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A scanner used to measure bone density using dual energy X-ray absorptiometry. Bone density, or bone mineral density, is the amount of bone mineral in bone tissue.The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. [1]
Nevertheless, one object will always weigh more than another with less mass if both are subject to the same gravity (i.e. the same gravitational field strength). In scientific contexts, mass is the amount of "matter" in an object (though "matter" may be difficult to define), but weight is the force exerted on an object's matter by gravity. [1]
On Mars, where gravity is about one-third that of earth, the gravitational forces acting on astronauts' bodies would be much lower, causing bones to decrease in mass and density. [ 6 ] Average bone loss of 1–2% was recorded in astronauts on Mir each month. [ 2 ]
A wide variety of body composition measurement methods exist. The gold standard measurement technique for the 4-compartment model consists of a weight measurement, body density measurement using hydrostatic weighing or air displacement plethysmography, total body water calculation using isotope dilution analysis, and mineral content measurement by dual-energy X-ray absorptiometry (DEXA). [1]
In physics, gravity (from Latin gravitas 'weight' [1]) is a fundamental interaction primarily observed as mutual attraction between all things that have mass.Gravity is, by far, the weakest of the four fundamental interactions, approximately 10 38 times weaker than the strong interaction, 10 36 times weaker than the electromagnetic force and 10 29 times weaker than the weak interaction.
The bone mass in the skeleton makes up about 14% of the total body weight (ca. 10–11 kg for an average person) and reaches maximum mass between the ages of 25 and 30. [2] The human skeleton can be divided into the axial skeleton and the appendicular skeleton .
It is still unknown whether bone recovers completely. Unlike people with osteoporosis, astronauts eventually regain their bone density. [citation needed] After a 3–4 month trip into space, it takes about 2–3 years to regain lost bone density. [citation needed] New techniques are being developed to help astronauts recover faster. Research on ...
Peak bone mass is typically lower in females than males, and is also lower in White people and Asians compared to black populations. [1] A way to determine bone mass is to look at the size and density of the mineralized tissue in the periosteal envelope and using the bone mineral density (BMD) of a person can help determine the strength of that ...