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(OMS1) CPR Exam 1 > Lecture 1: Respiratory Cycle and Mechanics > Flashcards

Lecture 1: Respiratory Cycle and Mechanics Flashcards

1
Q

What does Boyle’s law say?

A

Pressure of gas is inversely proportional to volume

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2
Q

What happens when lung volume increases?

A

Pressure in lungs decrease so air can enter lungs

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3
Q

What happens when lung volume decreases?

A

Pressure in lungs increases so air can exit lungs

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4
Q

What happens during inspiration?

A
  • Inspiratory muscles (external intercostal muscles) contract
  • Diaphragm descends
  • Thoracic volume increases
  • Intrapleural pressure and alveolar pressure decreases
  • Chest wall and lungs will expand due to coupling (lungs want to collapse)
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5
Q

Where is parietal fluid found?

A

Between parietal and visceral pleura

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6
Q

What is intrapleural pressure?

A

Pressure everywhere in thorax except lumens of blood vessels, lymphatics, and airways

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7
Q

What is the intrapleural pressure at rest?

A

-5 cm H2O

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8
Q

What is the intrapleural pressure during inspiration?

A

Reaches -8 cm H2O

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9
Q

What is the alveolar pressure at rest?

A

0 cm H20

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10
Q

What is the alveolar pressure during inspiration?

A

-1 cm H20

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11
Q

What happens during inspiration?

A
  • Passive so expiratory muscles not always used
  • Diaphragm ascends
  • Thoracic volume decreases
  • Intrapleural pressure and alveolar pressure increases
  • Chest wall and lungs will shrink due to coupling
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12
Q

What is the intrapleural pressure during expiration?

A

Goes back to rest (-5 cm H2O)

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13
Q

What is the alveolar pressure during expiration?

A

Reaches +1 cm H2O

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14
Q

What four things does the respiratory cycle show change in?

A

1) Volume
2) Alveolar Pressure
3) Intrapleural Pressure
4) Air Flow

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15
Q

What is minute ventilation?

What is the normal value?

A

Volume of air inhaled every minute

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16
Q

How do you calculate minute ventilation?

A

V(dot) = Tidal Volume x frequency

17
Q

What is the normal value of minute ventilation?

A

7 L/min

18
Q

What is anatomic dead space?

A

Space in the lungs designed not exchange oxygen

  • first 16 generations of airway do not have alveoli
  • called anatomic since it is not designed for air exchange
19
Q

How do you calculate anatomic dead space?

A

Weight of person –> anatomic dead space

Example: 120 lb person has 120 mL of anatomic dead space

20
Q

What is alveolar dead space?

A

Alveoli that receive air but not blood

-this should in theory not exist

21
Q

What is physiological dead space?

A

Dead alveolar space so no gas exchange

-this should in theory not exist

22
Q

How do you calculate minute alveolar ventilation?

A

V(dot alv) = (Tidal volume-anatomic dead space volume) x (frequency)

23
Q

When is it easiest for lungs to stretch during inspiration?

A

After there is a little air in the lungs, a small change in pressure can lead to a huge increase in volume of lungs

24
Q

What is hysteresis?

A

Difference between inspiration and expiration

25
Q

What allows hysteresis to occur?

A

Surfactant: reduces tension and helps air reach all alveoli

26
Q

What is compliance?

A

Measure of stretch ability of lungs

27
Q

Where is compliance high in lungs?

A 
Tidal volume (middle)
-easy to inflate
28
Q

How is compliance calculated?

A

Compliance = (Δ volume)/(Δ pressure)

29
Q

What is the opposite of compliance?

A

Elasticity: recoil ability

30
Q

How does fibrosis affect compliance?

A

Lowers compliance

-lungs have to work harder to bring in air

31
Q

How does age affect compliance?

A

Compliance increases with age

-less elastin and more collagen

32
Q

How does emphysema affect compliance?

A

Increases compliance

-easier to bring air but air has no where to go since there is an increase in dead space

33
Q

Where do recoil of lungs and chest wall balance each other?

A

Functional residual capacity (FRC)

34
Q

When a pneumothorax occurs, what happens to chest wall and lungs?

A

Lungs: get smaller
Chest wall: expand
*both get their wish

35
Q

How is airway resistance calculated?

A

Resistance = (8 x viscosity of x length of tube) / (radius^4)

36
Q

What prevents alveoli to collapse?

A

Interdependence

-shared walls of alveolar and airways prevent collapse as recoil opposes each other

(OMS1) CPR Exam 1 (30 decks)

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