Composition of the human body not in an essential biological role. The average adult human body contains approximately atoms and contains at least detectable traces of 60 chemical elements. About 29 of these elements are thought to play an active positive role in life and health in humans. The relative amounts of each element vary by individual, mainly due to differences in the proportion of fat, muscle and bone in their body. Persons with more fat will have a higher proportion of carbon and a lower proportion of most other elements (the proportion of hydrogen will be about the same). The numbers in the table
Effect of spaceflight on the human body adult. In space, however, there is an increase in osteoclast activity due to microgravity. This is a problem, because osteoclasts break down the bones into minerals that are reabsorbed by the body. Osteoblasts are not consecutively active with the osteoclasts, causing the bone to be constantly diminished with no recovery. This increase in osteoclasts activity has been seen particularly in the pelvic region, because this is the region which carries the biggest load with gravity present. A study demonstrated that in healthy mice, osteoclasts appearance increased by 197%, accompanied by a down-regulation of osteoblasts and growth factors that are known