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A Thick Filament is one of the two types of protein filaments
that, together form cylindrical structures call myofibrils and
which extend along the length of muscle fibres.
(The other type of protein
filament that is found in myofibrils is called a thin
filament.)
Thick filaments are formed from a proteins called
myosin
grouped in bundles as shown below.
Above:
Labelled diagram of a Thick Filament.
The myosin molecules are arranged in a bipolar structure within
thick filaments - their protruding club-like heads pointing
towards the ends and their shafts towards the middle. Therefore each thick
filament has a central, bare, zone and an array of protruding
heads of opposite polarity at each end.
Thick filaments are typically 130 nm long
and 12 to 15 nm in diameter.
(There are 1,000,000,000 nm in a metre, or
1,000,000 nm in one mm.)
They self-assemble in vitro under the
right ionic conditions.
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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