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Huxley, Hugh (Esmor)

muscle filaments arranged contraction

(1924– ) British physiologist: developed sliding filament theory of muscle contraction.

Huxley studied physics at Cambridge, worked on radar in the Second World War and afterwards was attracted to biophysics, working at the Massachusetts Institute of Technology and in London and in Cambridge from 1961. From the 1950s he was especially associated with the sliding filament model of muscle contraction, with the development of methods in X-ray diffraction and in electron microscopy designed for this work but also applicable in other studies.

Skeletal muscle is a very abundant animal tissue: it makes up some 40% of the human body mass. Its main purpose is to convert chemical energy into mechanical work, under neural control. Skeletal muscle tissue is a parallel array of myofibres, each consisting of some hundreds of myofibrils, which form long cylinders. The myofibril is divided into sarcomeres arranged end to end and, since the myofibrils are arranged with the sarcomeres in register, this gives to skeletal muscle its striated appearance. (The fibres of smooth muscle are not arranged in sarcomeres.) Within each sarcomere are the filaments which form the contractile apparatus; it can shorten by some 10%. These filaments are of two kinds: the thicker myosin filaments interdigitate with the slender actin filaments. With , Huxley developed the theory that these thick and thin protein filaments slide past each other in muscle contraction. The process has a complex system of regulation through changes in calcium ion concentration, and uses ATP as the energy source. When the muscle relaxes the crossbridges which project from the thick filaments and which have drawn the structure together are detached, and the whole structure regains its original length.

Huxley, Thomas Henry [next] [back] Hutton, James

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