Learn about the importance of studying the effects of weightlessness on the human body.
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The Effects of Weightlessness on the Human Body At the beginning of man’s entry into space, it was uncertain how we would react to space flights. We also did not know if we could survive the weightlessness or even if we could work in space. The human body is a very complex piece of machinery, which relies on civil subsystems that perform its functions. The human body is affected to some degree by space flights. The most dramatic change occurs immediately after we become weightless. On earth, gravity pulls our body fluids towards our feet, legs, and abdomen. However, when we enter space, the fluid in our body is no longer pulled down towards our feet, but shifts up-to our chest and head. And that changes the way we look. Our faces get puffy and our legs become skinny. After some time, the astronauts adapts somewhat to these fluid shifts. However, their bodies remained in this salted state until they’re back on earth. It does not affect the everyday activities that an astronaut must achieve. One of the tasks of the space shuttle missions was to study the human heart and the way it functions in space. The human cardiovascular system works well in gravity, no matter whether we’re standing or lying. We always have sufficient blood supply to the brain and other vital organs. But we’re going to space and take our hearts out of the normal environment, some strange things happen. The upward shift of fluid in the body tricks the heart and it senses into believing that there’s an increase blood supply. So the heart tries to compensate. First, the muscle structure of the heart compensates by stretching so that the heart can hold more blood. When this happens, the body systems tell the kidneys to eliminate what appears to be excess fluid. When the astronaut returns to earth from space, gravity pulls much of the blood back to the legs. Now there’s not enough blood to go around, and in some people, there was a feeling of light-headedness until the body manufactures more blood. Before departing earth, astronaut Drew Gaffney had a catheter inserted into his heart through a vein in his arm. During the first few hours of flight, when the fluid shifts occur, they were able to measure the central venous pressure need through his heart. The experiment showed that he experienced the much more rapid fall in central venous blood pressure then was predicted. For earth bound people, this experiment may help fight disease.

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