339
CHAPTER NINE
Muscular System
PART C
31
Label as many muscles as you can identify in these photos of a model whose muscles are enlarged by exercise. Describe the action of
each muscle identiF
ed. (pp. 306–334)
OUTCOMES 7.11, 9.8
1. Several important nerves and blood vessels course through
the muscles of the gluteal region. To avoid the possibility of
damaging such parts, intramuscular injections are usually
made into the lateral, superior portion of the gluteus medius.
What landmarks would help you locate this muscle in a
patient?
OUTCOMES 9.2, 9.3
2. Millions of people take drugs called statins to lower serum
cholesterol levels. In a small percentage of people taking these
drugs, muscle pain, termed myopathy, is an adverse effect. In a
small percentage of these individuals, the condition progresses
to rhabdomyolysis, in which the sarcolemma breaks down.
a. Describe the structure and state the function of the
sarcolemma.
b. Physicians can measure a patient’s levels of creatine
phosphokinase to track the safety of using a statin. Enzyme
INTEGRATIVE ASSESSMENTS / CRITICAL THINKING
levels that exceed 10 times normal indicate possible
rhabdomyolysis. Explain what this elevated enzyme level
indicates about the physiology of the muscle cell.
c. Explain why a dusky, dark color in the urine, resulting
from the presence of myoglobin, also indicates muscle
breakdown.
OUTCOMES 9.2, 9.3, 9.4
3. What steps might be taken to minimize atrophy of skeletal
muscles in patients conF
ned to bed for prolonged times?
OUTCOME 9.3
4. As lactic acid and other substances accumulate in an active
muscle, they stimulate pain receptors, and the muscle may
feel sore. How might the application of heat or substances that
dilate blood vessels help relieve such soreness?
ibl
9.9 Life-Span Changes
32
Describe three aging-related changes in the muscular
system. (p. 334)
33
Explain the beneF
ts of exercise for maintaining muscular
health while aging. (p. 334)
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