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Respiratory Physiology > Quiz 3 Pulmonary & Bronchial Circulations > Flashcards

Quiz 3 Pulmonary & Bronchial Circulations Flashcards

1
Q

How does pulmonary blood pressure and flow compare to the systemic system?

A

Pulmonary circulation= low pressure, high flow (because resistance is 1/10th of systemic circulation)

Systemic circulation= high pressure, low flow

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2
Q

What is different about the Pulmonary Artery compared to the Aorta?

A

Pulmonary artery is 1/3 thickness of aorta and is very compliant

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3
Q

What is the pressure in the Right Atrium?

A

1 to 10

Mean 5

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4
Q

What is the pressure in the Right Ventricle?

A

15-30/0-8

Mean 25/5

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5
Q

What is the pressure in the Pulmonary Artery?

A

15-30/ 5-15

Mean = 15

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6
Q

What is the pressure in the Pulmonary Capillaries (PAWP)?

A

5-15

Mean 10

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7
Q

What is the pressure in the Left Atrium?

A

4-12

Mean 8

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8
Q

What is the pressure in the Left Ventricle?

A

90-140/ 4-12

Mean 130/8

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9
Q

What is the pressure in the Aorta?

A

120/80

Mean 90

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10
Q

Will high positive pressure during lung expansion collapse the alveolar vessels? What about extra-alveolar vessels?

A

Yes, but not the extra-alveolar vessels

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11
Q

What is the difference between alveolar vessels and extra-alveolar vessels?

A

Alveolar vessels= small vessels on the acini involved in gas exchange (alveolarcapillary unit)

Extra-alveolar vessels= larger vessels that deliver blood to-and-from the respiratory units
-also contain Bronchial Vessels

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12
Q

What are Bronchial Vessels and and much of CO goes into them?

A

Vessels that supply systemic oxygenated blood to respiratory structures themselves.
1-2% of the cardiac output
Empties into the left atrium (natural physiologic shunt)

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13
Q

How much do the alveolar capillary walls contribute to resistance in the pulmonary system?

A

40 %

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14
Q

How much do the alveolar arterioles contribute to the resistence in the pulmonary system?

A

50 %

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15
Q

How much of the alveolar surface area is covered by capillary bed?

A

70 - 80 %

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16
Q

What is the normal capillary volume at rest in the pulmonary system?

What is the max volume?

A

70 mL (1 mL/kg)

Max 200mL during exercise

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17
Q

What is the total capillary network blood volume equal to?

answer not numeric

A

RV stroke volume

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18
Q

How long do RBCs remain in network and how long does it take for gas exchange equilibrium?

A

Remain in network for .75 sec (1 cardiac cycle), but only takes 0.25 seconds to exchange!

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19
Q

How much weight is blood in the lung?

A

40 - 50 % blood by weight, more than any other organ!

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20
Q

How much can the pulmonary vasculature alter its volume and what does it act as for the LA?

A

Acts as a capacitance reservoir for the LA.

Can alter from 50% to 200% of resting volume

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21
Q

Total blood volume in pulmonary circulation (PA to LA)?

A

500 mL

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22
Q

What is recruitment and distention in the pulmonary system?

A

2 mechanisms to passively regulate increases in BF due to increased CO

Recruitment- the opening of previously closed vessels to increase the capillary volume

Distention- widening of capillary beds to accommodate increased blood/pressure. Seen in disease states LV failure/Mitral regurg

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23
Q

When CO is increased and raises pulmonary vascular pressures, what happens to pulmonary vascular resistance?

A

It decreases the pulmonary vascular resistance because of recruitment (expands to make a larger surface area)

*Recruitment is a Chief mechanism for reduction in PVR

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24
Q

How happens to pulmonary blood flow on inspiration in terms of pleural/thorax pressure and ventricular ejection?

A

Pleural pressure is more negative= higher thoracic pressure

  • venous return is increased, so RV SV increased
  • LV SV decreased d/t increased pressure gradient
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25
Q

How happens to pulmonary blood flow on expiration in terms of pleural/ thoracic pressure and ventricular ejection?

A

Pleural pressure is less negative= lower/more positive thoracic pressure

  • venous blood return decreased, so RV SV decreased
  • LV SV increased r/t reduction in the pressure gradient
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26
Q

True or False: Pulmonary vascular resistance increases with both higher and lower lung volumes

A

True

27
Q

Bronchial blood circulation returns to right atrium via WHAT?

A

Azygos vein

28
Q

True or False: Approximately 50 % of the bronchial blood exits lung by small anastomoses with pulmonary veins contributing to normal venous admixture?

A

True

29
Q

How fast does the pulmonary lymphatic system drain fluid out?

A

20 mL /hr

30
Q

Is the interstitium kept at a negative or positive pressure?

A

Slightly negative (-5) for lymphatics to drain

31
Q

What are the measurement techniques of Fick’s Principle?

not super important..

A
  • way to determine CO by using bloodflow through lungs/min
  • oxygen consumption/min=oxygen uptake by blood in lungs/min
  • Measurement of arterial and mixed venous blood and determination of O2 consumption.
  • CO = O2 consumption (VO2)/ arteriovenous (O2) difference.
32
Q

What is the minimum VO2 at rest?

A

300 ml/min

33
Q

What effect does exercising have on blood flow to the lungs?

A

increases flow 4 to 7 fold and turns entire lung into zone 3.

34
Q

What is hydrostatic pressure and what are the Zero Reference Points?

A

Hydrostatic pressure is the pressure effect gravity has on a column of fluid.

Zero Reference Points:
Right Atrium level and middle of the lung

35
Q

How does gravity affect the differenct zones in the lung?

A
  • Lung bases receive more of the RV ejection fraction than do the apex.
  • Hydrostatic pressure causes distention and recruitment of pulmonary capillaries in base of lung (when standing)
  • Gravity pulls down on the lung causing alveoli at apex to be more open compared to the bases
  • Ventilation and perfusion are affected by gravity
36
Q

Which lung zone is optimum for gas exchange and why?

A

Zone 3 because that area has the best blood flow d/t gravity.
P artery> P vein> P alveoli

37
Q

Is a low or high V/Q mismatch better for gas exchange?

A

A low V/Q mismatch means that ventilation and perfusion are nearly equal

38
Q

which zone of the lungs has intermittent gas exchange?

A

Zone 2

P artery> P alveoli> P vein

39
Q

Which zone has no gas exchange and why?

A

Zone 1 because PA>Pa>Pv

Higher alveolar pressure will collapse the pulmonary capillaries

40
Q

What are some factors that create more zone 1 conditions?

A
  • Decreased Pulm Artery pressure (shock, sepsis)
  • Increased alveolar pressure (PEEP)
  • Occlusion of vessels (PE)
41
Q

What are some factors that decrease zone 1 conditions?

A
  • Increased Pulm Artery pressure (infusion of blood or fluid)
  • Reduced hydrostatic effect (change pt position, standing to supine)
42
Q

What can increase and decrease PVR?

A

Increase PVR - Hypoxia

Decrease PVR - Increased Cardiac Output

43
Q

How does active regulation of blood flow throughout the pulmonary system occur?

A
  • by altering vascular smooth muscle tone in arterioles and capillaries.
  • sympathetic outflow causes vasoconstriction
  • most active regulation of pulm vessels is mediated by local metabolic influences*
44
Q

What are 4 of the many vasoconstrictors?

A
  • Reduced PAO2
  • Increased PCO2
  • Histamine
  • Thromboxane A2: local vasoconstrictor produced during acute lung tissue damage
45
Q

What are 3 of the many vasodilators?

A
  • Increased PAO2
  • Nitric Oxide: epithelial vasodilator
  • Prostacyclin: potent vasodilator
46
Q

What is unique about Nitric Oxide?

A
  • Produced right in area where it works (strictly localized)
  • smooth muscle relaxation through synthesis of cyclic GMP
  • is very toxic in high concentrations
  • binds to heme 200,000 times > oxygen
47
Q

What happens if there is a global reduction in alveolar oxygen tension?

A

Total PVR increase by constriction of arterioles and small arteries

48
Q

How is the pulmonary vasculature opposite of the systemic vasulature when it becomes hypoxic?

A

Hypoxia in alveoli produces hypoxic pulmonary vasoconstriction (HPV), so blood is shifted to better oxygenated alveoli

Opposite reaction of hypoxia in the systemic vasculature which causes vasodilation

49
Q

Why is hypoxic pulmonary vasoconstriction (HPV) important for balancing the V/Q ratio?

A

It will help shunt blood to better ventilated areas of the lungs. (does not affect overall PVR if <20% involved)

50
Q

What is pulmonary Hypertension?

A

Increased resistance to blood flow in the lung

High PVR/ elevated PA pressures

51
Q

What causes high PVR and elevated pulmonary artery pressures (Pulmonary Hypertension)?

A
  • generalized alveolar hypoxia
  • Low PO2, High PCO2
  • Hypoventilation
  • Pain
  • Histamine release
52
Q

Which side of the heart does pulmonary HTN cause increased work and why?

A

Right Ventricle

  • RV hypertrophy
  • Tricuspid regurg
  • R heart failure (cor pulmonale)
53
Q

What is the only effective treatment for pulmonary htn?

A

lung transplant

54
Q

Which portion of the lung tends to be better ventilated?

A

the lower portion of the lung. (upper lung is open 60% vs lower lung open 40% at FRC. With inspiration, both will open to 100% but the lower portion actually opens more than the upper lung can.

55
Q

What is a normal A-a gradient? What does an elevated A-a gradient indicate?

A

Normal: 10-15mm Hg

if larger Alveolar to arterial gradient, there is some degree of shunting (disease process)

56
Q

What is a R–>L heart shunt?

A

Shunt = Perfused but not ventilated

  • some blood not being oxygenated/ participating in gas exchange
  • venous admixture = BF equivalent of wasted ventilation
57
Q

What is a L–>R heart shunt?

A

Portion of CO return to right heart without flowing to body (does not affect systemic arterial O2 tension)

58
Q

What is the pressure gradient on the systemic system due to gravity?

A

0.74 mm Hg/cm

59
Q

Is the blood pressure higher or lower in the feet when a person is in the supine position?

A

Higher pressures in the feet.

60
Q

What does the right ventricle EF of blood equal?

A

LV Cardiac Output

61
Q

When is total pulmonary vascular resistance highest?

What happens to alveolar and extra-alveolar vessels?

A

At either volume extreme (high lung volumes and low lung volumes):

Max inspiration: alveolar resistance= high because alveoli pressure increases and increases pressure on alveolar blood vessels + they constrict (and extra-alveolar dilate)

Max expiration: extra-alveolar resistance = high because pleural pressure is less negative and extra-alveolar blood vessels are compressed (alveolar?)

62
Q

When is total pulmonary vascular resistance lowest?

A

When lung volume close to FRC (at passive expiration)

FYI Total vessel resistance= alveolar+extra alveolar resistance, but the alveolar capillaries contribute more

63
Q

How does mechanical ventilation affect alveoli and pulmonary vascular resistance?

A
  • Positive pressure increases alveolar pressure= increase in resistance to blood flow
  • Increases amount of Zone 2 lung volume: those alveoli will distend greater and not allow flow through
  • can decrease CO (by decreasing venous return) or increase V/Q imbalance

Respiratory Physiology (11 decks)

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