Ancestors of Thermodynamics P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Beak through Inventions for Formulation of Thermodynamics …..
The Family of Steam Engines A Hardware Responsible for the Greatest Engineering Science
Description of Heart Cycle • A is the end-diastolic point; this is the point where contraction begins. • Pressure starts to increase, becomes rapidly higher than the atrial pressure, and the mitral valve closes. • Since pressure is also lower than the aortic pressure, the aortic valve is closed as well. • Segment AB is the contraction phase. • Since both the mitral and aortic valves are closed, volume is constant. • For this reason, this phase is called isovolumic contraction. • At point B, pressure becomes higher than the aortic pressure and the aortic valve opens, initiating ejection.
BC is the ejection phase, volume decreases. • At the end of this phase, pressure lowers again and falls below aortic pressure. • The aortic valve closes. • Point C is the end-systolic point. • Segment CD is the isovolumic relaxation. • During this phase, pressure continues to fall. • The mitral valve and aortic valve are both closed again so volume is constant. • At point D pressure falls below the atrial pressure and the mitral valve opens, initiating ventricular filling. • DA is the diastolic filling period. • Blood flows from the left atrium to the left ventricle. • Atrial contraction completes ventricular filling.