Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

9. Muscle Tissue

Structure of a Skeletal Muscle

Anatomy & Physiology

9. Muscle Tissue

Structure of a Skeletal Muscle

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Problem L3.4

Textbook Question

Mr. Nasheed has cerebral palsy and suffers severe skeletal muscle spasms as a result of his condition. He is prescribed the drug dantrolene, which prevents the release of Ca²⁺ from the SR. Explain how this will treat his muscle spasms.

Verified step by step guidance

Understand the role of calcium ions (Ca²⁺) in muscle contraction: Calcium ions are released from the sarcoplasmic reticulum (SR) in response to a nerve signal. These ions bind to troponin, causing a conformational change that allows actin and myosin filaments to interact, leading to muscle contraction.

Recognize the problem in cerebral palsy: In Mr. Nasheed's case, severe skeletal muscle spasms occur due to excessive or uncontrolled muscle contractions, which are likely caused by overactive release of Ca²⁺ from the SR.

Understand the mechanism of dantrolene: Dantrolene works by inhibiting the release of Ca²⁺ from the SR. This reduces the availability of calcium ions needed for muscle contraction, thereby decreasing the intensity and frequency of muscle spasms.

Connect the drug's action to the treatment of spasms: By preventing excessive Ca²⁺ release, dantrolene helps to relax the muscles and reduce the involuntary contractions that cause spasms.

Summarize the therapeutic effect: The reduction in Ca²⁺ release leads to less activation of the contractile machinery in skeletal muscles, providing relief from the severe spasms associated with cerebral palsy.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cerebral Palsy

Cerebral palsy is a neurological disorder caused by brain damage that affects movement and muscle coordination. Individuals with this condition may experience muscle stiffness, spasms, and difficulty with motor skills. Understanding cerebral palsy is crucial for recognizing the underlying causes of muscle spasms in patients like Mr. Nasheed.

Calcium Release in Muscle Contraction

Muscle contraction is initiated by the release of calcium ions (Ca2+) from the sarcoplasmic reticulum (SR) into the muscle fibers. This calcium release triggers the interaction between actin and myosin, leading to muscle contraction. In conditions like cerebral palsy, excessive calcium release can lead to uncontrolled muscle spasms, making it essential to understand this process for effective treatment.

Dantrolene Mechanism of Action

Dantrolene is a muscle relaxant that works by inhibiting the release of calcium from the sarcoplasmic reticulum in muscle cells. By reducing calcium availability, dantrolene decreases the strength and frequency of muscle contractions, thereby alleviating muscle spasms. This mechanism is particularly beneficial for patients with conditions that cause excessive muscle activity, such as cerebral palsy.

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Textbook Question

The function of the T tubules in muscle contraction is to:

a. Make and store glycogen

b. Release Ca²⁺ into the cell interior and then pick it up again

c. Transmit the action potential deep into the muscle cells

d. Form proteins

True or false: Most muscles contain a predominance of one skeletal muscle fiber type. Explain the reasoning behind your choice.

The primary action of the biceps brachii muscle of the anterior arm is to flex the forearm at the elbow. However, when this muscle is inflamed, pain is felt in the shoulder. Explain this finding.

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Textbook Question

Which of the following types of muscle fibers have low myosin ATPase activity and are classified as slow-twitch?

a. Type I fibers

b. Type IIa fibers

c. Type IIx fibers

d. Type III fibers

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Textbook Question

Michael had a nervous habit of chewing on the inner lining of his lip with his front teeth. The lip grew thicker and thicker from years of continual irritation. Michael's dentist noticed his greatly thickened lip, then told him to have it checked to see if the thickening was a tumor. A biopsy revealed hyperplasia, but no evidence of neoplasia. What do these terms mean? Did Michael have cancer of the mouth?

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Why are the connective tissue wrappings of skeletal muscles important? Name these connective tissue coverings, beginning with the finest and ending with the coarsest.

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Textbook Question

Why are the connective tissue wrappings of skeletal muscles important? Name these connective tissue coverings, beginning with the finest and ending with the coarsest.

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Textbook Question

Compartment syndrome can result from all of the following except

(a) Compressing a nerve in the wrist

(b) Compartments swelling with blood due to an injury involving blood vessels

(d) Pulled tendons in the muscles of a given compartment

(e) Torn muscles in a particular compartment

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