Understanding:
• Normal heart sounds are caused by the AV valves and semilunar valves closing causing changes in blood flow
The heart contains a number of heart valves which prevent the backflow of blood
- This ensures the one-way circulation of blood around the body
There are two sets of valves located within 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 made when these two sets of 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
Heart Valves and Heart Sounds