Pulmonary Blood flow

Question 1

Alveolar capillaries

-Are involved in the exchange of?

Answer 1

• 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

Question 2

Extra-alveolar capillaries

-Arise from?

Answer 2

The left ventricle

Question 3

Extra-alveolar capillaries-function?

Answer 3

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

Question 4

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

Answer 4

• Reduces the PaO2 of the arterial blood by a few mmHg

- Increases the PaCO2 to a small degree

Question 5

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

Answer 5

Pulmonary veins

Question 6

Alveolar capillary

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

Answer 6

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

Question 7

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

Answer 7

High PaO2, Low PaCO2

Question 8

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

Answer 8

Low PaO2, High PaCO2

Question 9

Pulmonary vascular resistance

-Important reminder- BP=?

Answer 9

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

Question 10

Normal pulmonary blood pressure?

Normal cardiac output?

Answer 10

• Normal PBP is 25/15 (MAP = 18)

- Cardiac output is 4 L/min

Question 11

Systemic side

• Normal systemic mean arterial pressure?
• Normal cardiac output?

Answer 11

• Systemic MAP = 90 mmHg

- Cardiac output = 4 L/min

Question 12

Ratio of PVR to systemic?

Answer 12

1/4

Question 13

Pulmonary vascular resistance is determined by?

Answer 13

• 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

Question 14

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

Answer 14

Increase blood flow to areas of the lung with good oxygenation

Question 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?

Answer 15

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

Question 16

PVR also depends on lung volume

-What happens to resistance at low or very high lung volumes?

Answer 16

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

Question 17

PVR-normal value?

Answer 17

LOW

Question 18

PVR-major constrictor?

Answer 18

Hypoxia

Question 19

PVR-Change with exercise?

Answer 19

Decreases

Question 20

PVR-Major control?

Answer 20

Local

Question 21

Systemic resistance-normal value?

Answer 21

Moderate

Question 22

Systemic resistance-major constrictor?

Answer 22

Sympathetics

Question 23

Systemic resistance-change with exercise?

Answer 23

Decrease

Question 24

Systemic resistance-Major control?

Answer 24

ANS

Question 25

Regional blood flow in the lungs?

Answer 25

- 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

Question 26

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

Answer 26

- 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

Question 27

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

Answer 27

- 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'

Question 28

Regional blood flow in the lungs | -Zone 3?

Answer 28

- 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

Question 29

Regional blood flow (short and sweet) | -Apex?

Answer 29

High alveolar pressure, low blood pressure: little blood

Question 30

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

Answer 30

Normal pressures on both sides: Normal blood

Question 31

Regional blood flow (short and sweet) | -Base?

Answer 31

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

Question 32

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

Answer 32

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

Question 33

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

Answer 33

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

Question 34

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

Answer 34

lalaedsnfd

Question 35

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

Answer 35

The lymphatics! (filter out fluid)

Question 36

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

Answer 36

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

Question 37

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

Answer 37

ACE (angiotensin converting enzyme) inactivates bradykinin

Question 38

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

Answer 38

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

Question 39

Alveolar Capillaries | -Arise from?

Answer 39

the right ventricle