Question

What happens in the outflow phase?

Answer 1

Cardiac cycle:

1. It is caused by a sequence of pressure shifts inside the heart.
2. These pressure variations cause blood to flow through various chambers of the heart and throughout the body.

There are four phases to the cardiac cycle:

1. Filling phase - During diastole and atrial systole, the ventricles fill.
2. Isovolumetric contraction - In preparation for pumping blood into the aorta/pulmonary trunk, the ventricles contract, raising pressure.
3. Outflow phase-The ventricles continue to contract, forcing blood into the aorta and the pulmonary trunk and this is also referred to as systole.
4. Isovolumetric relaxation — In preparation for the next filling phase, the ventricles relax.

Outflow phase:

1. When the pressure in the ventricles surpasses the pressure in the aorta/pulmonary trunk, the aortic/pulmonary outflow valves open, and blood is pushed from the heart into the major arteries.
2. Around 330ms after the end of systole, the ventricles begin to relax, lowering ventricular pressure in comparison to the aorta.
3. When the pressure drops, the valves close.
4. In addition, blood begins to flow backwards via the outflow valves, which adds to the closing of the valves.