Explain5 marksStandard
During a cardiac cycle, the pressures in the left atrium, left ventricle, and aorta change as shown in the following data (typical values):
| Event | Left atrial pressure (mmHg) | Left ventricular pressure (mmHg) | Aortic pressure (mmHg) |
|---|---|---|---|
| Start of atrial systole | 5 | 0 | 80 |
| After atrial contraction | 8 | 5 | 80 |
| Ventricular systole begins | 6 | 120 | 80 |
| Ventricular systole peak | 4 | 120 | 120 |
| Ventricular diastole begins | 4 | 100 | 100 |
Using your knowledge of the cardiac cycle and the roles of the sinoatrial node, atrioventricular node, and Purkyne tissue, explain the sequence of events that determines when the mitral (bicuspid) valve and the aortic semilunar valve open and close during one heartbeat.