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Flashcards in Pulmonary Blood flow Deck (39):
1

Alveolar capillaries
-Are involved in the exchange of?

-Alveolar capillaries are involved in the exchange of O2 and CO2 between blood and air
-Millions of alveolar capillaries make it so the alveoli are effectively a sheet of capillaries

2

Extra-alveolar capillaries
-Arise from?

The left ventricle

3

Extra-alveolar capillaries-function?

-Function as normal systemic capillaries
-Deliver O2 and CO2 to the tissue of the lungs
-Provide nutrients/remove waste from lung tissue

4

Extra-alveolar capillaries-Return to the heart in the pulmonary veins (venous admixture)
-Effect on PaO2 of the arterial blood? PaCO2?

-Reduces the PaO2 of the arterial blood by a few mmHg
-Increases the PaCO2 to a small degree

5

Alveolar and Extra-alveolar capillaries return to the heart via?

Pulmonary veins

6

Alveolar capillary
-PaO2?
-PaCO2?
-How do these levels compare to those extra-alveolar capillaries?

-Low PaO2
-High PaCO2
-These levels are switched in extra-alveolar capillaries

7

After the alveolar capillaries return via the pulmonary vein, what are the blood gases?

High PaO2, Low PaCO2

8

After the extra-alveolar capillaries return via the pulmonary vein, what are the blood gases?

Low PaO2, High PaCO2

9

Pulmonary vascular resistance
-Important reminder- BP=?

BP = CO x TPR
This equation holds true in the lung as well, but substitute in pulmonary vascular resistance (PVR) for TPR
PBP = CO x PVR

10

Normal pulmonary blood pressure?
Normal cardiac output?

-Normal PBP is 25/15 (MAP = 18)
-Cardiac output is 4 L/min

11

Systemic side
-Normal systemic mean arterial pressure?
-Normal cardiac output?

-Systemic MAP = 90 mmHg
-Cardiac output = 4 L/min

12

Ratio of PVR to systemic?

1/4

13

Pulmonary vascular resistance is determined by?

-High number of capillaries
-How many capillaries are open at any given moment in time (it is perfectly normal not to be using all your lungs at rest)
-Much less sympathetic tone/vasoconstricting forces
-Lung volume

14

What is the major role of the vasoconstriction produced by hypoxia?

Increase blood flow to areas of the lung with good oxygenation

15

Pulmonary Vascular Resistance
-How many capillaries are open at any given moment in time (it is perfectly normal not to be using all your lungs at rest)
-How does exercise affect PVR?

During exercise, PVR drops as more pulmonary capillaries open up to accommodate the increased cardiac output

16

PVR also depends on lung volume
-What happens to resistance at low or very high lung volumes?

The PVR increases a little because the stretch of the tissue compresses the capillaries

17

PVR-normal value?

LOW

18

PVR-major constrictor?

Hypoxia

19

PVR-Change with exercise?

Decreases

20

PVR-Major control?

Local

21

Systemic resistance-normal value?

Moderate

22

Systemic resistance-major constrictor?

Sympathetics

23

Systemic resistance-change with exercise?

Decrease

24

Systemic resistance-Major control?

ANS

25

Regional blood flow in the lungs?

-As we already know, gravity works on the blood in our bodies- when we stand, the hydrostatic pressure in our legs is increased compared to the level of the heart or in the brain
-The same is true in the lungs

26

Regional blood flow in the lungs
-Zone 1/apex?

-PA > Pa > PV
-At the apex of the lung, the blood pressure is reduced because it is slightly above the level of the heart
-However, the alveoli are somewhat expanded (take as fact for right now)
-The blood flow is less

27

Regional blood flow in the lungs
-Zone 2/pulmonary artery/vein?

-Pa > PA > PV
-In the middle regions of the lung, the blood pressure is a little higher because we are at the level of the heart
-The alveoli are average size (take as fact right now)
-The blood flow is "normal'

28

Regional blood flow in the lungs
-Zone 3?

-Pa > PV > PA
-At the base of the lung, the blood pressure is high because we are below the level of the heart
-The alveoli are smaller (take as fact right now)
-The blood flow is greater than in other regions of the lung

29

Regional blood flow (short and sweet)
-Apex?

High alveolar pressure, low blood pressure: little blood

30

Regional blood flow (short and sweet)
-Middle regions?

Normal pressures on both sides: Normal blood

31

Regional blood flow (short and sweet)
-Base?

Relatively low alveolar pressure, relatively high blood pressure: lots of blood

32

Chemical Modulators of pulmonary blood flow
-Nitric oxide
-produced by?
-Causes what to happen?
-Significant role in?

-Produced by the endothelium
-Causes smooth muscle relaxation and vasodilation
-Significant role in normal pulmonary blood flow

33

Endothelin 1
-Produced in?
-Causes what to happen?
-Seems to have a role under what type of conditions?

-Produced in the lungs
-Causes vasoconstriction
-Seems to be a player under pathologic (not normal) conditions

34

Thromboxane A2
-Treat it the same as endothelin 1-can be found under certain pathologic conditions

lalaedsnfd

35

Describe the mechanisms by which the alveoli are kept "dry"

The lymphatics! (filter out fluid)

36

Describe the role of the lung in the production of angiotensin 2

Has angiotensin converting enzyme (ACE)
-converts angiotensin 1 to angiotensin 2

37

Describe the role of the lung in the metabolism of bradykinin?

ACE (angiotensin converting enzyme) inactivates bradykinin

38

Describe the role of the lung in the production/metabolism of arachidonic acid metabolites

Leukotrienes and prostaglandins are produced by immune system activation in the lungs
Prostaglandin E2, F2a, and leukotrienes are almost completely removed from the circulation in the lungs

39

Alveolar Capillaries
-Arise from?

the right ventricle