Your Bones in Space

Essay by Rusty1High School, 11th gradeA+, November 1996

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Hypogravitational Osteoporosis: A review of literature.

By Lambert Titus Parker. May 19 1987. (GEnie Spaceport)

Osteoporosis: a condition characterized by an absolute decrease in the

amount of bone present to a level below which it is capable of maintaining

the structural integrity of the skeleton.

To state the obvious, Human beings have evolved under Earth's gravity

'1G'. Our musculoskeleton system have developed to help us navigate in

this gravitational field, endowed with ability to adapt as needed under

various stress, strains and available energy requirement. The system

consists of Bone a highly specialized and dynamic supporting tissue which

provides the vertebrates its rigid infrastructure. It consists of specialized

connective tissue cells called osteocytes and a matrix consisting of

organic fibers held together by an organic cement which gives bone its

tenacity, elasticity and its resilience. It also has an inorganic component

located in the cement between the fibers consisting of calcium phosphate

[85%]; Calcium carbonate [10%] ; others [5%] which give it the hardness

and rigidity.

Other than providing the rigid infrastructure, it protects

vital organs like the brain], serves as a complex lever system, acts as a

storage area for calcium which is vital for human metabolism, houses the

bone marrow within its mid cavity and to top it all it is capable of changing

its architecture and mass in response to outside and inner stress. It

is this dynamic remodeling of bone which is of primary interest in microgravity.

To feel the impact of this dynamicity it should be noted that a bone

remodeling unit [a coupled phenomena of bone reabsorption and bone formation]

is initiated and another finished about every ten seconds in a healthy

adult. This dynamic system responds to mechanical stress or...