- Blood is forced through the tricuspid and bicuspid valves into the ventricles.
Phase 2: Ventricular systole (Ventricle contracts)- Ventricles relax and fill with blood.
- The ventricles contract for 0,3 seconds.
- Blood is forced upwards, closing the bicuspid and tricuspid valves (lubb sound).
- The blood travels up into the pulmonary artery (on the right) and the aorta (on the left).
- The atria are relaxed during ventricular systole.
Phase 3: General diastole: (General relaxation of the heart)- The ventricles relax, thus decreasing the flow from the ventricles.
- Once there is no pressure the blood flow closes the semi-lunar valves in the aorta and
the pulmonary artery (dubb sound). - General diastole lasts for about 0,4 seconds.
Figure 8.10: The cardiac cycle of contraction and relaxation of heart muscles during pumping of
blood throughout the body.See video: SHORTCODEat http://www.everythingscience.co.zaThe sound the heart makes232 8.2. Circulatory systems in animals