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The H Zone is a term used to refer to an area within
a sarcomere.
A sarcomere is the repeating functional unit of "striped"
or "striated" muscle.
"Striated muscle" is also known as "skeletal
muscle", "voluntary muscle", and "cardiac muscle". Its striated (stripey)
visual appearance is
due to alternating (dark) A
bands and (light) I
bands. The relative
sizes of the H Zone,
the A
band, and the I
band of sarcomeres are determind by, and provide information about,
the state of contraction or relaxation of the muscle tissue of which
the sacromere is a part.
This is illustrated below:
Above:
Diagram of the unit within a muscle cell that is known as a sarcomere.
The H
Zone is at the centre of the A band of each sarcomere.
This is the region in which there are only thick filaments,
and no thin filaments.
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. |
