his anatomy and physiol-ogy class, Alex started to notice differences in the color of the turkeymeat he ate for lunch. Some of the meat was very white and someof it was much darker. From the color of the meat, Alex guessedwhich muscles the bird used for maintenance of posture and/or slowmovements, such as walking, and which muscles it used for quickermovements, such as running or flying. What type of muscle fiberpredominates in white meat? In dark meat? Explain how the colorof the meat relates to the function of the muscle.

Answers in appendix F