QUANTIATIVE DECISION MAKING ASSIGNMENT

Quantiative Decision Making Assignment

Quantiative Decision Making Assignment

It is possible to distinguish macroscopically two types of skeletal striated muscle in vertebrates based on their colour: the lighter the muscle is contracting faster and darker contracting more slowly. This observation defines two major classes of muscles: the muscles composed of fibres called slowly (type I fibres: cf. below) and fast (type II fibres). In humans, unlike other species, anatomical separation of different types of fibres is not clearly defined, and while some muscles are more likely to fast or slow, several fibre types coexist within the same muscle. Slow fibres are characterized macroscopically fast fibres by their smaller diameter as well as their oxidative capacity increased, resulting in a greater number of mitochondria.

Historically, a large number of classifications, based on the muscle contractile protein content or metabolism have been proposed to account for the heterogeneity of structural and functional muscle, but only a small number of them have been widely applied. (Dahmane, 2005, 2451)

Two Furthermore, there is no currently unable to satisfactorily account for the complexity of muscle tissue and it is not possible to consistently correlate the different methodologies used. The multiplicity of classification systems and the partial overlap of words forming their nomenclature greatly complicate the analysis of literature data and make it necessary to take into account the methodology used in order to draw valid conclusions.

Contractile proteins

To date, the most common methods for delineation of muscle fibre types are based on identifying specific patterns of myosin isoforms and particularly myosin heavy chains.

A widely used technique is to measure the ATPase activity of muscle fibres on histological sections by analyzing the intensity of staining of single fibres by precipitation, dependent ATPase, a pigmented compound. In this way, it is possible to show an inverse relationship between speed of contraction and ATPase activity, slow fibres are the most active. The sensitivity at pH 4.5 and at 6 of formaldehyde ATPase activity has subdivided the original classification into several sub-types of fibres, three main areas: I, IIA and IIB as well as several intermediate: IC, IIC, IIAC, and IIAB. It should be noted however that this method based on the overall enzyme activity of fibres analyzed cannot pronounce accurately on its content of specific contractile proteins.

Electrophoresis of muscle extracts to separate the different isoforms of muscle proteins according to their size. The site of the ATPase activity located on the globular portion of myosin heavy chain, the link between ATPase activity and MyHC isoforms isolated by electrophoresis led by analogy to nomenclature, the definition of MyHC isoforms Ib / s (b in the heart muscle, the muscle s in slow) and MyHC IIa and IIb and later MyHC IId / x (isolated independently in different species, hence the nomenclature loaded), which are the major isoforms of adult skeletal muscle. Intermediate fibre types, defined by ATPase activity, consistent with fibres expressing mixtures of these isoforms, it should be noted however that there is variability among species and in humans; ...