Cardiac Cycle (not fin)

Question 1

Define systole

Answer 1

Contraction and ejection of blood from ventricles

Question 2

Define Diastole

Answer 2

Relaxation and filling of ventricles

Question 3

Define stroke volume

Answer 3

The volume of blood pumped at rest (per beat) which is ~70ml

Question 4

What is the heart valve that separates the right atrium from the right ventricle?

Answer 4

Tricuspid valve

Question 5

What is the valve that separates the left atrium from the left ventricle?

Answer 5

Mitral/bicuspid valve

Question 6

What is the valve that separates the right ventricle from the pulmonary artery?

Answer 6

Pulmonary valve

Question 7

What is the valve that separates the left ventricle from the aorta?

Answer 7

Aortic valve

Question 8

How is inversion of valves prevented?

Answer 8

Mitral and tricuspid valves are attached to papillary muscles by chordate tendinae

Question 9

Describe the conduction system of the heart

Answer 9

1) Sinoatrial node generate an AP = atrial systole
2) Signal area he’s atrioventricular node and delays
3) AP down septum to ventricles then spread (from endocardium/inner to epicardial/outer surface)

Question 10

What does the Wiggers diagram show?

Answer 10

Pressure changes during one full cardiac cycle (typically for the left side of the heart)

Question 11

What are the seven phases of the cardiac cycle (in order)?

Answer 11

1) Atrial contraction
2) Isovolumetric contraction
3) Rapid ejection
4) Reduced ejection
5) Isovolumetric relaxation
6) Rapid filling
7) Reduced filling

Question 12

What happens in Atrial contraction?

Answer 12

• P wave in ECG
• A wave shows atrial pressure rising due to atrial systole
• Accounts for final ~10% of ventricular filling
• Ventricular volumes are maximal at the end
• Mitral/Tricuspid=open ; aortic/pulmonary=closed

Question 13

What happens in Isovolumetric contraction?

Answer 13

• QRS complete in ECG
• C wave shows intraventricular pressure exceeding atrial pressure
• Mitral/Tricuspid valve closes causing the first heart sound (S1)
• Pulmonary/aortic still closed

Question 14

What happens in Rapid ejection?

Answer 14

• intraventricular pressure exceeds aortic pressure
• Aortic/pulmonary valve opens
• X descent = initial decrease in atrial pressure as atrial base is pulled down as ventricles contract
• Mitral/Tricuspid=closed ; Aortic/pulmonary=open

Question 15

What happens in Reduced ejection?

Answer 15

• T wave in the ECG
• V wave shows atrial pressure rises due to continued venous return from lungs
• decline in tension and fall in rate of ejection due to repolarization of ventricle

Question 16

What happens in Isovolumetric relaxation?

Answer 16

• IV pressure falls below aortic, brief back flow causes aortic valve closure (causes dicrotic notch in aortic pressure)
• volume remains constant as valves are closed (even if there’s rapid decline)
• Mitral/tricuspid=closed, aortic/pulmonary=closed