Cardiac Cycle

Question 1

Atrial systole?

Answer 1

Ventricles relax
Atria contract
Volume decreases, pressure increases (atria)
Pressure and volume increases (ventricles)
Pushes blood into the ventricles
AV valves are open, SL valves are closed

Question 2

Ventricular systole?

Answer 2

Ventricles contract, atria relax
Pressure and volume is low but volume begins to increase (atria)
Pressure increases, volume decreases (ventricles) - forces AV to shut to prevent back flow
Pressure increases ventricles is higher than in the aorta and pulmonary artery- SL valves open
Blood is forced out into the arteries

Question 3

Diastole?

Answer 3

Ventricles and atria both relax
High pressure in the pulmonary artery and aorta closes the SL valves to prevent backflow into the ventricles
Blood returns to the heart and the atria fill again due to the higher pressure in the vena cava and pulmonary vein
Pressure of atria increases
Ventricles continue to relax- pressure falls so AV open
Blood flows passively into the ventricles from the atria

Question 4

When do the AV valves open?

Answer 4

When the pressure is higher in the atria compared to the ventricles

Question 5

When do AV valves close?

Answer 5

When the pressure is higher in the ventricles compared to the atria

Question 6

When do SL valves open?

Answer 6

When the pressure is higher in the ventricle compared to the arteries

Question 7

When do SL valves close?

Answer 7

When the pressure is higher in the arteries compared to the ventricles