The Cardiac Cycle

Question 1

1. Ventricles Relax Atria Contracts

Answer 1

-As the Ventricles Relax, the Atria contract, decreasing volume in the chambers and increasing pressure in the chambers
-Pushing Blood into the ventricles
-INCREASE in ventricular pressure and chamber volume AS atria contacts and blood is ejected into the ventricles

Question 2

Ventricles Contract Atria Relaxes

Answer 2

-As the Atria are relaxed, the Ventricles contact
-Decreases V Volume and Increases Pressure
-Higher pressure in Ventricles than Atria forces AV valves shut (preventing back-flow)
-Pressure is Also higher in ventricles than aorta and pulmonary artery, forcing SL valves open and blood is forced out into these arteries

Question 3

Ventricles Relax and Atria Relax

Answer 3

-Both Ventricles and Atria relax
-Higher pressure in pul. artery and aorta closes SL valves to prevent back-flow into the ventricles
-Blood returned to the heart, higher pressure in vena cava and pulmonary vein so atria fill again
-Ventricles continue to relax, pressure falls below the atria pressure, AV valves open.
-Allows blood to flow without atrial contraction to the ventricles passively
-Atria contracts and process repeats