- Atrial and ventricular diastole Blood flows into the atria.
- Elastic recoil of the atrial walls generates low pressure in the atria, helping to draw blood into the heart. Initially the atrioventricular valves are open/closed.
- As the ventricles begin to relax, blood tends to fall back from the aorta and pulmonary artery causing the semi-lunar valves to close.
- This causes the second…