KINESIOL 3U03 Lecture Notes - Lecture 3: Skeletal Muscle, Myocyte, Myogenesis
16 Feb 2016
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Document Summary
Spread apart - separated by extracellular material in between the fibres. More closely packed less extracellular material. Over time - alterations in chemical composition of the muscle fibre, and the muscle itself. With growth: some electrollytes decr in content, water changes, etc, reduction in concentration of extracellular ions (na and cl, increase in concentration of intracellular components (k and p, water % decreases, extracellular component decreases. After birth an increase in muscle = increase in muscle size of the fibre (some incr in # till about 1 year) Total muscle nitrogen increases (nonprotein and cellular: prenatal to adulthood. Extracellular protein % increases to maximum amount at birth: slowly declines postnatally to adulthood, b/c extracellular component gets less b/c muscle more tightly packed, parallels increase fibre number prenatal increase fibre size postnatal. Implications in body composition assessment: these changes present challenges in body comp measurements across, bioelectrical impedance w/pediatric equations accommodate for the lifespan changes in concentration.
