General Introduction

Abstract

Microgravity is an extreme environment Astronauts are exposed to when they escape Earth’s gravitational field. A different set of stimuli experienced during spaceflight seriously affects all parts of the body. Instantly, the body starts to adapt to the new gravity-free environment; different organs and organ systems do so in different ways and at different rates. The cardiovascular system, for example, no longer needs to work against gravity and extensive mechanisms that maintain cerebral perfusion and prevent lower body edema on Earth become redundant and weaken. As reasonable as those adaptations might be in Space, they become critical upon return to Earth’s gravitational field. Therefore, it is important to grant the changes in the cardiovascular system special attention. This chapter briefly outlines physiological functions that are critical for understanding the changes occurring in microgravity, as well as introducing the microgravity environment aboard Space stations.