Why is the pressure in the aorta decreasing prior to ventricular contraction?
peripheral runoff (blood is moving to the periphery, and no new blood is being added)
What is isovolumetric Contraction? What is isovolumetric relaxation?
- the ventricular volume is constant because all valves are closed, but the pressure is increasing
- the ventricular volume is constant because all valves are closed, but pressure is decreasing because the blood is gone
What must the ventricular pressure reach to open the SL valves?
the diastolic pressure of either the aortic pressure (left) or pulmonary pressure (right)
When do the SL valves close?
when the pressure in the ventricles is less than arterial P
What is the dicrotic notch?
occurs in the aortic pressure wave when the closing of the aortic valve occurs
What determines rate of peripheral run off?
resistance to blood flow
What causes the jugular “a” wave? “c” wave? “v” wave?
- since there is no valve between the atria and the great veins, the pressure is reflected backwards
- created by period of isovolumetric contraction in the ventricles (abrupt stop due to aortic valve opening)
- Blood is returning to the heart, but cannot enter Ventricles
What causes the first heart sound?
the closure of the AV valves because blood hits the closed valves
What causes the second heart sound?
the closure of the aortic and pulmonary valves (blood in the valves back flows, and hits closed valves)
Why does blood back flow when the aortic and pulmonary valves closes?
the pressure in the ventricles that was driving the blood forward is gone, and gravity pulls the blood down (and this causes them to hit the valve)
What causes the third heart sound?
blood rushing into the ventricles during its rapid filling phase (normal in children; rare in adults)
What causes the fourth heart sound?
when the atria contract, and a little more blood goes into the ventricles (normal in children, rare in adults)
What two things can cause a murmur?
- Blood is moving somewhere it shouldn’t
2. Blood is having a hard time moving somewhere it should
What causes systolic murmur?
- blood moving back into the atria by regurgitation (mitral)
- blood can’t get into the aorta/pulmonary artery due to stenosis
What causes a diastolic murmur?
- blood is moving back into the aorta or pulmonary after caused by regurgitation (aortic)
- blood can’t get into the ventricle due to stenosis
