2 CVS - The Heart as a Pump Flashcards
What is systole?
Contraction and ejection of blood from ventricles
What is diastole?
Relaxation of filling of ventricles
What is the stroke volume?
The amount of blood pumped per beat. 70ml per beat
An action potential causes a rise in intracellular ….?
Calcium
What heart valve is on the right?
Tricuspid
What heart valve is on the left?
Mitral
What controls the opening and closing of valves?
The differential blood pressure on either side of it
When atrial pressure is higher than ventricle pressure, what will happen?
the mitral and tricuspid valves will open?
What do the cusps of the mitral and tricuspid valves attach to?
Attach to papillary muscles via chordae tendineae
What are the seven phases of the cardiac cycle?
1 Atrial Contraction 2 Isovolumetric Contraction 3 Rapid ejection 4 Reduced ejection 5 Isovolumetric relaxation 6 Rapid filling 7 Reduced filling
What phases are involved in systole?
2-4
What effect does heart rate on systole and diastole?
Systole remains constant from beat to beat, the length of diastole varies with heart rate
How long is systole?
0.35 seconds
What is the A wave?
the rise in atrial pressure due to atrial systole
How is the majority of ventricle filling achieved?
Passive diffusion
What does the P wave on an ECG signify?
Onset of atrial depolarisation?
What is on the X and Y axis of a wiggers diagram?
X axis is used to plot the time
Y axis is used to plot Aortic, Atrial and Ventricular pressure and ventricular volume and an ECG
When does the mitral valve close?
As the intraventricular pressure exceeds the atrial pressure
What happens to the ventricular volume during isovolumetric contraction?
No change in volume as all the valves are closed
What happens to the ventricular pressure during isovolumetric contraction?
there is a rapid rise in ventricular pressure as it contracts
What is responsible for the first hear sound? S1
Closure of the mitral and tricuspid valves, results in the first heart sound
When does ventricular ejection begin?
When the intraventricular pressure exceeds the pressure within the aorta?
What noise is the opening of the aortic valve responsible for?
None, ya dummy
What is the X descent
During rapid ejection, the Atrial pressure is initially decreased as the atrial base is pulled downwards as the ventricle contracts. This is called the “X descent”
What leads to a reduced rate of ejection?
Repolarization of the ventricles
What is the V wave?
Atrial pressure gradually rises due to the continuous venous return. V wave = Venous return
What is the dicrotic notch?
The graph of aortic pressure throughout the cardiac cycle displays a small dip which coincides with the aortic valve closure.
What causes the aortic valve to close?
When the intra-ventricular pressure falls below the aortic pressure, there is a brief back-flow of blood which causes the aortic valve to close
Closure of the aortic and pulmonary valves results in which heart sound?
S2
What is the Y descent?
Fall in atrial pressure, that occurs after the opening of the mitral valve
Sometimes there is a third heart sound, S3, what is the cause of this?
Ventricular filling
At rest how full are the ventricles?
90%
By the end of what phase can you calculate the EDV?
Atrial Contraction
What are the two main causes of abnormal valve function?
Stenosis and regurgitation
In simple terms what happens in valve stenosis?
The valve does’t open enough leading to obstruction to blood flow when the valve is open
What is regurgitation?
The valve doesn’t open all the way, leading to back leakage when the the valve should be closed
What are the causes of aortic valve stenosis?
Degenerative, congenital, chronic rheumatic fever
What are the complications of aortic valve stenosis?
LV hypertrophy, syncope, angina, Microangipathic haemolytic anaemia
What is microangiopathic haemolytic anaemia?
Loss of red blood cells through destruction, shear stress
What happens to systolic and diastolic pressure in aortic valve regurgitation?
Systolic pressure increases, diastolic pressure decreases
What is the main cause of mitral valve stenosis?
Rheumatic fever
