318
UNIT 2
Covering, Support, and Movement of the Body
2.
When a suicide victim was found, the coroner was unable to
remove the drug vial clutched in his hand. Explain the reasons for
this. If the victim had been discovered three days later, would the
coroner have had the same difficulty? Explain.
3.
Muscle-relaxing drugs are administered to a patient during major
surgery. Which of the two chemicals described next would be a
good skeletal muscle relaxant and why?
Chemical A binds to and blocks ACh receptors of muscle cells.
Chemical B floods the muscle cells’ cytoplasm with Ca
2
1
.
4.
Michael is answering a series of questions dealing with skeletal
muscle cell excitation and contraction. In response to “What
protein changes shape when Ca
2
1
binds to it?” he writes
“tropomyosin.” What should he have responded and what is the
result of that calcium ion binding?
25.
Define EPOC.
26.
Smooth muscle has some unique properties, such as low energy
usage, and the ability to maintain contraction over long periods. Tie
these properties to the function of smooth muscle in the body.
Critical Thinking
and Clinical Application
Questions
1.
Jim Fitch decided that his physique le± much to be desired, so he
joined a local health club and began to “pump iron” three times
weekly. A±er three months of training, during which he li±ed
increasingly heavier weights, he noticed that his arm and chest
muscles were substantially larger. Explain the structural and
functional basis of these changes.
Related Clinical Terms
Fibromyositis
(
fibro
5
fiber;
itis
5
inflammation) Also known
as
fibromyalgia
; a group of conditions involving chronic
inflammation of a muscle, its connective tissue coverings and
tendons, and capsules of nearby joints. Symptoms are nonspecific
and involve varying degrees of tenderness associated with specific
trigger points, as well as fatigue and frequent awakening from sleep.
Hernia
Protrusion of an organ through its body cavity wall. May
be congenital (owing to failure of muscle fusion during
development), but most o±en is caused by heavy li±ing or
obesity and subsequent muscle weakening.
Myalgia
(mi-al
9
je-ah;
algia
5
pain) Muscle pain resulting from any
muscle disorder.
Myofascial pain syndrome
Pain caused by a tightened band of
muscle fibers, which twitch when the skin over them is touched.
Mostly associated with overused or strained postural muscles.
Myopathy
(mi-op
9
ah-the;
path
5
disease, suffering) Any disease of
muscle.
Myotonic dystrophy
A form of muscular dystrophy that is less
common than DMD; in the U.S. it affects about 14 of 100,000
people. Symptoms include a gradual reduction in muscle mass
and control of the skeletal muscles, abnormal heart rhythm,
and diabetes mellitus. May appear at any time; not sex-linked.
Underlying genetic defect is multiple repeats of a particular gene
on chromosome 19. Because the number of repeats tends to
increase from generation to generation, subsequent generations
develop more severe symptoms. No effective treatment.
RICE
Acronym for rest, ice, compression, and elevation. ²e
standard treatment for a pulled muscle, or excessively stretched
tendons or ligaments.
Spasm
A sudden, involuntary twitch in smooth or skeletal muscle
ranging from merely irritating to very painful; may be due to
chemical imbalances. In spasms of the eyelid or facial muscles,
called tics, psychological factors may be involved. Stretching and
massaging the affected area may help end the spasm. A cramp is
a prolonged spasm; usually occurs at night or a±er exercise.
Strain
Commonly called a “pulled muscle,” a strain is excessive
stretching and possible tearing of a muscle due to muscle
overuse or abuse. ²e injured muscle becomes painfully
inflamed (myositis), and adjacent joints are usually immobilized.
Tetanus
(1) A state of sustained contraction of a muscle that
is a normal aspect of skeletal muscle functioning. (2) An
acute infectious disease caused by the anaerobic bacterium
Clostridium tetani
and resulting in persistent painful spasms of
some skeletal muscles. Progresses to fixed rigidity of the jaws
(lockjaw) and spasms of trunk and limb muscles. Usually fatal
due to respiratory failure.
AT T H E C L I N I C
9
Let’s continue our tale of Mrs.
DeStephano’s medical problems,
this time looking at the notes made
detailing observations of her skeletal
musculature.
Severe lacerations of the muscles of the right leg and knee
Damage to the blood vessels serving the right leg and knee
Transection of the sciatic nerve (the large nerve serving most of
the lower limb), just above the right knee
Her physician orders daily passive range-of-motion (ROM) exercise
and electrical stimulation for her right leg and a diet high in
protein, carbohydrates, and vitamin C.
1.
Describe the step-by-step process of wound healing that
will occur in her fleshy (muscle) wounds, and note the
consequences of the specific restorative process that occurs.
2.
What complications in healing can be anticipated owing to
vascular (blood vessel) damage in the right leg?
3.
What complications in muscle structure and function result
from transection of the sciatic nerve? Why are passive ROM
and electrical stimulation of her right leg muscles ordered?
4.
Explain the reasoning behind the dietary recommendations.
(Answers in Appendix H)
Case Study
Muscular System
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