During isometric relaxation, what is the status of the outflow valves?

During isometric relaxation, the outflow valves are indeed closed. This phase occurs after the contraction of the ventricles when the heart muscle relaxes but the volume within the ventricles remains the same. The closure of the outflow valves (the aortic and pulmonary valves) prevents blood from flowing back into the ventricles while they undergo relaxation, ensuring that the pressure within the ventricles decreases without any blood being ejected into the aorta or pulmonary artery. This helps maintain proper cardiac cycle dynamics, as the heart prepares for the next filling phase during diastole.

Understanding the closure of the outflow valves during isometric relaxation is crucial for comprehending the overall functioning of the cardiac cycle and the mechanics of heart pumping, which is fundamental knowledge for surgical practice and management of cardiac patients.