The Heart Pump Flashcards
THe diastolic phase of the cardiac cycle begins with what?
opening of the atroventricular AV valves (mitral and tricuspid)
What happens to ventricular pressure and atrial pressure when the AV valves open?
blood flows rapidly into the ventricles, causing an increase in ventricular pressure and an initial drop in atrial pressure
Why does overall pressure gradually rise in both the ventricle and atrium during passive ventricular filling?
because blood is returning to the atrium from the veins as well
Near the end of ventricular diastole, contraction is initiated where?
in the atrium
What is the EKG equivalent of this atrial contraction?
P wave
WHen atrial pressure rises during atrial contraction an additional pulse of blood is pushed into the ventricles. This isn’t essentialf or adequate ventricular filling at rest, but it is important in times of increased heart rate. why?
because the passive filling time is shortened with elevated heart rate, so you need this extra push of blood to reach a necessary ventricular volume to maintain adequate stroke volume.
What maintins the arterial pressure during diastole?
the elastic recoil of the walls of the aorta and other large arteries.
Despite this, aortic pressure gradually falls during diastole. why?
during diastole the aorta continues to supply blood to the systemic vascular beds
What is the lowest aortic pressure called? When is it reached?
Diastolic pressure - reached at the end of diastole
What are the three things that proper ventricular filling depends on?
- filling pressure of blood returning to the heart
- ability of the AV valves to open fully
- Ability of the ventricular wall to expand passively with little resistance - high compliance
What triggers the beginning of systole/
the action potential passing thorugh the AV node to the ventricles
What EKG point corresponds with the depolarization and ventricular contraction?
the QRS complex
What happens when contraction of the ventricular muscle causes intraventricular pressure to rise above that in the atrium?
the AV valve slams shut
What heart sound corresponds to the AV valve closure?
S1 - this is the “lub”
What do you call the period between mitral valve closure and aortic valve opening?
isovolumetric contraction phase
What causes the aortic valve to passively open?
Contraction intensifies which means left ventricular pressure will exceed the pressure in the aorta - opening the aortic valve
What period starts when the aortic valve opens?
ventricular ejection
Do ventricular pressure and aortic pressure differ much during ventricular ejection? Why?
Not really…
ventricular pressure increases because contraction continues
aortic pressure increases because the blood is being pushed into it
they don’t differ much because the aortic valve orifice is large and presents very little resistance to flow
What is peak systolic pressure?
the maximum of aortic pressure that occurs during mid-systole
Ventricular relaxation and repolarization is represented by which peak on an EKG?
the T wave
After the strength of contraction wanes, aortic pressure falls because of what?
the blood is leaving the aorta and large arteries faster than is entering from the left ventricle
What happens when intraventricular pressure falls below aortic pressure when contraction is done?
the aortic valve leaflets close
What is the incisura or dicrotic notch in aortic pressure?
You get a slight bump back up in aortic pressure because the aortic valve leaflets close and the elastic recoil of the valve and the aorta cause a temporary rise in aortic pressure. it’s basically just a temporary rebound.
THe period between the aortic vavle closure and mitral valve opening is called what?
isovolumetric relaxation
