A simple lab exercise to challenge student's ability to predict changes in the functional state of the cardiovascular system

Abstract

Students routinely learn how separate properties comprising the functional state of the cardiovascular system will individually affect blood pressure, cardiac output, and tissue perfusion. The challenge is learning to integrate such compartmentalized understanding to interpret how the overall state adjusts based upon observed changes in dependent hemodynamic variables. A simple lab exercise facilitates integration of compartmentalized learning. A student rides a stationary bike while the workload is increased in steps with heart rate and blood pressure measured at each step. Students must then apply their knowledge of vascular hemodynamics and cardiac load to estimate changes in cardiac output and peripheral resistance from the observed changes in heart rate and blood pressure. They next explain how arteriolar vascular tone must be altered so as to maintain relatively stable diastolic arterial pressure while meeting the need for increased perfusion to the working muscle, followed by discussion of the expected changes in myocardial contractility and venous capacitance necessary to support increased circulatory flow. Control of state properties by autonomic reflexes is then discussed. As the intended outcome, students gain insight into the orchestrated changes in system properties that must occur as the body adjusts to moderate exercise, by predicting the new system state based upon observed changes in heart rate and blood pressure.