Lecture 6 Flashcards
Which valves are between the great veins and atria?
there are none!
What causes heart valves to close
pressure differential
papillary muscles do not help close- they prevent bulge
pressure in distal chamber exceeds proximal chamber
valves close
pressure in proximal chamber exceeds distal chamber
valves open
Atrial systole
ventricular filling completely via atrial contraction (20% at rest…the rest is done passively)
Ventricular systole (3)
Isovolumetric contraction
Rapid ejection
Reduced ejection
ventricular diastole (3)
isovolumetric relaxation
rapid ventricular filling
reduced ventricular filling
End of diastole (3)
all chambers relaxed
AV valves open (atrial pressure slightly higher than ventricular)
Pulmonary and aortic valves closed (aoritc and pulmonary pressure higher than ventricular)
A wave of venous pressure reflects
Atrial systole
EDV
the volume of blood in the ventricle at the end of atrial systole
ventricular systole- isovolumetric contraction(4)
inc in ventricular pressure
QRS complex-ventricular depolarization
Rise in pressure -> AV valve closing
AV valves bulge into atria-> atrial pressure wave (c wave)(think Contraction of ventricles)
Ventricular Systole- rapid ejection(2)
ventricular pressure inc above diastolic arterial pressure
semilunar valves open- blood flows into arteries
Ventricular systole- reduced ejection(3)
almost no blood flow, but ventricle remains contracted
eventually flow briefly reverses-> closure of aortic and pulmonary valves
Abrupt closure of aortic valve causes dichrotic notch
end of ventricular systole
build up of blood(from veins) in atria causes atrial v wave
SV
volume of blood ejected
SV=EDV-ESV
Ejection fraction
proportion of EDV ejected
EF=SV/EDV
is diastole or systole longer
at rest diastole (ventricular) is 2x length of systole
ventricular diastole- isovolumetric relaxation
closure of outflow valves
ventricular diastole- rapid ventricular filling
ventricular pressure falls below atrial pressure, AV valves open and atrial pressure falls rapidly as ventricles fill
ventricular diastole- reduced refilling
ventricles relax completely and refilling slows
pressure volume loops
can be used to describe changes occurring in disease states that affect either filling or pumping
Systolic pressure
peak pressure at point of maximal ejection of blood from ventricle
diastolic pressure
pressure when outlet valves are closed
Major difference between right and left heart in regards to pressures
right heart= magnitude of systolic pressures. lungs have much lower resistance to flow, so less arterial pressure required
1st and 2nd heart sounds mark
the beginning and end of ventricular systole
1st sound
closure of AV valves(bi and tricuspid)
2nd sound
closure of outlet valves (pulmonic and aortic)
3rd heart sound
generally weak and difficult to hear (except horses)
mid diastole-vibrations due to entry of blood to ventricle
4th sound
occurs with atrial contraction
similar to 3rd heart sound
murmur- gallop rhythm
splitting of the 1st and 2nd heart sounds producing triple instead of double sound
Measures of the heart’s performance(3)
SV(=EDV-ESV)
HR
CO (=HRxSV)
