BOX 2–1 Some Major Human Physiological Changes Resulting from Extended Travel in Earth Orbit
Loss of bone mineral density
Loss of skeletal muscle
Loss of hydrostatic pressure
Changes in pulmonary circulation and gas exchange
Decrease in absorption or malabsorption
Disturbed fine motor and gross motor functions
Altered sleep-circadian rhythm and sleep deprivation
Effects of radiation on gametes
Hematological and Immunological Systems
Potential immunologic depression
Source: Billica, 2000.
are by no means exhaustive, however. The material in this chapter is arranged by organ system, with those for which the physiological effects are best documented presented first. The chapter also includes a discussion of future methods for the monitoring of astronauts’ health status—an important aspect of detecting, understanding, and countering the untoward physiological changes that may affect astronaut well-being and mission performance.