A&P CV 2 - Cardiac Cycle previous semester Flashcards
Cardiac Cycle
The cardiac cycle is:
the cardiac events from one beat to the next beat.
How many phases are in the cardiac cycle?
7 phases
In Atrial Systole is preceded by what? What does this represent?
P-wave; which represents electric activation of the atria.
In Atrial Systole is represented what letter on the venous pulse curve?
a
The increase in atrial pressure (venous pressure) is caused by
atrial systole (seen as the a on the venous pulse curve)
What is the cause of the 4th heart sound?
Filling of the ventricle by atrial systole
Is the 4th heart sound normal in adults?
No
Atrial Kick is associated with what?
Hypertrophic ventricle
S4 =
Atrial Kick
Name the 7 phases of the cardia cycle (in order)
- Atrial Stysole
- Isovolumetric Ventricular Contraction
- rapid ventricular ejection
- reduced ventricular ejection
- Isovolumetric ventricular relaxation
- Rapid ventricular filling
- Reduced ventricular filling (diastasis)
Phase 2 is
Isovolumetric ventricular contraction
Phase 2 Isovolumetric ventricular contraction begins after what? this represents what?
the QRS complex, which represents electrical activation of ventricles
In Phase 2, what happens with the pressures? This results in?
ventricular pressure becomes greater than atrial pressure, the AV valve closes.
Ventricular pressure increases ISOvolumetrically as a result of ventricular contraction.
When does the AV Valve close?
phase 2.
the first heart sound corresponds to?
The closure of the AV Valve
Does blood leave the ventricle in phase 2?
No - the aortic valve is closed.
Phase 3 is what?
Rapid Ventricular ejection
In phase 3, rapid ventricular ejection, the ventricular pressure reaches its what?
Max value
What happens in phase 3 with the pressures? What does this cause?
the ventricular pressure becomes greater than aortic pressure.
- the aortic valve opens.
- rapid ejection of blood into the aorta occurs.
In phase 3, what happens to the Volumes of the ventricle?
ventricular volume decreases
-b/c most of the SV is ejected in phase 3
What happens to the atria in phase 3
they begin to fill
Repolarization of the ventricles occurs in what phase? it is represented by what on EKG?
Phase 3
- T Wave
- marks the end of both ventricular contraction and rapid ventricular ejection
Which phase do we use to calculate SV?
Phase 3 - rapid ventricular ejection
Ventricular volumes decrease in phase
3
Atrial filling begins in phase
3
Repolarization of the ventricles occurs in phase
3
Phase 4 of cardiac cycle is:
Reduced ventricular ejection
What happens in phase 4?
- slower ejection of blood from ventricle continues
- ventricular pressure beings to decrease
- aortic pressure also decreases
- atrial filling continues
In phase 4, why does the aortic pressure decrease?
b/c of runoff of blood from large arteries into smaller arteries
In phase 4, ventricular pressures do what?
begin to decrease
aortic pressure decreases in what phase?
phase 4
Phase 5 of cardiac cycle is:
Isovolumetric ventricular relaxation
Repolarization of ventricles is complete in what phase?
5
What happens to the aortic and pulm valves in phase 5
aortic valve closes
followed by closure of pulm valve
- closure of the semilunar valves cooresponds to second heart sound
Second heart sound corresponds to what?
closure of the semilunar valves
What phase is the second heart sound audible in?
phase 5
What is the AV valve doing in phase 5?
it remains closed during most of this phase
In phase 5, what is happening to the ventricular pressure? why?
Ventricular pressure decreases rapidly bc ventricals are now relaxed
-when V.Pressure is LESS than A.Pressure the mitral valve opens
What phase are the ventricles relaxed?
phase 5
In phase 5, what is happening to the ventricular volume? why?
ventricular vol. is constant (ISOVOLUMETRIC) b/c ALL Valves are closed.
with all valves being closed in phase 5, what does this do the the volume in the ventricles?
it is constant, isovolumetric
In phase 5, when V.Pressure is < A.Pressure what happens?
the mitral valve opens
What is the dicrotic notch?
the “blip” in the aortic pressure tracing occuring after closure of the aortic valve
After the closure of the aortic valve, what is noted on the aortic pressure tracing?
the dicrotic notch
Is the dicrotic notch a normal finding?
Yes.
If not there, cardiac abnormality expected
End of the T wave is representative of what phase?
phase 5. repolarization of ventricles now complete
Phase 6 of cardiac cycle is:
Rapid ventricular filling
Rapid ventricular filling of phase 6 occurs when:
The mitral valve is open
-ventricular filling from the atrium begins
In phase 6 the aortic pressure:
continues to decrease
-because blood continues to run off into the smaller arteries
Rapid flow of blood from the atria into the ventricle causes what?
the third heart sound (S3)
S3 is normal or abnormal?
normal in children
associated with HF in adults
What sound is associated with HF in adults?
S3
S3 can be heard in children during what phase of they cardiac cycle?
Phase 6
Ventricular filling begins in…
phase 6
after the MV opens
The mitral valve opens in phase
6
Phase 7 in cardiac cycle is known as
Reduced Ventricular filling (Diastasis)
What is the largest phase of the cardiac cycle?
phase 7 - diastasis
Diastasis is phase
7
The ventricles are doing what in Diastasis?
ventricular filling continues, at a slower rate
the time required for Diastatsis (ventricular filling) depends on:
HR
If HR decreases, the ventricular filling time increases or decreases?
increases
If HR increases, the ventricular filling time increases or decreases?
decreases
Stroke Volume is the:
volume ejected from the ventricle on each beat
The volume ejected from the ventricle on each beat is the
Stroke Volume
Stroke volume equation is expressed as:
SV = end-diastolic volume - end systolic volume.
Normal SV is
75ml
Factors that INCREASE SV
anxiety, exercise, pregnancy
Myocardial O2 Demand is INCREASED by:
INCREASED -Afterload contractility HR Heart size (increased wall tension)
SV x HR =
CO
MAP = (equation w/o pulse p)
CO x Total Peripheral Resistance
Diastolic BP + 1/3 Pulse Pressure
MAP
Pulse Pressure =
SBP - DBP
SBP - DBP =
Pulse Pressure
Fick’s Principle is based off of
CO
Contractility, afterload and preload affect
Stroke Volume
Stroke Volume is affected by what components:
Contractility, afterload and preload
Contractility (and SV) increase with:
- Catecholamines
- increased intracellular CA++
- decreased extracellular Na+
- digitalis
Contractility (and SV) decreases with:
- ) beta-1 blockade
- HF
- Acidosis
- Hypoxia /hypercapnea
How do Catecholamines impact contractility? what do they do?
increase contractility
- increase activity of Ca ++ pump in SR
Digitalis impacts contractility- how?
increased contractility
-increases intracellular Na+ resulting in increased Ca++
Ejection Fraction is the (define)
the fraction of the end diastolic volume ejected in each stroke volume
Normal EF =
60%
an index of ventricular contractility is
Ejection fraction
“systolic function”
Ejection fraction
SV / End - diastolic volume = ?
Ejection fraction
Ejection fraction = (equation)
SV / End - diastolic volume
An EF = 40-50% means what?
blood is staying in the ventricle at the end of contraction