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556 - Physiology & Pathophysiology II > Exam 5 - Pulmonary Ventilation & Circulation > Flashcards

Exam 5 - Pulmonary Ventilation & Circulation Flashcards

1
Q

Transpumlomary pressure

A
  • difference between alveolar and pleasurable pressure
  • measure of force that collapses lung (recoil pressure)
  • increase in trans pulm pressure = more recoil pressure
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2
Q

Normal pleural pressure

A

-5 cm H20

Holds lungs open at rest

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3
Q

Inspiration

A
  • chest cavity expands…-7.5 cm H20 pleural pressure

- 500 mls air in (normal tidal volume)

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4
Q

Expiration

A
  • recoil back to resting

- 500 mls air out

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5
Q

Normal alveolar pressure

A
  • 0 cm H20

- atmospheric pressure

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6
Q

Change in alveolar pressure driven by:

A
  • Change in pleural pressure

- expansion/collapse of alveoli

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7
Q

Change in pleural pressure driven by:

A
  • change in thoracic cavity size
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8
Q

Length of expiration

A
  • 2-3 seconds
  • passive process
  • inspiration is only 2 sec….active process
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9
Q

What determines how fast alveolar pressure changes:

A
  • resistance
  • pressure gradient (transpulmonary pressure)
  • compliance of lungs
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10
Q

Lung compliance

A
  • 200 mls air for each 1 cm H2O increase

- transpulmonary pressure rises during inspiration

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11
Q

Compliance curve

A
  • shape determined by elastic forces of lungs
  • easier to move air out vs in (lungs want to collapse)
  • Inspiration: compliance starts low then high
  • Expiration: compliance starts high then low
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12
Q

Elastic forces affecting lung compliance

A
  • elastic forces of lung: -elastin/collagen fibers
    - 1/3 of elastic forces
  • elastic forces of air-fluid interface: -2/3 of forces
    - Becomes problem if no surfactant
    - 1-2 H2O molecules on alveoli
    - easier to breathe without interface
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13
Q

Surfactant

A
  • reduces water surface tension
  • secreted by type II epithelial cells
  • contains phospholipids
  • reduce tension 8-50%
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14
Q

Alveoli lined with water

A
  • on inside
  • helps with expiration
  • makes inspiration harder
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15
Q

Emphysema

A
  • merging of alveoli
  • good for collapsing pressure
  • lose more surface area…doesn’t make up for collapsing pressure
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16
Q

Collapsing pressure

A

2 x surface tension / alveolar radius

  • if collapsing pressure increases…harder to bring air in
  • normal is 4 cm H2O
  • if no surfactant… 18
  • if radius halved…36
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17
Q

Premature babies surfactant

A
  • forms in 6th or 7th month of gestation
  • radius less than 1/4 of adult
  • collapsing pressure 6-8 x greater than adult
  • respiratory distress syndrome can be fatal
    - treated with surfactant
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18
Q

Lungs+Thorax compliance

A
  • half of that of just lungs

- 110 mls / cm H2O (vs 200)

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19
Q

3 factors of energy needed to breath

A
  • force requires to expand lungs against elastic forces
    • increase compliance = less energy
  • tissue resistance work
  • airway resistance work (asthma)
  • 3-5% of total energy is for NORMAL ventilation (can increase 50x)
    • limitation of exercise is muscle energy for respiration
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20
Q

Spirometer

A
  • measures pulmonary volumes
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21
Q

Tidal volume

A
  • normal breath volume

- 500 mls

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22
Q

Inspiratory reserve volume (IRV)

A
  • full force of inspiration above tidal volume

- 3000 mls

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23
Q

Expiration reserve volume (ERV)

A
  • Max expiration after tidal volume

- 1100 mls

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24
Q

Residual volume (RV)

A
  • Air remaining after forced exhale
  • always there to prevent lungs from collapsing
  • keeps normal pO2 and pCO2
  • 1200 mls
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25
Q

Inspiratory capacity (IC)

A
  • TV + IRV

- 3500 mls

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26
Q

Functional residual capacity (FRC)

A
  • ERV + RV

- 2300 mls

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27
Q

Vital capacity

A
  • IRV + TV + ERV
  • 4600 mls
  • Total we can actually move
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28
Q

Total lung capacity (TLC)

A
  • VC + IRV

- 5800 mls

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29
Q

Raw

A

Airway resistance to flow

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30
Q

Vd

A

Volume of dead space gas

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31
Q

Va

A

Volume of alveolar gas

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32
Q

R

A

Respiratory exchange ratio

33
Q

Ppl

A

Pleural pressure

34
Q

Palv

A

Alveolar pressure

35
Q

Pb

A

Atmospheric pressure

36
Q

DL O2

A

Diffusing capacity of lungs for O2

37
Q

Vi

A

Inspired volume of ventilation per minute

38
Q

Vs

A

Shunt flow

39
Q

VO2

A

Rate of O2 uptake per minute

40
Q

Minute respiratory volume

A
  • New air into airway per minute
  • TV x respiratory rate
  • 500 x 12 = 6000 mls/min
  • respiratory rate can go as high as 40-50 bpm but not long
41
Q

Alveolar ventilation

A
  • new air into alveoli per minute
  • (TV-dead space) x resp rate
  • (500-150) x 12 = 4200 mls/min
  • determines pO2 and pCO2
  • increase pulm rate…increase O2 and decrease CO2
42
Q

Anatomical dead space

A
  • all space in resp system other than alveoli
  • where no gas exchange occurs
  • increases with age
43
Q

Physiological dead space

A
  • anatomical dead space + not functioning alveoli w/ no blood flow
  • normally just equal to anatomical dead space
  • in diseased can be up to 10x larger than anatomical dead space
44
Q

Bronchial circulation

A
  • high pressure, low flow
  • arterial blood to lung tissue (1-2% of CO)
  • arises from thoracic aorta
  • returns venous blood to pulmonary veins
    • deoxy blood merges with oxy blood
45
Q

Pulmonary circulation

A
  • low pressure, high flow
  • deoxy blood to pulmonary capillaries (gas exchange)
  • oxy blood to LA
46
Q

Pulmonary Artery

A
  • divides into R and L main pulmonary arteries
  • thin (1/3 of aorta) and distensible (7 mls/mmHg)
  • short
  • deoxy blood (75% O2 vs 99%)
47
Q

Bronchial arteries

A
  • 1-2 % of CO
  • carry O2 blood
  • supplies tissues of lungs
  • empty into pulmonary veins and enters LA (like a shunt)
    • so SV of LV is 1-2% greater than that of RV
48
Q

Lymphatics in the lungs

A

Jobs:

  • remove particulate matter entering alveoli (also coughing)
  • collect plasma proteins leaked from pulmonary caps (no edema)
  • empty into right thoracic lymphatic duct
49
Q

RV diastolic / RA pressure

A

0-1 mmHg

50
Q

RV systolic / PA pressure

A

25 mmHg

51
Q

Mean Pulmonary pressure

A

15 mmHg

52
Q

Left atrial pressure

A

2 mmHg

  • what we are trying to measure (filling pressure)
53
Q

PCWP

A

5 mmHg

-ca use as LA indicator…just a little higher (due to more resistance)

54
Q

Pulmonary capillary pressure

A

7 mmHg

55
Q

PA diastolic pressure

A

8 mmHg

56
Q

Blood volume in lungs

A
  • 9% of total blood volume
  • 450 mls (arts + caps + veins)
  • 70 mls in caps (alveolar SA is 770 - 1075 ft^2)
57
Q

Changes in pulmonary blood volume

A
  • can go from 1/2 to 2x normal
    • hard expulsion of air can move 250 mls blood out
  • L heart failure / mitral valve probs can increase resistance to flow out
    • can cause 100% increase (2x normal) in volume and pressure
    • drops gas exchange
58
Q

Compliance of pulmonary vessels

A
  • very high….unlike aorta

- minimizes high pressure risk for RV (want to keep low)

59
Q

Low O2 in alveoli

A
  • if pO2 < 73 mmHg…vessels constrict
  • stops flow to alveoli because poor gas exchange will happen
    • opposite of systemic caps
    • directs blood to better gas exchange areas away from dead space
60
Q

Hydrostatic pressure gradient

A
  • pressure under surface of water/air interface
  • pressure increases 1 mmHg / 13.6 mm depth
  • due to gravity / weight of water above
61
Q

Hydrostatic pressure gradient in body

A
  • RA: 0 mmHg (heart pumps excess blood)
  • Brain: 10 mmHg lower
  • Feet: 90 mmHg higher
62
Q

Hydrostatic gradient in lungs

A
  • top: 15 mmHg lower than level of heart
  • bottom: 8 mmHg higher than level of heart
  • total pressure difference = 23 from top to bottom
  • note that even though pressure changes at different levels…pressure gradient that drives movement through vessels stays same
  • flow at bottom of lungs would be higher than top if R stays same
63
Q

Pulmonary cap pressure depends on:

A
  • driving pressure from RV
  • effect of hydrostatic pressure
  • alveolar pressure in surrounding tissue
64
Q

Zone 1

A
  • top of lungs
  • no flow ever
  • alveolar pressure > pulm cap pressure
  • no zone 1 under normal conditions
    • will if low MAP or high alveolar pressure
65
Q

Zone 2

A
  • intermittent flow
  • pulm cap pressure > alveolar pressure …in systole only
  • little to no flow in diastole….opposite relationship
  • apex of lung
66
Q

Zone 3

A
  • continuous blood flow
  • pulm cap pressure > alveolar pressure
  • all of lung except apex (zone 2)
  • during exercise, blood flow increases…all areas become zone 3
67
Q

Ventilation vs perfusion

A
  • If only perfusion… only venous blood
    • pO2 and pCO2 will equilibrate
  • If only ventilation… alveoli constantly refreshed
    • pO2 and pCO2 max and min out…150 and 0
  • Normal Va/Q values = 104 and 40 (pO2 and pCO2)
68
Q

How lungs handle increase in CO

A
  • Exercise can increase CO 4-7x
  • Want to keep pulm pressures down…RV can’t handle
  • More caps open up (3x)
  • Distending open caps more (x2)
  • Increasing pulm art pressure
  • Increase in pulm pressure small compared to CO increase
  • prevents edema formation
69
Q

Pulmonary response to high LA pressure

A
  • Never above 6 mmHg
    • Pulmonary veins dilate in response to increase in pressure
  • In L side failure, LA can get to 40-50!
    • Increases right heart workload
    • above 25-30 mmHg causes pulmonary edema (dead < 30 min)
70
Q

Normal CO speed of blood in pulmonary caps

A

0.8 secs

  • As low as 0.3 with high CO
  • More caps open in high CO to prevent any lower than 0.3 secs
71
Q

Pulmonary capillary hydrostatic pressure vs systemic

A
  • Lower
  • 7 vs 17 mmHg
  • force pushing out of cap
72
Q

Pulmonary interstitial hydrostatic vs systemic

A
  • Lower
  • -5 to -8 vs -3
  • force pulling out
73
Q

Pulmonary interstitial oncotic vs systemic

A
  • higher
  • 14 vs 8 mmHg
  • leaky pulmonary caps
  • force pulling out
74
Q

Pulmonary plasma oncotic vs systemic

A
  • same
  • 28 mmHg
  • biggest one we affect
  • After all pressures added up….1 mmHg total outward force
  • Lymph ducts carry away excess fluid and also evaporation
75
Q

Acute pulmonary edema

A
  • occurs if increase rate of filtration
  • occurs if decrease rate of lymph removal
  • Causes:
    • L heart failure / mitral valve disease (increase LA pressure)
    • damage to cap membrane / pneumonia , toxic gases (pulm oncotic pressure decreases)
76
Q

Chronic pulmonary edema

A
  • lungs compensate if pulm cap pressure high for 2 weeks
  • lymph vessels expand…carry 10x normal
  • pressure of 40 mmHg and can still live
  • this needs to happen gradually over time
77
Q

Pleural fluid

A
  • few mls
  • kept at minimum by lymphatics
  • provides -4 mmHg to keep lungs expanded to normal size
78
Q

Pleural effusion

A
  • excess fluid in cavity
    Causes:
  • blockage of lymph vessels
  • heart failure w/ high pulm pressures
    • increased fluid/protein into pleural space
  • reduced plasma colloid pressure (perfusionist fault)
  • infection/inflammation of pleural membrane

556 - Physiology & Pathophysiology II (8 decks)

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