Critical and Creative Thinking Questions
1. Rigor mortis is a stiffening of all the muscles in the body that
occurs shortly after death. It happens when all the ATP in the
muscles gets used up. Explain how this stiffening occurs with
respect to aspects of the contraction cycle.
2. Drugs called calcium channel blockers help relax the walls of
arteries and veins, thereby lowering high blood pressure. How
does blocking a calcium channel cause the muscles of the
arteries and veins to relax?
3. The night before racing, most marathon runners eat meals that
are high in carbohydrates, like pasta. Explain how this “carbing
up" helps their muscles during the race.
4. Jim lifts a hand weight by moving his elbow and subsequently
lowers it. List the muscles involved in each motion and explain
which ones are the prime movers, antagonists, synergists, and
5. Celia is training to run a 10k race. She stretches and exercises
daily for months. Explain why she must stretch. What changes
will occur to the structure of her leg muscles as a result of her
What is happening in this picture?
Many athletes complain about soreness after
an extensive workout. Sometimes massage
W hat should athletes do before
exercise to prevent or m inim ize injury?
W hat biochem ical or physiological
aspects of m uscle contraction cause
m uscle soreness follow ing exercise?
(Check your answers in Appendix C.)
The first energy source used in a working muscle is
a. aerobic respiration
d. creatine phosphate
Use this figure to answer
2. This figure shows______ muscle tissue.
3. What are the structures indicated by the ? in the figure?
d. intercalated discs
4. The cells in the figure are capable of______ .
a. twitch only
c. fused tetanus
b. unfused tetanus
d. wave summation
188 CHAPTER 6
The Muscular System