The central hypothesis tested in this thesis is that heart rate and blood pressure are by-products of the control loops in the cardiovascular system. Two complementary approaches were used in investigating this issue: I. Analyses of data obtained from patients undergoing carotid surgery, during which perturbations to the baroreceptors cause fluctuations in heart rate and blood pressure; 2. Design and analysis of a control model of the cardiovascular system with its autonomic and baroreflex regulation.