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How the Body Adapts to Space
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20368 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
6 / 1992 |
2,856 Words |
| Author
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Marsha Freeman
Marsha Freeman, of Leesburg, Virginia, is associate editor of
21st Century Science & Technology magazine. |
When a human being goes into space, the body quickly begins to adapt to the gravity-free environment: The fluids in the body shift, the bones start to lose calcium, the heart and circulatory system decondition, and a felling of queasiness and disorientation comes on in this world without up or down. Interestingly enough, many of these physiological changes that occur in healthy spacefarers mimic the symptoms of many debilitating diseases on earth.
This observation has given doctors and scientists a twofold mission as they attempt to expand the knowledge of human biology through space research. The primary goal is to understand the changes that take place during space flight to ensure that astronauts remain healthy and productive during the mission and also on their return to earth.
The secondary goal derives from the promise that what is learned in space will shed light on the mechanisms that incapacitate tens of millions of people with osteoporosis, heart and lung disease, immune diseases, and other chronic disabilities. Recent space shuttle flights, experiments on future shuttle missions, and research aboard the space station will shed light on how the human body functions when it is adapting to space and when it becomes ill on earth.
The body in weightlessness
The first change due to weightlessness observable to mission control is that the faces of the crew members appear puffy. The astronaut generally feels a stuffiness, similar to nasal or sinus, congestion on earth. This is because in space, the body fluids shift to more evenly distribute themselves, whereas on earth blood pools in the lower extremities due to gravity. Because there is now more fluid in the upper portion of the torso and head, the body senses that there is too much total fluid in the system and begins to eliminate the excess as urine.
Besides the increased production of urine to eliminate fluid, there is also a decrease in the number of circulating red blood cells, a condition described as "space anemia." In addition, the heart has to perform less work to circulate the blood and maintain adequate blood pressure because of the lack of gravity. The shrinkage of heart muscle is similar to the deconditioning of other muscles in the body that takes place in space.
A majority of space travelers would doubtless agree that the most uncomfortable effect of adjusting to
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