Practice no. 12 – Muscle tissue (deadline 8. 5. 2020)
1. Characterize and graphically schematize ultrastructure of a muscle fiber (rhabdomyocyte).
Draw into the scheme: nuclei, sarcolemma, myofibrils, t-tubuli, sER, mitochondria.
Indicate where a triad is located.
2. Graphically schematize structure of the sarcomere as it appears in the TEM. Into the
scheme position: actin and myosin myofilaments and other proteins (-actinin, titin,
nebulin). Determine which parts of the sarcomere change their size during contraction.
Estimate the size of sarcomere (in m) and extent of contraction (in %).
3. Schematically describe mechanism of muscle contraction. Determine the mechanism of
action and position it into the scheme of contraction: botulotoxin, kurare and myasthenia
gravis disorder.
4. How are the biomechanical forces transmitted to surrounding connective tissue, tendons
and ligaments? What is the role of protein dystrophin? What is the dystrophin-associated
pathology?
5. How is the connective tissue arranged in muscles? Graphically schematize endomysium,
perimysium and epimysium.
6. What are the principal differences between cardiac and skeletal muscle tissue? Is there
any difference in structure of myofibrils and sarcomere?
7. What is the structure and function of intercalated discs?
8. Graphically schematize the structure of the leiomyocyte. How is the cytoskeleton in
leiomyocyte organized to perform contraction? How the contraction is regulated?
9. What is the embryonic origin of skeletal, cardiac and smooth muscle tissues?
10. Describe the “myoblast”, “myotube” and “(myo)satellite cells” and position them
correctly into the muscle development scheme.
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