The present invention relates to apparatuses and methods for measuring three important physiological systems, circulation, breathing, and body water compartments. More specifically, the present invention relates to apparatuses and methods for a continuous simultaneous/synchronized and noninvasive measurement of heart pump function, elastic properties of the vascular system, systemic vascular resistance, breathing capacity, and body water compartments through the combined use of bioimpedance and continuous blood pressure measurement techniques (5, 6) and, optionally, spirometry (7) and/or plethysmography.