Lecture 7 Flashcards
With valves closed, pressure develops during?
Myocardial Contraction
When ventricular chamber pressure exceeds aortic blood pressure?
Valves open
Blood moves according to?
Pressure gradient (because valves)
Open Valve?
Ejection
Closed Valve?
Filling
(Cardiac Cycle)
Pressure Changes?
(Left)
-Atria
-Ventricle
-Aorta
(Cardiac Cycle)
Volume Changes?
Ventricle
(Cardiac Cycle)
Electrical Changes?
-Atria
-Ventricle
(Cardiac Cycle)
Valve Opening/Closing?
-Aortic Valve (and Pulmonary)
-AV valves (tricuspid/mitral)
Phonocardiogram?
Measuring audible sound
(Cardiac Cycle)
7 Phases?
1) Atrial systole
2) Ventricular isovolumetric contraction
3) Rapid ventricular ejection
4) Slow ventricular ejection
5) Ventricular isovolumetric relaxation
6) Ventricular filling
7) Diastasis
Phase 1?
Atrial Systole
Phase 2?
Ventricular isovolumetric contraction
Phase 3?
Rapid ventricular ejection
Phase 4?
Slow ventricular ejection
Phase 5?
Ventricular isovolumetric relaxation
Phase 6?
Ventricular filling
Phase 7?
Diastasis
Phase 1 (Atrial Systole)?
(Depolarization)
-P-wave (Atrial depolarization precedes and triggers atrial contraction)
-“a”-wave (developed atrial pressure)
-Blood moves from atrial chamber and further fills ventricle (increased pressure)
((Mitral) AV valves close: Causes 1st heart sound, Ends phase 1)
Phase 2 (Isovolumic Contraction)?
(No change in blood volume in chambers)
-QRS-wave (Ventricular depolarization precedes and triggers rapid ventricular contraction)
-Contraction causes a rapid rise in developed ventricular pressure
-With both input (A-V) and output (aortic) valves closed, no blood moves
(Aortic valve opens: Ending Phase 2)
Phase 3 (Rapid Ejection)?
-With ventricular pressure greater than aortic pressure, the aortic valve opens and blood is rapidly ejected from ventricle into aorta, producing a rise in “systolic” aortic pressure
-Ventricular contraction is transmitted mechanically to atria producing “c-wave” in atrial pressure
-T-wave: Ventricular repolarization initiates ventricular relaxation and ends Phase 3
Phase 4 (Reduced Ejection)?
-Ventricular relaxation causes a decrease in ventricular pressure
-Ventricle slowly empties
-Continuous return of venous blood begins atrial filling and increased atrial pressure
-Aortic Valve Closes: causes 2nd Heart Sound Ending Phase 4 (all covered due to sound)
Phase 5 (Isovolumic Relaxation)?
-Ventricular relaxation (and empty ventricular chamber) causes a rapid drop in ventricular pressure
-Both input (A-V) and output (aortic) valves are closed, no ventricular blood moves
-A-V Valve Opens: Ending Phase 5
Phase 6 (Ventricular Filling (Rapid Flow))?
-Ventricular pressure is below atrial pressure, so with the opening of A-V Valve, atrial blood rapidly flows into ventricle (turbulent sound)
-3rd Heart sound is caused by rapid turbulent flow (NOT due to any valves) (louder if ventricle decreases compliance)
Phase 7 (Diastasis)?
-A-V Valve is open, and venous blood is slowly filling both the atrial and ventricular chambers
-Decreased, slow ventricular filling
-Aortic pressure slowly declines as aortic blood is distributed to peripheral tissues
-Atrial contraction (systole) ends Phase 7
Heart mechanically operates within limits of P-V relations established by?
Passive and Active properties of myocardial tissue
EDV - ESV = ?
SV (Stroke Volume)
Increase Length = Increase Volume = ?
Increase Preload
Increased active force due to greater?
Cross-Bridge Overlap
Preload uses what ventricle and measures what?
-End Diastolic Volume
-Right atrial pressure, left ventricle and diastolic pressure, pulmonary capillary wedge
Afterload uses what ventricle and measures what?
-Aortic pressure
-Mean arterial pressure
(Length-Tension (Frank-Starling) Relationship)
4 –> 1?
-Increasing length by stretching increases “passive” force
-Corresponds to Preload, and degree of stretch “sets” the level of cross-bridge overlap that will affect contractility
(Elastic rubber band with little cross-bridge cycling)
(Length-Tension (Frank-Starling) Relationship)
1 –> 2?
-Contraction - “Active” isometric force produced by cross-bridge cycling
-Chamber pressures increase with contractility
(Cross-Bridge cycling + [Ca2+] increases pressure)
(Length-Tension (Frank-Starling) Relationship)
2 –> 3?
-Active force overcomes “afterload”, allowing muscle shortening with continued cross-bridge cycling and contractility
-For the Heart, ventricular pressure exceeds aortic pressure (afterload), allowing ejection
(Does not reach max because aortic valve opens)
(Length-Tension (Frank-Starling) Relationship)
3 –> 4?
-Active force ends (relaxation) and only “passive” force on shortened muscle remains
(Relaxation = only passive forces)
