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_Physiology Exam 4 > 3/21: Pulmonary Circulation II > Flashcards

3/21: Pulmonary Circulation II Flashcards

1
Q

What do hydrostatic pressure gradients alter?

A

Regional pulmonary flow

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2
Q

What happens to hydrostatic pressure gradients when upright?

A

there is a 23-mmHg difference in pulmonary arterial pressure
from zone 1 (apex) to zone 3 (base) due to gravity

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3
Q

What 3 zones is the lung divided into?

A

Zone 1: most superior (apex)
Zone 2: middle
Zone 3: inferior (base of lung)

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4
Q

Describe zone 3

A

Highest hydrostatic pressure and highest blood flow per alveolus

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5
Q

Describe zone 1

A

lowest hydrostatic pressure and lowest blood flow

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6
Q

What does exercise do to hydrostatic pressure gradients?

A

exercise increases blood flow to all zones of the lung, though
zone 3 (base) sill receives the most blood flow

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7
Q

Where do pulmonary capillaries in the zones of the lung experience force from fluids?

A

Inside (Pc) and outside the vessel (PALV)

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8
Q

What is Pa?

A

Hydrostatic pressure of the blood inside the capilaries

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9
Q

What does hydrostatic pressure of the blood inside the capillaries favor?

A

Filtration (and keeps the vessels open)

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10
Q

Where is Pa greater?

A

In zone 3 of the lungs compared to zone 2 (Due to gravity)

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11
Q

What is PALV/PA ?

A

Alveolar air pressure

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12
Q

What does alveolar air pressure impact?

A

Tissue pressure outside the capillary

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13
Q

What does alveolar air pressure oppose?

A

Filtration and favors vessel collapse

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14
Q

What does PA alter?

A

The capillaries and smallest of the arterioles and venules (alveolar vessels)

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15
Q

Describe the arterial and alveolar pressure in zone 1?

A

Pa is lower than PA
- capillaries are compressed

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16
Q

What happens if Pa drops (hemorrhage) or PA increases (positive pressure breathing)?

A

A greater portion of the lung is converted to zone 1

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17
Q

Describe Pa and PA in zone 2

A

Higher Pa (due to gravity) means that Pa is higher than PA during systole
During diastole Pa will drop lower than PA
Thus, blood flow is intermittent

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18
Q

Describe Pa and PA in zone 3

A

Higher Pa (due to gravity)
Region of continous blood flow because Pa remains higher than PA during both systole and diastole

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19
Q

What zones do majority of healthy lungs have?

A

Zone 2
Zone 3
*no zone 1

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20
Q

What zones does exercise convert?

A

Zone 2 to zone 3 blood flow

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21
Q

When you are supine, what zone does this involve?

A

lungs have mostly Zone 2 (gravity)
**Diseased lung patient → should not be supine in dental chair because it further reduces their gas

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22
Q

What is ventilation (V)/ perfusion (Q) match?

A

Index of the match between air flow (alveolar ventilation, V) and pulmonary blood flow (perfusion, Q)

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23
Q

What is normal whole lung V/Q?

A

0.8 which means there is more blood flow than air flow

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24
Q

In a normal individual, which zone has a higher V/Q than the rest of the lung?

A

Apex (zone 1)
- meaning they will get more ventilation than perfusion

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25
Q

As one moves from zone 1 to zone 3, there is a ______________ in ventilation than blood flow

A

Slower increase

26
Q

What do shallow breaths in upright position do to V/Q?

A

V/Q mismatch because air flows to upper lobes and blood to lower lobes

27
Q

Describe the ventilation of zone 1

A

Less ventilation

28
Q

Describe intrapleural pressure in zone 1

A

More negative

29
Q

Describe transmural pressure gradient in zone 1?

A

Greater

30
Q

Describe alveoli in zone 1

A

Larger alveoli, less compliant

31
Q

Describe ventilation in zone 3

A

More ventilation

32
Q

Describe intrapleural pressure in zone 3

A

Less negative

33
Q

Describe pressure gradient in zone 3

A

Small transmural pressure gradient

34
Q

Describe the alveoli in zone 3

A

Smaller, more compliant

35
Q

What is the overall takeaway regarding ventilation in the zones?

A

Alveoli at the base of the lungs receives more ventilation than those in the apex

36
Q

Describe the blood flow in perfusion in zone 1

A

Less blood flow

37
Q

Describe the intravascular pressure in perfusion in zone 1

A

Lower intravascular pressure

38
Q

Describe the distension in perfusion in zone 1?

A

Less recruitment, distension

39
Q

Describe the resistance in perfusion of zone 1

A

Higher resistance

40
Q

Describe the blood flow in resistance in zone 3

A

greater blood flow

41
Q

Describe the vascular pressure in perfusion in zone 3

A

greater vascular pressure

42
Q

Describe distension in perfusion in zone 3

A

more recruitment, distension

43
Q

Describe resistance in perfusion in zone 3

A

Lower resistance

44
Q

What is the overall takeaway regarding perfusion in the zones?

A

the pulmonary capillaries at the base of the lungs receive more
blood flow than those in the apex

45
Q

What kind of response is V/Q mismatch?

A

Local negative feedback response

46
Q

What is the response of V/Q mismatch?

A

Respiratory and circulatory systems are working to deliver air and blood to the same portions of the respiratory membrane

47
Q

What happens to V/Q and O2/CO2 if ventilation is limited?

A

V/Q is low
O2 is low and CO2 is high
Smooth muscles in the vaso vasoconstrict

48
Q

What happens to V/Q and O2/CO2 if perfusion is limited?

A

V/Q is high
O2 is high and CO2 is low
Smooth muscles in the
bronchioles bronchoconstrict

49
Q

When must gas exchange occur?

A

During the time frame of blood transversing through pulmonary capillaries in 0.3-0.8 seconds

50
Q

What is fluid filtration determined by?

A

Hydrostatic fluid forces and capillary and interstitial colloid

51
Q

How is fluid filtration determined by?

A

As dictated by starling’s forces
- fluid filtration is determined by hydrostatic fluid forces and capilalry and interstitial colloid

52
Q

Describe hydrostatic pressure during pulmonary capillary exchange

A

Hydrostatic pressures = fluid
▪ Capillary pressure (Pc)
▪ Interstitial fluid pressure (PIF)
* If PIF is negative = filtration pressure
* If PIF is positive = absorption pressure

53
Q

Describe osmotic pressure during pulmonary capillary exchange

A

Osmotic pressures = proteins
▪ Plasma colloid osmotic pressure 𝜋P
▪ Interstitial fluid colloid osmotic pressure 𝜋IF
* Value is about twice the amount in systemic tissues because
pulmonary capillaries are leaky to protein

54
Q

What us the overall effect of filtration?

A

overall effect is filtration (net pressure is +1 (29-28), favors
fluid movement out of pulmonary capillaries)

55
Q

Describe the filtration pressures

A

Total = 29 mmHg
o Capillary pressure (Pc) = 7 mmHg
o Interstitial fluid pressure
(PIF) = -8 (use absolute value)
- more negative than peripheral intersitium – GOOD since favors fluid filtration from alveoli, too
o Interstitial fluid colloid osmotic pressure 𝜋IF = 14 mmHg
- value is ~twice that in systemic tissues because pulmonary capillaries are leaky to protein

56
Q

Describe the absorption pressure

A

Total = 22 mmHg
o Plasma colloid osmotic pressure 𝜋P = 22 mmHg

57
Q

Where is there a slight continual flow of fluid and why?

A

Normal filtration forces are greater than the absorptive forces by +1 mmHg (29-28), so there is a slight continual flow of fluid from the pulmonary capillaries into interstitial spaces

58
Q

What is fluid that leaves the capillaries absorbed and returned by?

A

Lymphatic circulation and returned to the circulation

59
Q

Where does extra fluid that enters the alveoli moved into?

A

Extra fluid that renters the alveoli will be moved into the interstitial space due to the slight negative pressure and then picked up by lymphatic capillaries
This keeps the alveoli dry

60
Q

When in lymphatics is balance maintained?

A

In healthy respiratory/circulatory system

61
Q

What is disrupted balance during lymphatics?

A

pulmonary edema (large increases in net capillary filtration
▪ Can occur with left sided heart failure, mitral valve stenosis, and damage to pulmonary capillary membranes

_Physiology Exam 4 (8 decks)

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