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Flashcards in Cardiac Cycle iBook Deck (24)
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Why is the volume of the ventricles never @ 0?

there is always some blood in the ventricles


Describe the ECG

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


What is the isoelectric line?

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


When is peripheral run-off @ its lowest?

When is peripheral run-off @ its slowest?

@ start of ECG when low aortic pressure

total peripheral resistance is high & blood moves to periphery slowly


What is diastolic BP?

aortic pressure measured as blood ejected into aorta from L ventricle

aortic & ventricular pressures are almost equal


What is systolic BP?

peak of aortic pressure (after opening of aortic valve)


What is the dicrotic notch?

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

pressure in aorta then drops as blood goes into periphery


When does the aortic valve open?

when pressure in ventricle exceeds that of the aorta


When does ventricular pressure decrease

after the peak systolic pressure occurs

occurs quickly once aortic valve closes


Which pressure remains low throughout the cardiac cycle?

atrial pressure


When does the atrial pressure increase?

shortly after P-wave occurs due to atrial contraction


What is the c-wave?

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


What occurs during isovolemic/isovolumetric contraction?

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

leads to slight increase in atrial pressure


What is the v-wave?

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


How does blood flow into ventricle from atria?

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


What is the end systolic volume (ESV)

lowest volume of the ventricle (50mL of blood)

measured after aortic valve closes


What is the end diastolic volume? (EDV)

volume of blood in ventricle when ventricle is full


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

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


What is isvolemic relaxation?

when ventricular volume doesn't change as ventricular pressure drops

aortic & pulmonary valves close before AV valves can open


When do the AV valves open?

when ventricular pressure drops below that in the atria


When does the first heart sound occur?

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


When does the second heart sound occur?

assoc w/ closing of aortic/pulmonic valves

when dicrotic notch occurs in aortic pressure wave


When does the third heart sound occur?

period of rapid filling & occurs early in diastole


When does the fourth heart sound occur?

assoc w/ blood being forced into ventricle during atrial contraction