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physiology IV > Pulmonary Mechanics I > Flashcards

Pulmonary Mechanics I Flashcards

1
Q

The lung is a negative or positive pressure pump?

A

Negative - inflates due to a drop of intrapleural P outside the lung

-instead of inc in P w/in lung

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2
Q

What is the function of the external intercostals?

A
  • inspiration during active breathing during exercise
  • Lifts ribs up and forward
  • Increases anterior-posterior dimension of chest cavity
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3
Q

What is the function of the diaphragm?

A
  • Primary muscle of inspiration

- When it contracts - increases volume of chest cavity

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4
Q

Name some accessory muscles of inspiration?

A
  1. Sternomastoid - lifts sternum
  2. Scalene - lifts upper ribs

others in the face, neck, head

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5
Q

What is the function of the internal intercostals?

A
  • involved in passive expiration

- lowers the ribs

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6
Q

Name some abdominal muscles, involved in expiration?

A
  1. Rectus abdominus
  2. External and internal obliques
  3. transversus abdominus
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7
Q

What is eupnea?

A

Normal breathing at a rate of 7.5 mL/min

  • active inspiration, passive expiration
    • usually only diaphragm for inspiration
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8
Q

What is hyperpnea?

A

-active breathing during exercise - up to 120ml/min
-inspiration is aided by the external intercostals
-expiration is aided by internal intercostals
& major abdominal muscles

-BOTH inspiration and expiration are active

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9
Q

What is tachypnea?

A

When breathing is more rapid than normal

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10
Q

What is hypoventilation?

A
  • not breathing enough
  • leads to alveolar hypoxia and hypercapnea respiratory acidemia
    • -too much CO2 present
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11
Q

What can cause hypoventilation?

A

Muscular dystrophy or respiratory muscle paralysis

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12
Q

What is hyperventilation?

A

Breathing faster than required for oxygenation

  • alveolar hypocapnea, repiratory alkalosis
  • CO2 is below normal range
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13
Q

What can cause hyperventilation?

A

anxiety or a panic attack

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14
Q

What is the relationship between alveolar pressure and atmospheric pressure during inspiration? during expiration?

A
  1. Inspiration - Palv < P atm

2. Expiration - Palv> Patm

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15
Q

What is the goal of an esophageal balloon?

A

To measure Ppl (intrapleural P)

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16
Q

What is transmural chest wall pressure equal to? What does the value tell us?

A

Pc = Ppl - Patm

-sets degree of inflation of the chest wall

17
Q

When is the transmural chest wall pressure negative?

A

At rest

18
Q

What is transmural lung pressure equal to? What does the value tell us?

A

Pl = Palv - Ppl

-sets degree of inflation for the lung

19
Q

What is total transmural P equal to?

A

Pt = P alv - Patm = Pc + Pl

20
Q

When does total transmural P equal zero?

A

At equilibrium when all muscles are relaxed

Pc = -Pl

21
Q

What does a spirometer measure? How is it performed?

A
  • Compliance

- inspires then holds breath with glottis open and breaths out

22
Q

What is the equation for compliance?

A

Change in volume / change in transmural P

same as:
change in volume / change in Palv

23
Q

What is FRC?

A

Lung volume when Pt = 0

  • occurs at end expiratory position
  • value is 36% of the vital capacity
24
Q

What forces exist with large lung volumes or Pc>0?

A 
-Elastic recoil of :
     Lungs
     Chest wall 
-Both point inwards 
-provide passive expiration
25
Q

What forces exist when lung is expanded to resting position of chest wall or Pc =0?

A

-Only elastic force of the lung opposes inspiration

26
Q

What forces exist at FRC - Pc =-Pl (Pc<0)?

A
  • outward elastic recoil of wall
  • inward elastic recoil of lung

-equilibrium

27
Q

What is occuring during emphysema?

A
  • alpha antitrypsin usually inhibits neutrophilic proteases
  • smoke inhibits alpha antitrypsin
  • compliance is elevated - so are FRC, TLC
  • exhalation is difficult
28
Q

What is Pneumoconioses?

A
  • inhalation of dust
  • formation of granulomas, fibrous tissue
  • decreased compliance
  • inhalation is difficult
29
Q

A saline filled alveoli has eliminated surface tension and therefore has what effect on compliance?

A

Increased compliance

30
Q

What is the purpose of surfactant?

A

Lowers surface tension and increases compliance

31
Q

What is atelectasis?

A

partial collapse of the lung

32
Q

Smaller bubbles have decreased or increased pressure?

A

Increased - due to smaller radius

33
Q

Describe a small and large bubble with surfactant?

A
  • equal pressures
  • smaller bubble - inc P due to smaller r
  • larger bubble - inc surface tension
    • less surfactant per unit area
34
Q

What forces exist during forced expiration, at lung volumes below FRC?

A

-only one is expansive force of lungs outwards

physiology IV (40 decks)

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