Flashcards in Heart as a Pump Deck (29)
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1
what is cardiac ouptut
volume of blood pump per min (5 L/min at rest)
2
equation for cardiac output
CO = HR x SV
3
what is stroke volume
amount of blood pump per beat
4
what controls heart rate
set by SA node
affected by autonomic NS
5
what affects stroke volume (3 things)
1) preload (venous return)
2) afterload (resistance to flow - aortic pressure)
3) strength of contraction
6
For LV what is preload ~ to?
end diastolic volume
7
factors that affect preload
1) blood volume
2) filling pressure and time (HR)
3) resistance to filling
- RA pressure
- AV stensosis
- ventricular compliance
8
Graph of EDPVR
what does graph mean
incr LV volume, incr LV pressure
9
Graph of EDPVR
what does slope mean
inverse of ventricular compliance
steeper slope = decr compliance b/c harder for ventricle to fill (hypertrophy)
10
how does hypertrophy affect EDPVR?
how does dilation affect EDPVR?
hypertrophy = steep slope = decr compliant
dilation = shallow slope = very compliant
11
for LV what is afterload ~ to?
aortic pressure
12
factors affecting afterload
1) aortic pressure
2) wall stress so wall thickness and radius (T= dP * R / u(thickness))
3) aortic stenosis
13
what is inotropy
contractility - force of contraction independent of fiber length
describes systolic fxn of heart
14
what is the biggest factor affecting inotropy
sympathetic tone
15
what is shown on EDPVR
P-V relationship during filling of heart BEFORE CONTRACTION
16
what does EDPVR slope mean
passive elastic properties of heart
slope = inverse of compliance
steeper = less complaint
17
EDPVR represents the ___ on the left ventricle
PRELOAD
18
what is shown on systolic pressure-volume relationship
P-V relationship at PEAK OF ISOMETRIC CONTRACTION
19
compare slopes of EDPVR vs. systolic PV relationship
Systolic P-V relationship is steeper (pressure incr a lot for small change in volume
20
what properties are included in systolic PV relationship
ACTIVE + PASSIVE
21
how do you create the Starling (ventricular function) curve
subtract SPVR from EDPVR
22
what does starling curve represent?
active tension
23
what are all the possible y axes for Starling curve
ventricular fxn on y-axis = tension, CO, stroke volume
24
what are all the possible x axes for Starling curve
preload on x-axis = length, pressure, or EDV
25
what does frank-starling law of heart describe (3 things)
1) heart ALWAYS ON ASCENDING LIMB OF STARLING CURVE
2) heart responds to incr in EDV with incr in force
3) what goes in heart must come out
26
what does a violation of frank starling law lead to?
HEART FAILURE
27
HOW DOES incr preload affect PV loop?
shift EDV to the right
more EDV, so heart contract with more force to ensure same end systolic volume
--> INCR STROKE VOLUME
28
How does incr afterload affect PV loop?
shift end systolic volume to the right and shift top pressure line up
incr aortic pressure = heart work harder to eject, less time
incr end systolic volume (can't empty)
--> DECR STROKE VOLUME
29
