The Cardiovascular System in Space

Abstract

In space the human body and, in particular, the cardiovascular system are exposed to an altered and unfamiliar environment. The new set of stimuli imposes novel challenges on the cardiovascular system. More precisely, a lack of the impeding gravitational force makes some cardiovascular functions more facile. Upon injection to space, extensive mechanisms that have been evolutionarily developed to cope with the burden of gravity become redundant. Next to the skeletal and muscular system, the cardiovascular system is less strained in weightlessness than on Earth and is deconditioned during longer periods spent in space. As far as current experience has shown, this process continues throughout the stay in microgravity and poses severe challenges to astronauts returning to Earth. One must understand the timeframe and severity of all areas of cardiovascular deconditioning in order to evaluate the feasibility of manned missions and ensuring a safe return to a gravitational field—be it Earth, Mars, or another planet. This chapter outlines our current knowledge of cardiovascular deconditioning in microgravity, hypothesized through terrestrial simulations and partly validated by experiments in space.