Cardiac Lecture 2 Flashcards
What is Reynold’s number?
Theoretical number to calculate likelihood of turbulent flow
What Reynold’s number is turbulent flow likely?
> 2000
If blood vessel diameter increases, will turbulence increase or decrease?
Increase turbulence
If blood velocity increases, will turbulence increase or decrease?
increase turbulence
If blood density increases, will turbulence increase or decrease?
increase turbulence
If blood viscosity increases, will turbulence increase or decrease?
decrease turbulence
Which blood vessels are most prone to turbulent flow?
Aorta and large arteries
Flow meter assesses blood flow by using an electromagnetic probe to measure the magnetic field produced by ______
iron in heme
Phase 1 of the cardiac cycle occurs during
ventricular filling/diastole
During phase 1, the mitral valve is ______ and the aortic valve is _______
mitral open, aortic closed
During phase 2, the mitral valve is ______ and the aortic valve is _______
mitral closed, aortic closed
During phase 3, the mitral valve is ______ and the aortic valve is _______
mitral closed, aortic open
During phase 4, the mitral valve is ______ and the aortic valve is _______
mitral closed, aortic closed
What do we call the amount of blood remaining at the end of systole, and how much is it?
End-systolic volume, 50mL
What do we call the amount of blood in the ventricle at the end of filling, and how much is it?
End-diastolic volume, 120mL
Normal stroke volume is ____ mL
70mL
Atrial contraction provides what amount of end-diastolic volume, ____mL? (in healthy person)
10mL
In heart failure, atrial kick provides ______ % of end-diastolic volume
> 25%
Stroke volume = ______ - _________
stroke volume = end diastolic volume - end systolic volume
At the beginning of phase 1, pressure in the left atria is greater or less than left ventricle?
LAP > LVP; that’s why the mitral valve opens
Diastole is phase _____ of the cardiac cycle
1
The mitral valve is also called the _______ valve
Bicuspid valve
When LV pressure is > LA pressure the ______ valve will ________
mitral valve/bicuspid valve, close
Interventricular volume does not change in which phases?
2 and 4
phase 2 is also called ______ _______
isovolumetric contraction
phase 4 is also called ______ _______
isovolumetric relaxation
In phase 2 the ventricle is ______
beginning to contract
Phase 2 ends when ______
Aortic valve opens
Phase 3 is also the _____ _______ ______
period of ejection
Phase 3 begins when ______
aortic valve opens
Phase 3 ends when _____
aortic valve closes
systemic pressure is > LV pressure
Phase 4 begins when ______
aortic valve closes
relaxation occurs without volume change
Phase 4 ends when _____
mitral valve opens
LA pressure is > LV pressure
The diastolic blood pressure number is the pressure when _______
aortic valve opens
For our class, diastole starts when ________
aortic valve closes
(end of phase 3, start of phase 4)
For our class, systole starts at ________
end of phase 1/start of phase 2, at end-diastolic volume
The vast majority of ventricular filling occurs ______
early, first 1/3 of filling
If the mitral (bicuspid) valve is stenotic, how will it affect LV filling?
filling will occur slower due to impedance of blood flow from LA to LV
With mitral stenosis, you want the heart rate to be higher or lower?
Lower. Because slower LV filling, lower HR will give more time to fill
1st heart sound is when ______
A-V valves close; tricuspid and mitral(bicuspid)
2nd heart sound is when ______
aortic and pulmonic valve closes
Aortic blood pressure is lowest at ____
end of phase 2
Normal mean systemic filling pressure (Psf) is
+7 mmHg
ΔP equals
Avg cv pressure - RA pressure
normal ΔP = (7-0)=7
reduction in RVR would _______ (increase/decrease) venous return and CO
increase
increase in RVR would _______ (increase/decrease) venous return and CO
decrease
Something that impedes blood from returning to the heart would _____ (increase/decrease) RVR
increase
Low RVR would cause the slope on the venous return graph to be _______
steep
High RVR would cause the slope on the venous return graph to be _______
less steep
2 main factors that contribute to mean systemic filing pressure are
blood volume and venous tone
What are the 3 factors that augment cardiac output when filling pressures increase
- Frank Starling mechanism (cross bridge alignment, healthy heart under stretched at rest)
- Direct atrial stretch: property of conduction system of the heart. If atria stretched, causes HR to increase by 10-15%
- Bainbridge reflex: external reflex from heart to CNS and back to heart (through vagus nerve) to accommodate higher filling pressure. increases HR by 40-50%
Direct atrial stretch does or does not rely on nerve activity to increase HR?
doesn’t rely on nerve activity
Both afferent and efferent parts of the Bainbridge reflex are carried by the _______
vagus nerve
heart —> vagus nerve –> brain stem –> inc. sympathetic output and decrease sympathetic output by vagus nerve
