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HLB > Mechanics of Breathing, Pressures & Work > Flashcards

Mechanics of Breathing, Pressures & Work Flashcards

1
Q

FIO2

A

fraction of inspired oxygen

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2
Q

FRC

A

Functional Residual Capacity

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3
Q

Patm

A

atmospheric pressure

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4
Q

Ptp

A

transmural pulmonary pressure

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5
Q

Ppl

A

intrapleural pressure

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6
Q

Palv

A

intrapulmonary/intra-alveolar pressure

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7
Q

PTM

A

pressure at the mouth

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8
Q

RAW

A

airway resistance

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9
Q

RR

A

respiratory rate

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10
Q

RV

A

residual volume

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11
Q

TLC

A

Total Lung Capacity

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12
Q

Respiratory system slide

A

complete

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13
Q

Tidal Volume definition and is at rest

A

volume of each breath
500mL at rest

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14
Q

Dalton’s Law

A

when two or more gases which do not chemically react are present in the same container (lungs) the total pressure is the sum of the partial pressure of each gas

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15
Q

Dalton’s Law problem

A

complete

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16
Q

Boyle’s Law

A

pressure exerted by gas (CO2) in a closed container (lungs) is inversely proportional to the volume of gas in the container
occurs at a constant temperature

P is inversely proportional to V

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17
Q

Charles’s Law

A

V is proportional to T

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18
Q

Henry’s Law

A

Applies to gases dissolved in liquids
The number of molecules of a gas dissolving in the liquid is proportional to the partial pressure at the surface of the gas = solubility

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19
Q

Inspiration:

  • intercostal muscles —– and —– the ribs
  • diaphragm moves —-
  • Scalene muscles inserted into ribs —- and —–, ——— the upper ribs and ——- the sternum ——- in —— action, which —— the anterior-posterior diameter of the thoracic cavity
  • sloping lower ribs rise and move out = ———- action and increases the ——— diameter of the chest wall
A
  • elevate and evert
  • downward
  • 1 & 2, raising, pushes, forward, pump, increases
  • bucket handle, transverse
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20
Q

What percentage increase in volume when the diaphragm contracts?

A

75%

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21
Q

At the end of inspiration, pressures are equal.

True or False?

A

True

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22
Q

Expiration occurs due to

A

elastic recoil of the lungs and the chest wall

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23
Q

Forced contraction (eg: ——-) requires

A
  • coughing/sneezing
  • contraction of the abdominal walls, which push the diaphragm upward
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24
Q

During forced expiration, intrapleural pressures may rise to

A

+8kPa
60mmHg

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25
Q

Intrapleural pressure equilibrates with the atmosphere.

True or False?

A

False

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26
Q

Why does intrapleural pressure not equilibrate with the atmosphere?

A

As the pleural space is closed and fluid filled, it is slightly sub-atmospheric due to the recoil of the chest and lungs away from each other - stops the lungs from collapsing.

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27
Q

Ptp: Transmural Pulmonary Pressure is

A

The distending pressure on the pleural space, which is transmitted to the alveoli to increase their volume, lower the pressure and generate airflow inwards.

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28
Q

Under physiological conditions (quiet breathing):

Ptp: Transmural Pulmonary Pressure is always positive or negative?

A

Positive

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29
Q

Under physiological conditions (quiet breathing):

Ppl: Intrapleural Pressure is always positive or negative?

A

Negative

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30
Q

Under physiological conditions (quiet breathing):

Palv: intrapulmonary/alveolar pressure is always positive/negative?

A

Moves from slightly negative to slightly positive as we breathe, it is always higher than the intrapleural pressure because of the recoil of the lungs; it is 0 at the end of inspiration and expiration, so there is no airflow

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31
Q

For a given lung volume, the Ptp; the transmural pulmonary pressure is less than the elastic recoil pressure of the lung.

A

equal and opposite to the elastic recoil pressure of the lung.

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32
Q

What “sucks the lungs out and sucks the lungs back in”?

A

transmural pulmonary pressure
Ptp
ensures the lungs don’t collapse

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33
Q

During inspiration, atmospheric pressure in relation to alveolar pressure

A

greater
hence air flows in

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34
Q

At the end of expiration, atmospheric pressure in relation to alveolar pressure

A

equal, FRC, no air flow, outward and inward recoil of lungs are equal

35
Q

FRC: Functional Residual Capacity

A
  • volume of air left in the lungs at the end of a normal breath
  • at FRC respiratory muscles are relaxed and the lungs and the chest wall recoil in opposite directions and inward and outward recoil are exactly balanced
36
Q

Volume of FRC is determined by the

A

elastic properties of the lungs and the chest wall

37
Q

Pulmonary Fibrosis affecting FRC

A
  • lungs are stiff and small
  • increase in elastic recoil
  • decrease in FRC
38
Q

Emphysema affecting FRC

A
  • loss of alveolar tissue, break down of alveolar sacs
  • decrease in elastic recoil
  • increase in FRC
39
Q

Impedance

A

Frictional Airway Resistance and Elastic Resistance to the stretching of the lungs and chest wall

40
Q

inspiratory muscles contract to overcome the —— offered by the lungs and chest wall.

A

impedance

41
Q

Lung compliance refers to

A

the ability of the lungs to stretch and recoil during ventilation

42
Q

CL =

A

change in lung volume/unit change in distending pressure

43
Q

The distending pressure is

A

the pressure difference across the lung = alveolar-intrapleural pressure

44
Q

Static pressure-Volume loop

A
45
Q

A dynamic pressure volume loop is obtained from

A

continuous measurements of intrapleural pressure and volume during a normal breathing cycle

46
Q

How can we find dynamic compliance from a dynamic pressure-volume loop?

A

At the end of inspiration airflow is 0
At the end of expiration alveolar pressure is 0
The slope of the line joining these points is the dynamic compliance

47
Q

In lung diseases (stiff lungs) dynamic compliance is similar to static compliance.

True or False?

A

False
- in healthy lungs are similar
- different in stiff lungs

48
Q

In lung diseases (stiff lungs) dynamic compliance is similar to static compliance.

True or False?

A

False
- in healthy lungs are similar
- different in stiff lungs

49
Q

What is hysteresis?

A
  • frictional resistance changes, hence compliance curves are different for inspiration and expiration.
50
Q

Is the lung more or less compliant at higher volumes?

A

Less compliant

51
Q

altered lung compliance in lung disease

A
52
Q

altered lung compliance in lung disease

A

insert

53
Q

altered lung compliance in disease

A

enter

54
Q

Laminar and Turbulent Flow

A

during quiet breathing there is laminar air flow in airways
gas particles move parallel to the walls of bronchi
center layers move faster than outer ones creating a cone shaped front
turbulent flow occurs at higher linear velocities in wide airways and near branch points
Turbulent flow occurs in the trachea during exercise

55
Q

laminar and turbulent airflow diagram

A
56
Q

RAW: Airway Resistance

A
  • originates from friction between air and mucosa
  • affects ventilation and has to be overcome along with elastic recoil and inflate the lung
  • pressure difference between the alveoli and mouth divided by the flow rate
  • inversely proportional to the 4th power of the radius
  • inversely proportional to the viscosity of fluid
57
Q

How can RAW be indirectly assessed?

A

From Forced Expiratory Measures (FEV1,FVC, FEV1/FVC)

58
Q

airflow equation

A

(mouth-alveolar pressure)/RAW

59
Q

Halving radius of airway increases laminar flow (airway resistance) by

A

16x

60
Q

Which areas offer the most resistance during respiration?

A

Nose, pharynx and trachea

61
Q

Mouth breathing (eg: during exercise) increases or decreases resistance?

A

Decreases

62
Q

Disease that affects peripheral, smaller airways effect on RAW?

A

Increases airway resistance

63
Q

Tone of bronchial smooth muscle and epithelium as a factor affecting laminar flow

A

parasympathetic nerve supply affects bronchomotor tone (Ach and M3 receptors)
Beta adrenergic receptors activated, cause relaxation (broncho)

64
Q

mmHg is the millimeters of mercury and is used for

A

blood pressure

65
Q

SI unit of pressure is, which is equal to

A

1 pascal = 1Newton per m^2

66
Q

cmH2O used for

A

Intrapleural Pressure
Central Venous Pressure

67
Q

Inspiration and Expiration are active processes.

True or False?

A

False

Expiration is a passive process

68
Q

inspiratory muscles diagram

A
69
Q

Q =
flow rate =

A

Q = (piPr^4)/8nl
flow rate = (pipressureradius^4)/ (8fluid viscositylength of tubing)

70
Q

Nitric Oxide causes bronchodilation or bronchoconstriction?

A

Bronchodilation

71
Q

Resting bronchomotor tone during bronchoconstriction:

  • radius
  • resistance
  • airflow
A
  • radius decreases
  • resistance increases
  • airflow decreases
72
Q

Resting bronchomotor tone during bronchodilation:

  • radius
  • resistance
  • airflow
A
  • increases
  • decreases
  • increases
73
Q

Acute Asthma affecting RAW:

A
  • bronchonstriction
  • mucosal oedema
  • mucus hypersecretion
  • mucus pluggin
74
Q

COPD affecting RAW:

A
  • bronchoconstriction
  • chronic mucosal hypertrophy
75
Q

Surface Tension in lungs are caused by

explain

name

A

air-fluid interface in alveoli

cohesive forces between molecules at the surface of an alveolus creates a tension that causes the alveolus to shrink

Alveoli and small airways are inherently unstable and can collapse during expiration = atelectasis

76
Q

Surface tension of alveolus changes with (2)

A

age
disease

77
Q

Pulmonary Surfactant is

A

a mixture of phospholipids (phosphatidylcholine and proteins)

78
Q

Where is pulmonary surfactant found?

A

Floats on the surface of alveolar fluid

79
Q

Pulmonary surfactant are produced by

A

Type 2 pneumocytes

80
Q

How does pulmonary surfactant reduce surface tension?

A

Hydrophilic and Hydrophobic ends repel each other and interfere with liquid molecule attraction, which lowers surface tension.

81
Q

Why is pulmonary surfactant important? (5)

A
  • increases lung compliance by reducing surface forces
  • promotes alveolar stability
  • prevents alveolar collapse as small alveoli do not get smaller and large alveoli don’t get bigger
  • reduces surface tension which reduces hydrostatic pressure in tissue outside capillaries and hence keeps lungs dry
  • important defense against infection
82
Q

How does pulmonary surfactant help keep the lungs dry?

A
  • surface tension will suck fluid from the capillaries into the alveoli
  • reduction of the surface tension reduces the hydrostatic pressure in tissue outside capillaries and keeps the lungs dry
83
Q

Lack of surfactant in premature babies (<28 weeks) causes

A

neonatal respiratory distress syndrome

84
Q

lung volume and capacity

A

HLB (49 decks)

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