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T Tubules (a term abbreviated from the their full name
Transverse
Tubules) are tunnel-like extensions of sarcolemma that
pass through muscle fibers from one side to the other.
It is due to the side-to-side (across the muscle) orientation of these
structures that they are referred to as "transverse".
T tubules play an important role in the physiology of
muscle contraction:
- Muscle action potential (that is, movement
of electrical charge) travelling along T tubules trigger the release
of calcium(2+) ions from the sarcoplasmic
reticulum.
- This allows the calcium (2+) ions to flood into the sarcoplasm,
- which causes actions and movements of proteins (including actin, myosin,
troponin, and tropomyosin) within the myofibrils that
eventually muscle contraction.
This Section consists of short summaries about the
structures that form the muscles of the body.
This list is not exhaustive but is intended to be appropriate for students
of A-Level Human Biology, ITEC courses in massage and related subjects,
and some other courses in Health Sciences.
For more general information about Muscles see
the pages about: Anterior
Muscles, Posterior
Muscles, Facial
Muscles, Terminology
about Muscles, and the Structure
of Muscles.
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