L38 Hemodynamics Flashcards

1
Q

What are the 4 important things upon which hemodynamic homeostasis depends?

A
  1. Preload
  2. Afterload
  3. Contractility
  4. Heart Rate
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2
Q

What does cardiac output depend upon?

A

CO = SV * HR

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3
Q

___ determines oxygen delivery; ___ determines organ perfusion.

A

Cardiac output; blood pressure

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4
Q

What is CO?

A

Measure of the volume of blood (and thus how much oxygen) can be delivered

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5
Q

What is SV?

A

How much blood the heart pumps per contraction

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6
Q

What three factors determine SV?

A

Preload, afterload, contractility

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7
Q

What is preload?

A

How much fluid is in the pump

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8
Q

What is afterload?

A

How much resistance there is to pumping

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9
Q

What is contractility?

A

How strong the pump is

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10
Q

Describe the axes of the Frank Starling curve.

A

X-axis: preload

Y-axis: SV

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11
Q

Describe the 4 points of the pressure volume loop, starting with A = bottom right corner.

A

A: MV closes
B: AV opens
C: AV closes
D: MV opens

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12
Q

When does the mitral valve shut?

A

When the pressure in the left ventricle is greater than the pressure in the left atrium

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13
Q

When does the atrial valve open?

A

When the pressure in the ventricle is greater than the pressure in the artery

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14
Q

Diastole (relaxation, filling) occurs from point ___ to ___.

A

D; A

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15
Q

Systole (contraction, emptying) occurs from point ___ to ___.

A

B; C

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16
Q

What is lucitropy?

A

The heart’s ability to relax and accept volume

17
Q

How does the pressure volume loop shift to the left or right?

A

Increasing or decreasing the preload or left ventricular end diastolic pressure;

Adding volume shifts to the right

Diuresis, nitrates, and blood loss shifts to the left

18
Q

The Frank Starling curve indicates that increased preload leads to increased ___ and therefore increased LV contraction and increased ___.

A

Sarcomere length; stroke volume

19
Q

Compliance = ?

A

Change in volume/change in pressure

20
Q

When does the atrial valve close?

A

When left ventricular pressure is exceeded by aortic pressure

21
Q

How does the pressure volume loop shift up and down?

A

Increasing and decreasing afterload (arteriolar contraction)

22
Q

How is afterload measured?

A

Wall tension

23
Q

Increasing afterload ___ stroke volume.

A

Decreases (and vice versa)

24
Q

The slope of the line at the top right of the pressure volume loop represents ___.

A

Contractility

25
True or false - acutely changing afterload decreases SV and contractility.
False - it does not decrease contractility
26
Where are the two main heart sounds heard?
S1 - closing of mitral valve (A) S2 - closing of atrial valve (C)
27
What is ejection fraction?
The % of blood being ejected with each contraction
28
Ejection fraction = ?
(Full - empty)/Full * 100
29
What is a normal ejection fraction?
~55%
30
What 4 things increase CO?
1. Increasing HR (which also increases contractility) 2. Increasing preload 3. Decreasing afterload 4. Increasing contractility
31
MAP = ?
2/3(DBP) + 1/3(SBP) CO * SVR
32
Resistance is proportional to...
...viscosity x length/radius^4
33
Can we measure SVR? What about MAP?
We calculate SVR and measure MAP.