Heart Sounds

• The heart contains heart valves that prevent the backflow of blood, ensuring one-way circulation around the body
• There are two sets of valves in the heart:

  • Atrioventricular valves (tricuspid and bicuspid) prevent blood in the ventricles from flowing back into the atria
  • Semilunar valves (pulmonary and aortic) prevent blood in the arteries from flowing back into the ventricles
• Heart sounds are produced when the atrioventricular and semilunar valves close in response to pressure changes within the heart
• The first heart sound is caused by the closure of the atrioventricular valves at the start of ventricular systole
• The second heart sound is caused by the closure of the semilunar valves at the start of ventricular diastole