CVS physiology Flashcards
Increase in stroke volume (SV) is due to increased stretch is
Frank Starling mechanism
what is the Frank Starling relationship?
the volume of blood ejected by the ventricle (SV) depends on the volume present in the ventricle at the end of diastole.
what is the Frank Starling mechanism (relationship)?
the force of systolic contraction is proportional to the initial length of cardiac muscle in diastole (preload/stretch).
ratio of stroke volume (SV) to EDV is
ejection fraction (EF) EF= SV/EDV
what is contractility?
the amount of force cardiac muscle can generate at a given muscle length, and is related to intracellular [Ca2+]. it can be estimated by ejection fraction (EF)
increased SV w/ no change in EDV is
contractility. Increase SV w/ no change in EDV, results in increased EF. EF is an estimate of contractility, so contractility also increases
what is preload?
the load seen by cardiac myocytes while the heart is in its relaxed state (ventricular diastole). it represents the stretch on the filled ventricle during diastole, before contraction takes place.
what is afterload?
the load against which the myocytes must contract to generate CO.
what is a measure of afterload?
blood pressure (BP)
what would an acute increase in afterload produce?
a reduced volume of blood ejected during systole.
Systole occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is F
F. phase 6 is F
G. phase 7 is G
Systole occurs during phase 2.
Also present during phase 2 are: QRS complex, Period of highest O2 consumption, Excitation-contraction coupling, Maximal dP/dT, Isovolumetric contraction, All 4 valves are closed (MV, TrV, AoV, and PV are closed) and Ventricles contract
MV and TrV closure produces the S1 heart sound
MV closes before TrV , so S1 maybe split
Ventricular systole
Aortic (Ao) valve opens
Aortic valve is open for most of ventricular systole
A C wave noted in the left atrial pressure (LAP) may be due to bulging of MV leaflets back into the left atrium (mitral valve regurgitation)
After the C wave peak is the x-descent.
Rapid ejection phase is
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
C. phase 3 is C
rapid ejection occurs during phase 3
Ao and P valves open
Rapid ejection phase
Blood rushes out of the ventricles into the aorta/pulmonary a. and onto the system/lungs respectively.
NO heart sounds
Presence of heart sounds in phase 3 ejection murmurs is sign of valve disease.
Atrial systole occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
A. phase 1 is A
phase 1 is atrial systole, ventricular diastole
Events of phase 1 (A):
Diastolic filling of the ventricles
Mitral (M) and Tricuspid (T) valves open
Atrial depolarization Atrial systole (contraction)
S4 heart sound- It’s caused by vibration of the ventricular wall during atrial contraction
It’s not audible in normal adults; S4 heart sound in adults is sign of: High atrial pressure
and/or Stiff ventricle. S4 sound is present in individuals w/ ventricular hypertrophy and.or older individuals
Pressure increases in the ventricles
atrial contraction does produce a small increase in venous pressure that can be noted as the “a-wave” of the left atrial pressure (LAP). Just following the peak of the a wave is the x-descent.
Maximal ventricular volume
End-diastolic volume (EDV) is maximal ventricular volume
LVEDV ≈ 120 ml
Ventricular preload is the LVEDV
Ventricle contracts (QRS complex)
QRS complex is ventricular systole and atrial diastole
isovolumetric contraction occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
B. phase 2 is B
isovolumetric contraction occurs during phase 2.
this is ventricular systole and atrial diastole
aortic valve is open for most of ventricular systole
MV and TrV close (S1 heart sound)
MV closes before TrV , so S1 maybe split
S of QRS complex occurs here
Rapid ejection occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
C. phase 3 is C
Rapid ejection occurs in phase 3
In the rapid ejection phase (phase 3):
Ao and P valves open
Blood rushes out of the ventricles into the aorta/pulmonary a. and onto the system/lungs respectively.
NO heart sounds
Presence of heart sounds in phase 3, ejection murmurs, is a sign of valve disease.
reduced ejection occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
D. phase 4 is D
Reduced ejection occurs during phase 4.
In the reduced ejection phase (phase 4):
Reduced ejection of the ventricles
Ventrical repolarization (T wave)
Ao and P valves still open
M and T valves still closed
Atrial pressure gradually increases
Continued venous return (VR)
NO heart sounds in phase 4
Presence of heart sounds in phase 4 (ejection murmurs) is sign of valve disease.
isovolumetric relaxation occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
E. phase 5 is E
Isovolumetric relaxation occurs in phase 5
in the isovolumetric relaxation phase:
AoV and PV close (S2 sound)
AoV closes before PV
Inspiration causes increases splitting of S2
Inspiration decr. Intrathoracic pressure, which incr. venous return (VR) to the heart and delays PV closure.
S2 splitting is normal in athletic individuals and kids
Dicrotic notch at start of phase 5
It occurs after the valves close
It’s due to small backflow of blood into the ventricles.
Isovolumetric relaxation
Ventricles relax
All 4 valves are closed
End-systolic volume (ESV)=remaining volume of blood in the ventricle
LVESV≈50 ml Stroke volume (SV)=EDV-ESV=
EDV=end-diastolic volume
CO=cardiac output
HR=heart rate
Ejection fraction (EF)=
At the end of phase 5, atrial pressure exceeds ventricular pressure
Atrial pressure increases due to venous return (VR)
V-wave=peak left atrial pressure (LAP) at end of phase 5
rapid ventricular filling occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
F. phase 6 is F
Rapid ventricular filling occurs during phase 6.
in the rapid ventricular filling phase:
V-wave=peak left atrial pressure (LAP) just before MV opens
This is followed by the y-descent of the LAP
MV and TrV open
Rapid ventricular filling
S3 heart sound
It’s normal in children and pregnant women
In anyone else, it’s a sign of dilated CHF/ventricular dilation
reduced ventricular filling occurs during
A. phase 1 is A
B. phase 2 is B
C. phase 3 is C
D. phase 4 is D
E. phase 5 is E
F. phase 6 is F
G. phase 7 is G
G. phase 7 is G
reduced ventricular filling occurs during phase 7
in the reduced ventricular filling phase:
MV and TrV are still open
In normal resting hearts, the ventricles are 90% filled by the end of phase 7
this is a normal 12-lead ECG. label each of the parts:
P wave, QRS complex, T wave, QT interval, ST interval
describe what happens at P wave, QRS, ST interval, QT interval, and T wave
Each heart beat begins in the rt atrium w/ a signal (AP) from the SA node
AP spreads from the SA node to the AV node causing atrial depolarization
P wave=atrial depolarization phase
P wave demonstrates atrial muscles contract (atrial systole)
PR interval
It’s the period of conduction after atrial systole but before ventricular systole (contraction)
The signal leaves atria and goes to AV node and then to bundle of His then to bundle branches
Incr. conduction velocity, incr. decr PR interval
Decr. Conduction velocity, incr. PR interval
QRS complex
Ventricular systole (ventricular contraction)
Signal enters ventricles via AV node
Ventricle depolarization
Atrial repolarization
It’s hidden by QRS complex
Normal QRS ≤0.10s
ST interval- period when ventricles are depolarized
Ventricular walls relax
QT interval
It’s the time it takes for depolarization and repolarization of the ventricles to occur.
Corrected QT =(QT*)
QT*=QT/sqrt (R-R)
R-R=distance betw. 2 QRS complexes
QT*≤ 0.44s
when does the aortic valve open
A
B
C
D
E
C.
aortic valve opens at C just before the systolic ejection phase (D)
when does the aortic valve close?
A
B
C
D
E
E
the aortic valve closes after systolic ejection but before isovolumetric relaxation. aortic and pulmonic valve closing creates the S2 sound.
when does the mitral valve open?
A
B
C
D
E
A
the mitral valve opens during the reduced filling phase
when does the mitral valve close?
A
B
C
D
E
B
the mitral valve closes just before isovolumetric contraction (systole)
