Physiology Lecture 1 -- The Heart as a Pump Flashcards
When does first heart sound (S1) occur?
Mitral valve closes
When does S2 occur?
Aortic valve closes
When can S3 occur in terms of Wigger’s diagram?
After early rapid/brisk filling via the LA-LV P gradient
What is the most common reason for S3 being abnormal?
Congestive heart failure causing increased ventricular pressure (a poor prognostic factor)
Define systole in terms of heart events
Mitral valve closes –> aortic valve closes
Define diastole in terms of heart events
Aortic valve closes –> mitral valve closes
Explain the purpose of isovolumetric contraction
Both valves are closed, so no blood flow occurs as pressure builds in the ventricle to overcome the pressure of the aorta = establish P gradient
Pressure gradient during ejection
Left ventricle > Aorta
Explain the purpose of isovolumetric relaxation
Both valves are closed, so no blood flow as the left ventricle is given time to relax until its pressure is lower than the atrium
Pressure gradient during diastole (post isovolumetric relaxation)
Left atrium > Left ventricle
What physical event causes the mitral valve to close?
When P left atrium was higher than P left ventricle and then their P become equal
What physical event causes the aortic valve to close?
When P left ventricle was higher than P aorta and then their P become equal
What physical event causes the aortic valve to open?
When P aorta was higher than P ventricle and then their P become equal
What physical event causes the mitral valve to open?
When P ventricle was higher than P atrium and then their P become equal
When can a fourth heart sound be heard?
During the atrial kick
How much of the blood is passively emptied from the left atrium to the left ventricle during diastole?
70%
What is the purpose of the atrial kick?
Contraction of the atrium to force the remaining 30% of the blood to enter the left ventricle
What wave in the wigger’s diagram indicates the atrial kick?
a wave
What event does the x descent of the Wigger’s diagram represent?
Atrial relaxation (early systole)
What event does the v wave of the Wigger’s diagram represent?
Atrial filling
What event does the y descent of the Wigger’s diagram represent?
Atrial emptying (early diastole)
What might cause an opening heart sound?
Bicuspid aortic valve (an ejection sound)
Define this event

Aortic valve closes
Define this event

Aortic valve opens
Define this event and associated wave

A Wave = Atrial Kick
Define this time interval

Atrial systole
Define this time interval

Diastalsis
Define this interval

Diastole
Define this interval

Ejection
Define this interval

Isovolumetric contraction
Define this interval

Isovolumetric relaxation
Define this event

Mitral valve close
Define this event

Mitral valve open
Define this interval

Rapid inflow
Define this interval

Systole
Define this wave

v wave = atrial filling
Define this wave

x descent = atrial relaxation
Define this wave

y descent = atrial emptying
Define ESV
Ventricular volume at the end of systole (when aortic valve closes
Define EDV
Ventricular volume at the end of diastole (mitral valve closes)
Defien inotropy
Contractility, reflected by the relationship between ESV and afterload
Define preload
The ventricular volume of blood prior to systole (same as EDV)
Define afterload
The pressure (of aorta) that the left ventricle must overcome during systole to eject blood
Describe the significance of the relatively shallow slope of the ventricular fillling line of the PV loop
Low slope = low P for changes in V = good compliance
Define diastology
PV relationship during diastole (V filling property; compliance)
An example of a heart with decreased compliance
Hypertension (thickened ventricular wall)
An example of a heart with increased compliance
Cardiomyopathy
What happens if left ventricular pressure cannot overcome aortic P
No ejection = keep contracting isovolumetrically
Define SV
Stroke Volume = EDV - ESV
Amount of blood ejected to the aorta
Define ejection fraction
EF = SV/EDV
Proportion of blood ejected to aorta that was in the ventricle
3 factors that affect ventricular performance
Contractility
Afterload
Preload
Effect of increased preload on isovolumetric pressure
Increase
Define systology
End systolic pressure volume relationship (contracility)
Effect of inotropy with constant afterload and preload

Positive inotropic agent = increase contractility = increase SV (blue)
Negative inotropic agent = decrease contractility = decrease SV (red)
Predict effect of preload based on Starling’s Laws
If V is increased, a NORMAL heart will has more vigorous contractions and produce higher pressures
Define premature ventricular contraction
Compensatory pause, which signifies filling of the ventricle = bigger ventricle = very forceful contraction
Effect of preload with constant inotropy and afterload
Increased preload = increased SV
Normal ejection fraction
60%
Effect of afterload (aortic P) with constant preload and inotropy
Increased afterload = decreased SV = lowered EF (since higher ESV)
How to treat patients with too much afterload
Decrease afterload with vasodilator (ACE inhibitor), which “unloads” the heart
Effect of heart failure on PV loops
Decrease contraciltiy and increased EPV –> decreased SV

Afterload
Define this event

Aortic valve opens
What does this space represent?

Diastole
What does this corner represent?

Mitral valve closes
EDV = preload
What does this corner represent?

ESV
Aortic valve close
What does this slope represent?

Inotropy
What does this edge represent?

Isovolumetric contraction
What does this edge represent?

Isovolumetric relaxation
What does this space represent?

Systole
What does this corner represent?

Mitral valve opens
What does this width represent?

SV