What about their bones?

     As a Registered Nurse that is certified in Orthopedics I found Chapter Eleven, "The Horizontal Stuff.  What if you never got out of bed?"  the most interesting.  I work with bones all day on a total joint and spine unit.  We take care of the patients after their surgeries until they are ready to go home.  The health of the astronauts bones never crossed my mind until reading this book.  Bones are a prime example of if you don't use it you lose it.  "Astronauts returning from six month space station stint with 15 to 20 percent less bone than they had when they left" (Roach, 219).
     There is a threat of breaking bones when you return to Earth and step out of the space shuttle.  The astronauts are able to rebuild their bone over time by stressing it.  The osteoclasts break down the weak bone and then the osteoblasts built new, stronger bone.  It is very interesting that NASA pays $17,000 for people to maintain bed rest for three months.  It is a good way to judge how much bone and muscle wasting happens while the astronaut is in space not bearing weight or stressing their muscle and bone.
     Being an astronaut is not only mentally stressful but it also causes some serious changes to their physical body.  The astronaut can regain their muscle and bone but it is a long process that can be painful. Not to mention that they may break a bone and the recovery from that may involve surgery and months of rehabilitation.  Being an astronaut must be an amazing job to make a person put their mental and physical health on the line.