Cardiac cycle 2

Question 1

Outline cardiac cycle?

Answer 1

1. Atrial Systole- 0.1 sec
   Atrial depolarisation- atria contract (systole) completes ventricular filling
   P wave and PR interval
2. Isovolumetric Ventricular Contraction- 0.3 sec
   Ventricular systole
   Ventricular pressure greater than atrial pressure
   AV valve closes, semilunar valve still closed
   QRS complex
3. Rapid Ventricular Ejection
   Continued ventricular systole
   Ventricular pressure is greater than aortic pressure
   SL valves open
   Blood ejected
   Atrial filling begins
   ST segment
4. Reduced Ventricular Ejection
   Increased atrial pressure
   Ventricular repolarisation begins
   T wave
5. Isovolumetric Ventricular Relaxation
   Ventricles relaxed
   Aortic pressure greater than ventricular pressure
   Aortic valve closes (dicrotic notch)
   All valves are closed
   Complete ventricular repolarisation
   T wave ends

Question 2

What does the P wave and PR interval mark?

Answer 2

Atrial systole

Question 3

What stage does the AV open?

Answer 3

Atrial systole

Question 4

What represents ventricular systole?

Answer 4

QRS complex

Question 5

What occurs during ST segment?

Answer 5

Rapid ventricular ejection

Question 6

What wave does reduced ventricular ejection mark?

Answer 6

T wave

Question 7

What is phase called where all valves closed?

Answer 7

Isovolumetric Ventricular Relaxation

Question 8

Answer 8

Question 9

State 4 simplified stages of cardiac cycle?

Answer 9

Atrial systole- 0.1
- blood atria to ventricles
Ventricular systole- 0.3
- both ventricles contract blood forced out
Atrial diastole- 0.7
- relaxation atria- fill blood
Ventricular diastole- 0.5 ventricles passively fill blood

Question 10

How long is cardiac cycle? Why?

Answer 10

0.8 sec
Ventricular systole- 0.3
Ventricular diastole- 0.7