CARDIAC CYCLE AND HEART SOUNDS

• Cardiac cycle - refers to one complete heartbeat, in which both atria and ventricles contract then relax
• Systole - contraction

  Diastole - relaxation
• Average heart rate - 75 bpm

  Cardiac cycle length - 0.8 seconds
• Heart sounds

  • Lub - longer, louder, caused by closing of the AV valves
  • Dup - short, sharp, caused by closing of the semilunar valves