PHGY 209 Lecture Notes - Lecture 22: Electrolyte, Lean Body Mass, Adipose Tissue
16 Sep 2016
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Fundamental principle: at all levels of organization, functional activities are directed at maintaining homeostasis, or the relative constancy of the milieu interieur (internal environment: environment surrounding individual cells is vastly different from external environment. Internal environment remains relatively constant under conditions of health. By far, the most abundant single constituent of the body is water. Body water is the medium in which: solutes are dissolved, metabolic reactions take place. If the water content is computed as a fraction of lean body mass (excluding the fat), the differences between individuals become insignificant. Standard values for physiological reference individual: 21 year old, white male, Must make adjustments for: age, gender, weight, ethnic origin. Variations in body water with age and gender: 70 kg male: 42 l water = 42 000 ml. Final concentration in body: 100/42 000 = 0. 0024 mg/ml. 70 kg female: 35 l water = 35 000 ml. Final concentration in body: 100/35 000 = 0. 0029 mg/ml.
