foundation

vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonic valve -> pulmonary artery -> pulmonary vein -> left atrium -> mitral valve -> left ventricle -> aortic valve -> aorta -> systemic circulation

• Tricuspid valve
• Mitral valve

• Pulmonic valve
• Aortic valve

• First heart sound
• Closure of mitral and tricuspid valves
• Marks beginning of ventricular systole
• Occurs right after QRS complex

• Second heart sound
• Closure of aortic and pulmonic valves

• Approx 2/3 of cardiac cycle
• Relaxation and filling of atria and ventricles

Contraction and emptying of atria and ventricles