Effects Of Microgravity On Human Circulatory System

With exercise, an athlete will strengthen his heart muscle and make it more efficient; any reduction in demand will lessen this efficiency. Similarly immersion in water of the weightlessness of space flight causes a progressive l

Researchers have conducted most previous circulatory studies pre and post flight, but it has been difficult to separate the direct effects (e.g. increase in blood pressure, decrease in heart muscle mass, sudden drop in blood pressure, etc.) of weightlessness from the indirect effects resulting from the stress of post flight recovery. John T. Shepherd, Director of Research at the Mayo Clinic, Rochester, Minn., reported at the Skylab Medical Experiments Symposium: “The wealth of data which has been accumulated on the adjustments of man to space travel . . . truly establish his future role in the exploration of the universe.”

The National Research Council has reported that two-thirds of Americans returning from space shuttle missions and tested after their flights showed an impaired ability to maintain adequate blood pressure. Such effects, if they get worse, could make such maneuvers as docking with space stations and landing on other planets more hazardous to the crews. Joe Kerwin, a doctor of medicine, and a commander in the Naval Medical Corps, stated: “It was a continuous and pleasant surprise to me to find out how easy it was to live in zero g, and how good we felt.” Still, these changes in the circulatory system must be understood and controlled because they could have undesirable consequences on longer missions in space (Belew 144)

can fully adapt to a weightless environment, perform in an efficient and effective

Weightlessness causes in effect an alteration of the heart’s functions. The cardiopulmonary system – which controls ventilation, blow flow, gas exchanges, and pressure of air in the lungs – is affected. The body fluids shift to the upper body, with blood tending to pool in the chest, neck, and head. This then causes a feeling of fullness in the head, study sinuses, and puffy eyes. Effecting the legs that shrink, another problem associated with fluid shift is the resulting diuretic effect, leading to reduction of blood volume, as well as frequency of urination and possible dehydration. Without gravity, the heart begins to relax, adjusting to its lower work load by slowing down and shrinking (Carreau 11).

Space travelers certainly feel gravitationally challenged during and just after their descent. Returning space travelers report experiencing a variety of illusions – for example, during head moti

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