Cardiac Cycle: Pressure and Volume Chahnges

Question 1

What are the atrioventricular valves?

Answer 1

Bicuspid (mitral) valve (LA-LV)
Tricuspid valve (RA-RV)

Question 2

What are the semi-lunar valves?

Answer 2

Pulmonary valve (RV-pulmonary artery)
Aortic valve (LV-aorta)

Question 3

What is the contractile phase called?

Answer 3

Systole

Question 4

What is the relaxation phase called?

Answer 4

Diastole

Question 5

Which is longer; diastole or systole?

Answer 5

Diastole

Question 6

What happens during passive filling?

Answer 6

AV valves: open
SL valves: closed

Question 7

What happens during atrial contraction?

Answer 7

AV valves: open
SL valves: closed

Question 8

What happens when pressure rises?

Answer 8

Flow rises

Question 9

Does the volume change?

Answer 9

Volume stays the same

Question 10

What happens during isovolumetric contraction?

Answer 10

AV valves: closed
SL valves: closed

Question 11

What happens during ventricular ejection?

Answer 11

AV valves: closed
SL valves: open

Question 12

What triggers the semi-lunar valves to open?

Answer 12

Pressure increases so blood needs to be ejected

Question 13

What happens during isovolumetric relaxation?

Answer 13

AV valves: closed
SL valves: closed

Question 14

When does ejection of blood occur?

Answer 14

When LV pressure exceeds aortic pressure

Question 15

What is normal stroke volume

Answer 15

~80ml

Question 16

What is the equation for cardiac output and what does it signify?

Answer 16

CO=HR x SV
Volume of blood each ventricle pumps per minute

Question 17

How do we find the stroke volume?

Answer 17

SV = EDV - ESV
EDV - end diastolic volume
ESV - end systolic volume

Question 18

When does the blood volume start to decrease?

Answer 18

As left ventricular pressure starts to exceed aortic pressure

Question 19

Where does the lub and dup sound come from?

Answer 19

Sound from the valves closing

Question 20

What side of the ventricles has higher pressure and why?

Answer 20

Left ventricle is higher
Left wall is thicker - needs a higher force of contraction due to having to eject blood against higher aortic pressure

Question 21

Are the left and right ventricles’ stroke volumes different or the same?

Answer 21

Stroke volumes are equal - same volume of blood being pumped

Question 22

What influences the fluctuation in atrial pressures during cardiac cycle?

Answer 22

Atrial/ventricular systolic and diastolic events
Atrioventricular valve events
Abnormal cardiac pump function

Question 23

What is the effect of valves being absent between the atria and their respective veins?

Answer 23

Venous pressure and atrial pressure are the same
Can assess jugular vein pressure for an insight into atrial pressure

Question 24

What does the a-wave refer to?

Answer 24

Right atrial contraction

Question 25

What does the c-wave refer to?

Answer 25

Bulging of tricuspid valve into right atrium and expansion of carotid artery
Beginning of systole - not contracting yet

Question 26

What does the x-descent refer to?

Answer 26

Right atrial relaxation and right atrial stretching
downward movement of the base of the ventricle

Question 27

What does the v-wave refer to?

Answer 27

Right atrial filling
v - ventricular systole

Question 28

What does the y-descent refer to?

Answer 28

Right atrial emptying into right ventricle

Question 29

Why is the tricuspid valve closed for a large part of the cardiac cycle?

Answer 29

Diastole phase is longer than systole phase