Cardiac Cycle iBook

Question 1

Why is the volume of the ventricles never @ 0?

Answer 1

there is always some blood in the ventricles

Question 2

Describe the ECG

Answer 2

P wave=atrial depolarization
PR interval=time for AV node transmission
QRS complex=ventricular depolarization
ST segment=when ventricular mycytes @ plataeu
T wave=ventricular repolarization

Question 3

What is the isoelectric line?

Answer 3

time btwn beats, when all chambers of heart are in diastole

Question 4

When is peripheral run-off @ its lowest?

When is peripheral run-off @ its slowest?

Answer 4

@ start of ECG when low aortic pressure

total peripheral resistance is high & blood moves to periphery slowly

Question 5

What is diastolic BP?

Answer 5

aortic pressure measured as blood ejected into aorta from L ventricle

aortic & ventricular pressures are almost equal

Question 6

What is systolic BP?

Answer 6

peak of aortic pressure (after opening of aortic valve)

Question 7

What is the dicrotic notch?

Answer 7

blip in aortic pressure wave produced by closing of aortic valve as ventricle relaxes

pressure in aorta then drops as blood goes into periphery

Question 8

When does the aortic valve open?

Answer 8

when pressure in ventricle exceeds that of the aorta

Question 9

When does ventricular pressure decrease

Answer 9

after the peak systolic pressure occurs

occurs quickly once aortic valve closes

Question 10

Which pressure remains low throughout the cardiac cycle?

Answer 10

atrial pressure

Question 11

When does the atrial pressure increase?

Answer 11

shortly after P-wave occurs due to atrial contraction

Question 12

What is the c-wave?

Answer 12

small sharp increase in atrial pressure that coincides w/ start of ventricular contraction

Question 13

What occurs during isovolemic/isovolumetric contraction?

Answer 13

ventricular pressure is increasingly rapidly & causes AV valve to bulge back into atria

leads to slight increase in atrial pressure

Question 14

What is the v-wave?

Answer 14

increase in atrial pressure b/c AV valve is closed & venous blood is accumulating in atria

Question 15

How does blood flow into ventricle from atria?

Answer 15

b/c during diastole & atrial systole, atrial pressure is greater than that inside the ventricle

Question 16

What is the end systolic volume (ESV)

Answer 16

lowest volume of the ventricle (50mL of blood)

measured after aortic valve closes

Question 17

What is the end diastolic volume? (EDV)

Answer 17

volume of blood in ventricle when ventricle is full

Question 18

What is unique about the ventricular systole (isovolumetric contraction)?

Answer 18

ventricle is contracting isometrically to increase pressure b/c neither the AV nor the aortic/pulmonary valves are open

Question 19

What is isvolemic relaxation?

Answer 19

when ventricular volume doesn’t change as ventricular pressure drops

aortic & pulmonary valves close before AV valves can open

Question 20

When do the AV valves open?

Answer 20

when ventricular pressure drops below that in the atria

Question 21

When does the first heart sound occur?

Answer 21

assoc w/ closing of AV valves (start of isovolemic contraction)

Question 22

When does the second heart sound occur?

Answer 22

assoc w/ closing of aortic/pulmonic valves

when dicrotic notch occurs in aortic pressure wave

Question 23

When does the third heart sound occur?

Answer 23

period of rapid filling & occurs early in diastole

Question 24

When does the fourth heart sound occur?

Answer 24

assoc w/ blood being forced into ventricle during atrial contraction