L38 Hemodynamics

Question 1

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

Answer 1

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

Question 2

What does cardiac output depend upon?

Answer 2

CO = SV * HR

Question 3

___ determines oxygen delivery; ___ determines organ perfusion.

Answer 3

Cardiac output; blood pressure

Question 4

What is CO?

Answer 4

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

Question 5

What is SV?

Answer 5

How much blood the heart pumps per contraction

Question 6

What three factors determine SV?

Answer 6

Preload, afterload, contractility

Question 7

What is preload?

Answer 7

How much fluid is in the pump

Question 8

What is afterload?

Answer 8

How much resistance there is to pumping

Question 9

What is contractility?

Answer 9

How strong the pump is

Question 10

Describe the axes of the Frank Starling curve.

Answer 10

X-axis: preload

Y-axis: SV

Question 11

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

Answer 11

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

Question 12

When does the mitral valve shut?

Answer 12

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

Question 13

When does the atrial valve open?

Answer 13

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

Question 14

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

Answer 14

D; A

Question 15

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

Answer 15

B; C

Question 16

What is lucitropy?

Answer 16

The heart’s ability to relax and accept volume

Question 17

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

Answer 17

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

Question 18

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

Answer 18

Sarcomere length; stroke volume

Question 19

Compliance = ?

Answer 19

Change in volume/change in pressure

Question 20

When does the atrial valve close?

Answer 20

When left ventricular pressure is exceeded by aortic pressure

Question 21

How does the pressure volume loop shift up and down?

Answer 21

Increasing and decreasing afterload (arteriolar contraction)

Question 22

How is afterload measured?

Answer 22

Wall tension

Question 23

Increasing afterload ___ stroke volume.

Answer 23

Decreases (and vice versa)

Question 24

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

Answer 24

Contractility

Question 25

True or false - acutely changing afterload decreases SV and contractility.

Answer 25

False - it does not decrease contractility

Question 26

Where are the two main heart sounds heard?

Answer 26

S1 - closing of mitral valve (A)

S2 - closing of atrial valve (C)

Question 27

What is ejection fraction?

Answer 27

The % of blood being ejected with each contraction

Question 28

Ejection fraction = ?

Answer 28

(Full - empty)/Full * 100

Question 29

What is a normal ejection fraction?

Answer 29

~55%

Question 30

What 4 things increase CO?

Answer 30

1. Increasing HR (which also increases contractility)
2. Increasing preload
3. Decreasing afterload
4. Increasing contractility

Question 31

MAP = ?

Answer 31

2/3(DBP) + 1/3(SBP)

CO * SVR

Question 32

Resistance is proportional to…

Answer 32

…viscosity x length/radius^4

Question 33

Can we measure SVR? What about MAP?

Answer 33

We calculate SVR and measure MAP.