1.1.5 - Cardiac Cycle

Question 1

What Is The Cardiac Cycle?

Answer 1

A series of events that take place in one heart beat, including muscle contraction and relaxation.

Question 2

During Contraction Of The Heart, What Occurs?

Answer 2

Systole.

Question 3

During Relaxation Of The Heart, What Occurs?

Answer 3

Diastole.

Question 4

What Does Contraction Of The Heart Muscle Cause?

Answer 4

A decrease in volume in the corresponding chamber of the heart, which then increases again when the muscle relaxes.

Question 5

When The Volume Of Blood Decreases, What The Happens To The Pressure?

Answer 5

Pressure increases.

Question 6

When The Volume Of Blood Increases, What The Happens To The Pressure?

Answer 6

Pressure decreases.

Question 7

Why Causes Valves To Open?

Answer 7

They open due to pressure of blood behind them being greater than the pressure in front of them.

Question 8

Why Causes Valves To Close?

Answer 8

They close due to pressure of blood in front of them being greater than the pressure behind them.

Question 9

What Happens During Ventricular Diastole & Atrial Systole?
(4 Points)

Answer 9

~ Ventricles are relaxed, atria contract.

~ Decreasing volume and increasing pressure inside the chambers of the atria.

~ Pushing blood into the ventricles due to pressure in the atria rises above that in the ventricles, forcing the AV valves open.

~ There is a slight increase in ventricular pressure and volume as the ventricles receive the blood from the contracting atria.

Question 10

What Happens During Ventricular Systole & Atrial Diastole?
(6 Points)

Answer 10

~ Atria relax, ventricles contract

~ Increasing pressure, decreasing volume inside the ventricles.

~ The pressure in the ventricles rises above that in the atria, forcing the AV valves to close.

~ The pressure in the ventricles is higher than the aorta and the pulmonary artery, forcing the SL valves open to force blood into the arteries.

~ During this period the atria is relaxing.

Question 11

What Happens During Cardiac Diastole?
(6 Points)

Answer 11

~ Ventricles and atria are both relaxed.

~ The higher pressure in the pulmonary artery and aorta closes the SL valves, preventing back flow into the ventricles.

~ 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.

Question 12

During The Diastole Stage In The Cardiac Cycle, What Happens In Regards To The AV & SV valves?
(2 Points)

Answer 12

~ AV is open.

~ SV is closed.

Question 13

During The Systole Stage In The Cardiac Cycle, What Happens In Regards To The AV & SV valves?
(2 Points)

Answer 13

~ AV is closed

~ SV is open.

Question 14

What Occurs At Point A

Answer 14

End of cardiac diastole.

Question 15

What Occurs Between Points A & B?

Answer 15

Atrial systole.

Question 16

What Occurs At Points B & C?

Answer 16

Ventricular systole.

Question 17

What Occurs At Point D & E?

Answer 17

Cardiac diastole.

Question 18

Calculate The Heart Rate Of This Person. Give Your Answers In BPM
(4 Points)

Answer 18

~ 1 cardiac cycle = 0.7 seconds.

~ 1 / 0.7 =1.43 beats in 1s.

~ 1.43 x 60 =85.71 beats in 1m.

~ 85.71 BPM.