Total body bone mass

Compston, J. E., Laskey, M. A., Croucher, P. 1., Coxon, A., and Kreitzman, S. (1992). Effect of diet-induced weight loss on total body bone mass. Clin. Sci. (Land.) 82, 429 32. 

Poorly perfused tissues (adipose tissue, connective tissue, and bone) require hours to come into equilibrium with plasma drug concentrations (Fig. 25.1). Since the accumulation of anesthetic in body fat is relatively small soon after its IV administration, it is common clinical practice to calculate drug dosage on the basis of lean body mass rather than on total body weight. Thus, an obese patient may receive the same dose of IV anesthetic as a patient of normal body weight. 

Two imaging systems, dual energy X-ray absorptiometry scanning (DEXA) and magnetic resonance imaging (MRI), allow for longitudinal studies of whole body composition. DEXA measures bone mineral density and content, fat content, and lean content in anesthetized mice. Echo MRI from Echo Medical System, Houston, TX, is used to measure whole body composition parameters such as total body fat, lean mass, body fluids, and total body water in live mice without the need for anesthesia or sedation (15). The MRI technology is more rapid, less than a minute to scan one mouse, than DEXA which takes about 5 min per mouse. 

The distribution of uranium in the human body, based on the mean concentrations in Table 4, the mean bone concentration given above, and the ICRP Reference Man tissue and blood weights, is depicted in Fig. 1. Clearly the skeleton is the primary repository of uranium in humans, but because of the large masses of fat and muscle, these tissues may approach the quantity in bone. Confirmatory measurements of uranium in muscle and fat should be made since the estimates are based on only one and two reports, respectively. The total body content based on global estimates of these soft tissues, blood, and bone is 55 p.g of uranium (680 mBq). The ICRP estimated the uranium content of Reference Man to be 90 p.g (1100 mBq) [27]. The primary difference in these estimates is the evaluation of the skeletal content. 

Body composition is a more sensitive indicator of infant nutritional status than measures of size. Depending on the method used, measurements can provide the mass of lean tissue, fat tissue, total body water, and bone. Methods vary greatly in terms of invasiveness, feasibility, cost, technology, need for trained personnel, accuracy, reliability, and precision. The most feasible methods for assessing infant body composition include anthropometry (e.g., skinfold measurements), dual X-ray absorptiometry (DEXA), and isotope dilution. A recent review concluded that for intergroup comparisons, skinfold thicknesses were useful, but for individual infant assessments, DEXA was recommended (Koo, 2000). In the absence of reference data based on a large sample of infants, the interpretation of body... 

Collagen, a class of fibrous protein, is the most abundant protein in the human body, accounting for approximately 25% of the total protein mass. It is the main component of the ECM and serves as a stmctural protein in connective tissues, such as skin, bone, cartilage, and blood vessels. Twenty-eight types of collagen have been identified in humans to date (Kar et al. 2006). Among these, collagen types I-III are the most abundant. 

There are three types of muscles smooth, cardiac, and skeletal. Smooth muscles help move food and fluids through your body. Cardiac muscles pump blood through your heart. Skeletal muscles are the kind that attach to your bones. They allow you to run, dance, lift, turn, and, in general, move through your environment. Physical fitness involves resilience in all muscle types. For this essay, however, our focus will be on the more physically apparent skeletal muscles, which can account for up to 40 percent of your total mass. 

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