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24 A&P II > Lecture 11 & 12: Pulmonary (Exam II) > Flashcards

Lecture 11 & 12: Pulmonary (Exam II) Flashcards

1
Q

What is normal alveolar ventilation (V̇A) ?
How is it calculated?

A
  • 4.2 L/min
  • VA x resp rate = V̇A
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2
Q

What is the highest that PAO₂ can be at room air O₂ concentrations at normal atmospheric pressure? Why?

A
  • 150mmHg
  • Cannot be higher than 150mmHg due to this being the oxygen concentration of the air.
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3
Q

What is the lowest that PAO₂ can be (and still have life)?

A

40mmHg

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4
Q

What could cause a left shift on the PAO₂ curve below?

A
  • ↓ V̇A
  • ↑ metabolism
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5
Q

What could cause a right shift on the PAO₂ curve below?

A
  • ↑ V̇A
  • ↓ metabolism
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6
Q

A decrease in V̇A would cause a __________ in PACO₂.

A

Increase

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7
Q

An increase in V̇A would cause a __________ in PACO₂.

A

decrease

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8
Q

What is the percentage of O₂ in a humidified inspiration?

A

19.69%

↓

149.7 ÷ 760 = 19.69%

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9
Q

How much of of an VA inspiration is O₂?

A
  • 68.9 mL O₂

350mL x [0.1969] = 68.915 mL O₂

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10
Q

How much of VA O₂ (in mLs) leaves per exhaled breath?

Assume PAO₂ = 104mmHg

A

PAO₂ after equilibrium = 104mmHg
↓
104mmHg ÷ 760mmHg = 0.1368 O₂ content.
↓
350mLO₂ x 0.1368 = 47.88 mLO₂
=
47.88 mL O₂ is unabsorbed with each breath.

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11
Q

How much of VA O₂ (in mLs) is absorbed per breath?

Assume PAO₂ = 104mmHg

A

Total inspired O₂ per breath = 68.915 mLO₂
↓
Total expired O₂ per breath = 47.88 mL O₂
↓
68.915 - 47.88 mLO₂ = 21.035 mLO₂ absorbed per breath.

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12
Q

How much total O₂ is exhaled per breath?

A

VA = 350mL
VD = 150mL
↓
350mL x 0.1368[O₂] = 47.88mLO₂
+
150mL x 0.1969[O₂] = 29.54mLO₂
↓
= 77.42 is the total O₂ (both VA and VD) expired per breath.

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13
Q

How much CO₂ is exhaled per minute?

Assume the patient has a respiratory rate of 12bpm and give your answer in liters.

A

PACO₂ = 40mmHg
↓
VD CO₂ content = 0
+
VA CO₂ = 40mmHg ÷ 760mmHg = .0526
↓
350mL x 0.0526[CO₂] = 18.42mLCO₂
↓
18.42mLCO₂ x 12bpm = 0.221 Liters of CO₂ per minute.

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14
Q

What is the compliance of the lungs based on graph below?

A

ΔV / ΔP = Compliance
0.5L / 2.5cmH₂O = 0.2L/cmH₂O

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15
Q

What is normal lung compliance?

A

0.2 L/cmH₂O

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16
Q

An increase of 1cmH₂O in pulmonary compliance creates an increase in pulmonary volume by _________.

Assume normal physiology

A

200mLs

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17
Q

A decrease in pulmonary compliance by 2 cmH₂O results in a ________ in pulmonary volume by _________mls.

Assume normal physiology.

A

decrease: 400mLs

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18
Q

What occurs with very small airways in the lungs when we have low lung volumes?

A

Small airways can collapse

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19
Q

What lung volumes can normal spirometry not measure?

A

Residual Volume (RV) and thus FRC and TLC as well.

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20
Q

How can FRC be measured utilizing spirometry?

A

Helium spirometry.

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21
Q

Suppose you had a spirometer of 10L with a Helium concentration of 10%.

After being attached to a patient and a respiratory cycle, the helium concentration becomes 8%.

What is the patient’s FRC?

A

1L He starting out
↓
0.08 * x = 1L He
↓
x = 12.5 (new total volume)
↓
12.5 - 10 = 2.5L = FRC

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22
Q

What is the 2nd leading cause of lung cancer?

A

Radon

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23
Q

What would occur with the elasticity of lung tissue with emphysematous lungs?

A

↓ PER

Therefore, more compliant.

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24
Q

What would occur with the elasticity of lung tissue with fibrotic lungs?

A

↑ PER

Therefore, less compliant.

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25
Q

What would occur with alveolar size in fibrotic lungs? Why?

A

Alveolar size would decrease due to excessive PER.

26
Q

What would occur with alveolar size in emphysematous lungs? Why?

A

Alveolar size would increase due to loss of PER.

27
Q

Would total lung capacity (TLC) be increased or decreased (compared to normal lungs) at 30 cmH₂O in fibrotic lungs?

A

TLC would be decreased

28
Q

Would total lung capacity (TLC) be increased or decreased (compared to normal lungs) at 30 cmH₂O in emphysematous lungs?

A

TLC would be increased

29
Q

What pulmonary pressure works against PER?

A

PIP

30
Q

What are the two components affecting lung PER and compliance?
Which one has the greater effect?

A
  1. Surface Tension (⅔ of PER)
  2. Tissue Elasticity (⅓ of PER)

PER or compliance? or both?

31
Q

Why is there such a difference in the pulmonary compliance of an air-filled vs a saline-filled lung?

A

There is a no air-water interfaces and thus no of surface tension in the saline filled lung.

32
Q

At what pressures is the lung most compliant during inspiration?

A

~ 9-16 cmH₂O

33
Q

At what pressures is the lung least compliant during inspiration?

Why is this?

A

~ 0-8 cmH₂O

Lack of surfactant could be the cause of this period of non-compliance.

34
Q

What term describes the change in lung behavior seen between inspiration and expiration?

A

Hysteresis

35
Q

What substance counteracts the air-water interface surface tension?

A

Surfactant

36
Q

What type of cell produces surfactant?

A

Type II cuboidal alveolar cells

37
Q

What type of cell participates in gas exchange?

A

Type I alveolar cells

38
Q

Which of the lung capacity figures below is indicative of obstructive disease? Why?

A

Trapping of air noted by the massively increased RV.

39
Q

Which of the lung capacity figures below is indicative of restrictive disease? Why?

A

All lung volumes are decreased with no noted air trapping as seen with obstructive disease.

40
Q

Which surfactant protein molecules are hydrophilic?
Which are hydrophobic?

A
  • Hydrophilic: A & D
  • Hydrophobic: B & C
41
Q

What molecule forms the basis for most pulmonary surfactants?

A

Phosphatidylcholine

42
Q

All lung pathologies feature a deficiency in __________.

A

surfactant

43
Q

What composes surfactant?

A

Lipids (90%)
Proteins (10%)

44
Q

What do the surfactant lipids do?

A
  • Lower surface tension
  • Limit lymphocyte cytotoxicity.
45
Q

What do the surfactant proteins do?

A
  • Enhance chemotaxis & phagocytosis.
  • Aggregate & opsonize micro-organisms.
  • Inhibit bacterial growth.
46
Q

A strong IC is indicative of what?

A

Good lungs

A poor IC is highly correlated with bad lungs.

47
Q

What prevents autodigestion of the lungs via proteases?

A
  • α1AT (α-1 Antitrypsin)
48
Q

How can EtOH abuse lead to damaged lungs?

A

The liver produces α1-AT, without this molecule, the lungs will undergo proteolysis.

49
Q

What sort of pathology is seen from a lack of α1-AT?

A

Emphysema
- Lack of small alveoli
- Any alveoli left are distended and dysfunctional

50
Q

What cells package surfactant for release into the air-water interface?

A

Lamellar bodies

51
Q

What are the two components that make up a V/Q ratio?

A

V̇A = 4.2L/min
Q = 5L/min

52
Q

What is a normal V/Q ratio?

A

V/Q = 4.2/5 = 0.8

53
Q

What would a V/Q of 0 indicate?

A

0/5 so there is no airflow. Perfusion is occurring with no ventilation. Likely an airway obstruction.

54
Q

What would a V/Q of ∞ indicate?

A

4.2/0 so there is no blood flow. Ventilation is occurring with no perfusion. Likely something like a pulmonary artery embolus.

55
Q

What would PACO₂ and PAO₂ be in the event of a pulmonary embolus? Why?

A

PAO₂ = 150mmHg
PACO₂ = 0 mmHg

No change in either number from room air due to no gas exchange occurring.

56
Q

What would PACO₂ and PAO₂ be in the event of an acute airway obstruction? Why?

A

PAO₂ = 40mmHg
PACO₂ = 45 mmHg

No change in either number from returning mixed venous blood due to no fresh air reaching the alveolus.

57
Q

In normal physiology, an increased V/Q ratio would be seen at the _____ of the lungs.

A

Apex

58
Q

In normal physiology, a decreased V/Q ratio would be seen at the _____ of the lungs.

A

Base

59
Q

V/Q matching tends to _______ as we get older.

A

decrease

60
Q

Anesthesia will induce _____ lung volumes

A

low

61
Q

What change occurred between these two graphics?

A

Artificial PEEP was introduced to improve V/Q matching by increasing V̇A.

24 A&P II (24 decks)

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