Doctors use a stethoscope to hear the sounds produced during each cardiac cycle. The second sound is heard when:
1. | AV valves open up |
2. | Ventricular walls vibrate due to the gushing of blood from the atria |
3. | Semi-lunar valves close down after the blood flows into vessels from the ventricles |
4. | AV node receives a signal from SA node |
Blood pressure in the mammalian aorta is maximum during:
In humans, blood passes from the post caval to the diastolic right atrium of heart due to:
1. pushing open of the venous valves
2. suction pull
3. stimulation of the sino auricular node
4. pressure difference between the caval and atrium