AbstractData have been accumulated from a series of studies in which men have been subjected to weightlessness in orbital space flight for periods of up to 12 weeks. These data are used to predict the long term consequences of weightlessness upon the skeletal system. Space flight induced a loss of calcium which accelerated exponentially from about 50 mg/d at the end of 1 week to approx. 300 mg/d at the end of 12 weeks. The hypercalciuria reached a constant level within 4 weeks while fecal calcium losses continued to increase throughout the period of exposure. This apparent diminution of gastrointestinal absorptive efficiency was accompanied by a slight decline in the plasma level of parathyroid hormone and a slight elevation in the plasma level of calcium and phosphorus. Although losses in mineral from the calcaneus were closely correlated with the calcium imbalance, no changes were detected in the mineral mass of the ulna and radius. From the data presented it is concluded that the process of demineralization observed in space flight is more severe than would be predicted on the basis of observations in immobilized, bed rested, or paralyzed subjects. It is, moreover, suggested that the process may not be totally reversible.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Prolonged weightlessness and calcium loss in man


    Contributors:

    Published in:

    Acta Astronautica ; 6 , 9 ; 1113-1122


    Publication date :

    1979-01-01


    Size :

    10 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



    Prolonged weightlessness and calcium loss in man

    Rambaut, P. C. / Johnston, R. S. | NTRS | 1979


    Orientation in prolonged weightlessness (ISS HRF-E085)

    Smith, Laurence / Smith, Theodore / Howard, Ian et al. | AIAA | 2001



    Prolonged weightlessness, reference frames and visual symmetry detection

    Leone, G. / De Schonen, S. / Lipshits, M. et al. | British Library Conference Proceedings | 1998


    Effects of prolonged weightlessness on a human otolith-spinal reflex

    Watt, D. G. D. / Money, K. E. / Tomi, L. M. | NTRS | 1983