Hypogravitational Osteoporosis :: essays research papers

Osteoporosis acondition characterized by an absolute decrease inthe amount of bone present to a level below whichit is capable of haveing the structural integrityof the skeleton. To state the obvious, Humanbeings have evolved under Earths gravity "1G".Our musculoskeleton form have developed tohelp us navigate in this gravitational field, endowedwith ability to adapt as needed under various try on, strains and available energy requirement.The system consists of Bone a highly specializedand dynamic supporting tissue which provides thevertebrates its rigid infrastructure. It consists ofspecialized connective tissue cells calledosteocytes and a matrix consisting of nativefibers held together by an organic cement whichnatural springs bone its tenacity, elasticity and its resilience.It also has an inorganic component located in thecement between the fibers consisting of calciumphosphate 85% Calcium carbonate 10% others 5% which give it the hardness and rigidity.Other than provi ding the rigid infrastructure, itprotects vital organs like the brain, serves as acomplex lever system, acts as a storage area forcalcium which is vital for human metabolism,houses the bone marrow within its mid cavity andto top it all it is capable of changing its architectureand mass in reply to outside and inner stress.It is this dynamic remodeling of bone which is ofprimary interest in microgravity. To feel the impactof this dynamicity it should be noted that a boneremodeling unit a joined phenomena of bonereabsorption and bone formation is initiated andanother finished about every ten seconds in ahealthy adult. This dynamic system responds tomechanical stress or lack of it by increasing thebone mass/density or decreasing it as per thedemand on the system. -eg a person relations withincrease mechanical stress give respond withincreased mass / density of the bone and a personwho leads a sedentary life will have decreasedmass/density of bone but the right amount tosupport his structure against the mechanicalstresses she/she exists in. Hormones also play a major role as seen in postmenopausal femalesosteoporosis (lack of estrogens) in which the rateof bone reformation is usually normal with the rateof bone re-absorption increased. In Skeletalsystem whose mass represent a dynamichomeostasis in 1g weight- bearing,when placed inmicrogravity for any extended period of timerequiring practically no weight bearing, the restrictive system of bone/calcium reacts bydecreasing its mass. After all, why carry all thatextra mass and use all that energy to maintain whatis not needed? Logically the greatest loss-demineralization- occurs in the weight bearingbones of the leg Os Calcis and spine. Bone losshas been estimated by calcium-balance studiesand excretion studies. An increased urinary