1.1.5 - Cardiac Cycle Flashcards
What Is The Cardiac Cycle?
A series of events that take place in one heart beat, including muscle contraction and relaxation.
During Contraction Of The Heart, What Occurs?
Systole.
During Relaxation Of The Heart, What Occurs?
Diastole.
What Does Contraction Of The Heart Muscle Cause?
A decrease in volume in the corresponding chamber of the heart, which then increases again when the muscle relaxes.
When The Volume Of Blood Decreases, What The Happens To The Pressure?
Pressure increases.
When The Volume Of Blood Increases, What The Happens To The Pressure?
Pressure decreases.
Why Do Valves Open?
They open due to pressure of blood behind them being greater than the pressure in front of them.
Why Do Valves Close?
They close due to pressure of blood in front of them being greater than the pressure behind them.
What Do Valves Prevent?
The back flow of blood.
What Happens During Atrial Systole?
(5 Points)
~ The walls of the atria contract.
~ Atrial volume decreases.
~ Atrial pressure increases.
~ The pressure in the atria rises above that in the ventricles, forcing the AV valves open.
~ Blood is forced into the ventricles.
What Happens During Ventricular Systole?
(6 Points)
~ The walls of the ventricles contract.
~ Ventricular volume decreases.
~ Ventricle pressure increases.
~ The pressure in the ventricles rises above that in the atria, forcing the AV valves to close.
~ The pressure in the ventricles rises above that in the aorta and the pulmonary artery, forcing the semilunar valves open to force blood into the arteries.
~ During this period the atria is relaxing.
What Happens During Diastole?
(6 Points)
~ Ventricles and atria are both relaxed.
~ Pressure in the ventricles drop below that in the aorta and pulmonary artery, forcing the SL valves to close.
~ The atria continue to fill with blood and also blood returns to the heart via the vena cava and pulmonary vein.
~ Pressure in the atria rises above that in the ventricles, forcing the AV valves open.
~ Blood flows passively into the ventricles without the need of atrial systole.
~ The cycle begins again with atrial systole.
During The Diastole Stage In The Cardiac Cycle, What Happens In Regards To The AV & SV valves?
~ AV is open.
~ SV is closed.
During The Systole Stage In The Cardiac Cycle, What Happens In Regards To The AV & SV valves?
~ AV is closed
~ SV is open.
