A sarcomere is the basic
functional within muscle cells. This unit is distinctive in muscle
tissue is observed on microscope slides due to the striated nature
of both skeletal and cardiac muscle. (Smooth muscle has
a similar contractile mechanism but is not so highly organized and does
not show striations).
Striations are caused by alignment of bands. The most prominent striations
are due to the
A
bands, the I
bands, and the lines of Z
discs.
The unit between two Z lines is called a sarcomere. In the A band the proteins actin and myosin are both present whereas
the I band contains only actin.
Above:
Diagram of the unit within a muscle cell that is known as a sarcomere.
When muscle contracts the sarcomere shortens and the lines
of the Z
discs move closer together.
An interesting article about: Measuring Sarcomere
Length Using Laser Diffraction
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. |
