Download The Muscular System Clinical Applications and Diagrams, Chapter 8

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The Muscular System
Clinical Applications and Diagrams, Chapter 8
Part I. Clinical Applications
1. Chris, who works at a pesticide factory, comes to the clinic complaining of muscle spasms that
interfere with his movement and breathing. A blood test shows that he has been contaminated
with organophosphate pesticide, which is an acetylcholinesterase inhibitor. How would you
explain to Chris what this means.
The pesticide is a chemical that inhibits the enzyme that destroys acetycholine. Acetycholine
remains in the synapse and continually stimulates muscle activity - spasms
2. You return home to find your little sister crying about her dead hamster Sparky, who is very
stiff. In an effort to cheer your sister up you decide to teach her about why Sparky is so stiff.
What are the details of this condition that causes the stiffness.
The condition is known as rigor mortis and usually occurs several hours after death. It is
caused by a lack of ATP in muscles to allow cross-bridges to release. Upon death, muscle
cells are unable to prevent calcium entry. This allows myosin to bind to actin. Since there is
no ATP made postmortem, the myosin cannot unbind and the body remains in a state of
muscular rigidity for a day or two.
3. A friend of yours returns from the doctor and says that they were diagnosed with Myasthenia
Gravis. She isn’t sure what the condition is and asks you, a brilliant young anatomist, to
explain it to her.
Myasthenia gravis is an autoimmune disease where antibodies attack the ACh receptors on
the neuromuscular junctions. It results in progressive weakening of the skeletal muscles.
Treatment usually involves anticholinesterases such as neostigmine or physostigmine.
These decrease the activity of acteylcholinesterase and help to restore muscle strength.
4. Your grandmother wants to get rid of her facial wrinkles by using BOTOX. She doesn’t
understand what it is and why it works. Give an explanation for the details about BOTOX.
BOTOX is a trade name that stands for botulinum toxin, which is produced by the bacterium
Clostridium botulinum. The Toxin inhibits acetylcholine release by motor neurons at the
neuromuscular junctions resulting in muscle paralysis. Paralyzed muscles do not contract to
wrinkle the skin and thus help to eliminate wrinkles – as well as certain facial expressions.
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Part II
1. Perimysium
2. epimysium
3. sarcomere
4. myofiber
5. endomysium
6. sarcolemma
7. myofibril
8. myofilament
9. tendon
10. fascicle
11. tendon
Part III
1. Motor unit
2. axon terminals
3. synaptic cleft
4. acetylcholine
Part IV
1. 1
2. 4
3. 7
4. 2
5. 5
6. 3
7. 6
8. contraction
9. epimysium
10. fascicles
11. tendon
12. sarcolemma
13. T tubules
14. sarcomeres
15. cross-bridges
16. action potentials
17. troponin
18. motor unit
19. ATP
20. smooth muscle
21. sphincter muscles
12. epimysium
13. endomysium
14. myofiber
15. myofibril
16. perimysium
17. fascicle
18. epimysium
19. perimysium
20. endomysium
21. tendon
22. mitochondrion
23. transverse tubule
24. sardoplasmic
reticulum
25. nucleus
26. myofibril
27. sarcolemma
28. sarcomere
29. thin filament
30. thick filament
31. I band
32. A bind
33. Z disc (line)
5. nerve impulse (action
potential)
6. depolarization
7. T tubule
8. synaptic vesicles
9. acetylcholine
receptors
10. mitochondrion
11. synaptic cleft
12. sarcomere