Mechanical Events Of The Cardiac Cycle

Question 0

Is the aortic semilunar valve open during ventricular systole ?

Answer 0

No because the aortic pressure is greater than the ventricular pressure

Question 1

Why is the AV valve open during ventricular diastole ?

Answer 1

Because atrial pressure is greater than ventricular pressure
- causes blood returning via the vena cava to passively enter right ventricule

Question 2

How much of ventricular filling occurs passively ?

Answer 2

70%

Question 3

What happens when ventricular pressure exceeds atrial pressure?

Answer 3

Av valves shut creating first heart beat sound - lub

Question 4

What is the isovolumic phase of contraction?

Answer 4

Both the av valves and semilunar valves are shut creating a little chamber

Question 5

When do the semilunar valves open ?

Answer 5

When ventricular pressure exceeds arterial pressure enabling blood to be ejected

Question 6

What causes the closure of the semilunar valves?

Answer 6

The back flow of blood in the aorta and the reduced ventricular pressure
Closure causes the 2nd heart sound dup

Question 7

What is the dichrotic notch ?

Answer 7

There is a slight rise in aortic pressure due to closure of semilunar valves causing the blood to rebound off the closed cusps

Question 8

What is isovolumic relaxation ?

Answer 8

After ejection of blood from the ventricles the semilunar valves close and currently the av valves are also closed creating another ventricular chamber

Question 9

How long is atrial systole ?

Answer 9

0.1 seconds

Question 10

How long is ventricular systole ?

Answer 10

0.3 seconds

Question 11

How long is the heart quiescent ?

Answer 11

0.4 seconds

Question 12

What is the systemic blood pressure average ?

Answer 12

120/80

Question 13

What is the pulmonary blood pressure ?

Answer 13

25/10

Question 14

What causes coronary artery disease ?

Answer 14

Accumulation of atherosclerotic plaques in coronary arteries which restrict blood flow

Question 15

What are the risk factors of coronary artery disease ?

Answer 15

High blood cholesterol 
Diabetes 
Smoking 
Genetic predisposition 
High blood pressure 
Obesity 
Sedentary lifestyle

Question 16

What is injected into patients with CAD ?

Answer 16

Streptokinase - break up blood clots

Question 17

What is used to detect blockages in coronary arteries ?

Answer 17

Angiography

Question 18

What are 2 routine procedures used to treat CAD ?

Answer 18

Percutaneous transluminal coronary angioplasty

Coronary artery bypass graft

Question 19

What is angioplasty ?

Answer 19

Inflate a balloon in coronary vessels to stretch the walls and squash plaques to widen the lumen
BUT damaged vessels can close again which is why stents are sometimes put in

Question 20

How does bypass grafting work ?

Answer 20

Usually use saphenous vein from leg

Put 2 to 4 grafts to bypass the blocked arteries

Question 21

What is ventricular septal defect ?

Answer 21

Hole in the interventricular septum - 1/500 births

Question 22

What is coarction of the aorta ?

Answer 22

Part of aorta is narrowed which increases load on left ventricle -1/1500 births

Question 23

What is tetralogy of fallot ?

Answer 23

Four simultaneous defects

• pulmonary trunk too narrow
• pulmonary valve stenosed
• aorta arises from both ventricles
• ventricular septal defect