Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CSF3 Exam 2 > Pulmonary Mechanics II: Dynamic- Johnson > Flashcards

Pulmonary Mechanics II: Dynamic- Johnson Flashcards

1
Q

The bulk movement of air from the external environment to the internal air spaces require what 3 opposing forces be overcome?

A
  1. elastic recoil of lungs and chest wall which depend on lung volume and are not affected by motion
  2. inertance or impedance of acceleration of the respiratory system which depends on the rate of airflow
  3. frictional resistance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the MAJOR force that must be overcome in movement of air? How is this force determined?

A

frictional resistance which is determined by airflow and not by a change in lung volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Dynamic lung mechanics deals with properties of airflow in what cylindrical tubes of the respiratory tract?

A

trachea, bronchi, bronchioles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Airflow is established by what?

A

pressure gradient (goes from high to low) that is generated by diaphragm contraction

alveolar pressure and barometric pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

If barometric pressure exceeds alveolar pressure, where does air go?

A

air goes into the lung

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

If alveolar pressure exceeds barometric pressure, for example at the end of inspiration, where does air go?

A

air exits the lung

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 3 types of airflow in the bronchi? What are characteristics of each?

A

laminar: movement of air is parallel to air wall; usually occurs in smaller airways; where gas exchange occurs
turbulent: airflow is perpendicular, parallel, just erratic/chaotic type of air flow; use Reynold’s number to determine when we will see this type of flow; larger airways: nose, trachea, primary bronchi more readily experience this
transitional: due to several branching points in the bronchial division so air has to enter into smaller and smaller bronchial tubes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

T/F Laminar flow has better driving force than turbulent flow.

A

TRUE

there is a greater driving pressure than any instance where there is turbulent flow

  • driving pressure for laminar flow is proportional to gas viscosity
  • driving pressure for turbulent flow is proportional to square of flow and is dependent on gas viscosity
  • driving pressure for transitional flow is proportional to both gas density and gas viscosity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What type of flow can you have with mucus plugs, inflammation or with any obstruction?

A

transitional or turbulent flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Reynold’s number (Re)

A 
Re = 2rvd/η
“r” is the radius
“v” is the average velocity
“d” is the density 
“η” is the viscosity
  • used to calculate whether you’ll have turbulence
  • turbulence most likely to occur where average velocity is high and radius is large (upper airway)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What type of gas are often used in treatment for asthmatics?

A

usually during an asthma attack you want to reestablish the airway,
low density gas such as helium (to deliver the O2) which is much less likely to cause turbulence thus lower Reynold’s number

the conducting zone is being blocked and thus O2 cannot get into the respiratory zone alveoli and thus you cannot get O2 to your blood and thus to your tissue which will suffer from hypoxia

Low density gas such as helium is much less likely to cause turbulence at any given flow rate. (often used in treatment)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What produces sound when listening to airflow?

A

irregularities in wall surfaces which produces turbulent flow; laminar flow is silent which presents a challenge in identifying small airway disease

bronchitis is a very noisy auscultation; in asthma you will hear wheezing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Much of the small airways will be arranged in series or parallel? Why is this significant?

A

in parallel which is significant physiology because it reduces total resistance of smaller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is stridor?

A
  • usually occurs in infants
  • noisy breathing with high pitched crowing sound
  • laryngomalacia meaning soft larynx; immature cartilage of the upper larynx collapses inward during inhalation, causing airway obstruction
  • obstruction to airway will produce turbulent flow (and audible sounds) in attempt to force their way through narrow breathing passages
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the resistance develop in respiratory tubes?

A 
obstruction
inflammation in the air way 
mucus production
bronchitis 
asthma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Much of the resistance come from what structures in the respiratory system?

A

rigid structures that have cartilage like the trachea in the very early upper airway; these structures are arranged in series contributing to resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When considering resistance what are factors to consider?

A
  • larger diameter: cartilaginous tubes greater than 2mm in diameter)
  • cross-sectional area
  • arrangement: series
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the conducting zone?

A

where you have the majority of the tubes that do not participate in gas exchange; they serve as a conduit for the gas to reach the respiratory (gas exchange) zone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why does airway resistance significantly drop from conducting zone in the upper airways to the respiratory zone?

A

shift from series to parallel arrangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

T/F Small airways do make a significant contribution to total airway resistance.

A

FALSE

Small airways do not make a significant contribution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the change in the surface area as you go from the conducting zone to the gas exchange zone?

A

it increases to about the size of a tennis court

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are poor indicators of airway resistance?

A

Terminal and respiratory bronchioles as they have very little resistance and have laminar flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the normal resistance of the respiratory system?

A

2 cm H2O/L*sec

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the percentage contribution of airways to the total resistance in the respiratory system?

A
  • large airways: 80%
  • medium airways: 15%
  • small airways: 5%

this all speaks to the arrangment of the tubes series (resistance) vs. parallel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Relate resistance, pressure, and flow.

A

resistance is proportional to pressure but inversely proportional to flow

Resistance= Pressure/Flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The air flow rate is higher in which part of the respiratory cycle?

A

inspiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The resistance is higher in which part of the respiratory cycle?

A

expiration as the flow rate is slightly slower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Of the factors contributing to total airway resistance: number, length and cross-sectional area, which is the most important?

A

cross-sectional area because resistance is inversely proportional to the fourth power radius of the airway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Airways lengthen during _____ and shorten during ________with the phases of respiration.

A

inspiration

expiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

The number of airways is established by what week of gestation. How does length of conducting airways vary from individual?

A
  • 16th week

- dependent on age, body size, and phase of respiratory cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the two opposing forces that control cross-sectional area?

A
  • inward traction from airway smooth muscle and elastic forces
  • outward traction by alveolar septae and transpulmonary pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Which force contributing to the cross-sectional area predominates with reduction in airway size?

A

inward traction; elastic forces in wairay and tension of airway smooth muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Which force contributing to the cross-sectional area predominates with expansion in airway size?

A

positive transpulmonary pressure or from interdependence of alveolar and terminal bronchioles

34
Q

What is the collateral way in which air can get to gas exchange zone?

A

canals of Lambert, pores of Kohn

35
Q

Increased volume increases caliber??? of the airway and decreases resistance vice versa. Explain. ????

A
  • when you’re taking in air or there is a larger amount of air in airway and thus less resistance
  • but there is increase in resistance as you approach RV because at very low lung volumes you start to get a narrowing airways changing the diameter and increasing the resistance

Airway mucus, edema, contraction of bronchial smooth muscle all decrease the caliber of the airway and cause an increase in total airway resistance.

36
Q

How does resistance change at volumes above FRC?

A

no significant changes as FRC is the starting level of every inspiratory effort because air is not really moving in or out

37
Q

How does conductance relate to lung volume and resistance?

A

-linear increase in conductance
as the volume increases and resistance decreases

-decreased lung volumes reduces conductance as you are running out of air and have no more air to expel

38
Q

Why do individuals with increased resistance tend to breathe at higher lung volumes?

A

it takes much more time to get air out if something is obstructing blood flow

39
Q

What is Poiseuille’s law about?

A
  • density and viscosity of the inspired air affects resistance
  • increased gas density increases airway resistance
40
Q

Status Asthmaticus is a clinical condition characterized by?

A

bronchospasm, edema and mucus in the airway resulting in increased total airway resistance

41
Q

How does elastic recoil affect the airway resistance?

A

during eupneic breathing (when flow is not limited) elastic recoiling will determine airway resistance

42
Q

Describe the neuronal innervation to the airways.

A

neurohumoral regulation of
airways include:

  • stimulation of vagal afferents (parasympathetic, constrictors)
  • reflex or direct stimulation via irritants, smoke, cold air, dust causing constriction of airway (increased resistance)
  • histamine, Ach, leukotrienes released from mast/epithelial cells of the airway acting on smooth muscle causing constriction
  • sympathetic system reduces airway resistance (dilators)
43
Q

What is the test used when figuring if a patient has asthma or not?

A

Methacholine (Provocholine®), a histamine-like compound is used to assess airway hyperresponsiveness (commonly observed in status asthmaticus)

Asthmatic patients exhibit responsiveness at much lower concentrations (asthmatics will respond quicker) than
normal subjects

44
Q

How does the parasympathetic and sympathetic system innervate the airways?

A

Parasympathetic:

  • contraction of smooth muscle
  • viscous secretion -increase airway inflammation

Sympathetic:

  • relaxation of the smooth muscle
  • watery secretion
45
Q

What is definition of compliance? How is this different from DYNAMIC compliance?

A
  • compliance is the change in lung volume resulting from a change in 1 cm H2O in the distending pressure
  • dynamic compliance is the change in volume of the lungs divided by the distending pressure during the course of a breath
46
Q

Why is the lung less compliant at lower volumes?

A
  • because there is less surfactant at the air-liquid interface; that results in higher surface tension
  • at large lung volumes more surfactant reaches the surface of the alveoli and this facilitates expansion of the lungs; less surfactant is available during tidal volume
47
Q

What is the relationship between compliance and resistance and how it impacts filling of alveoli?

A

Situation A: both alveoli have a common conduit and have equal resistance and compliance and thus both alveoli would fill with the same time constant

Situation B: both units have the same compliance and a common conduit however one unit has an increased resistance; thus airflow to the obstructed alveoli is reduced and airflow to the normal unit is increased

Situation C: the compliance of an alveoli unit is decreased by 50% (due to fibrosis-stiff); the two units would fill with the same time course but the unit with reduced compliance would lower lung volume (half compared to the normal unit)

48
Q

How does yawning and sighing affect lung airflow?

A
  • they increase dynamic compliance by increasing surfactant layer during the increase tidal breath
  • thus allow the lung to distend and recoil easily for airflow
49
Q

Alveoli supplied by airways with increased total airway resistance have long time constants. What is the significance of sighs and yawns?

A
  • takes longer to fill
  • very common in small airway disease/obstruction
  • pt adjust breathing to move as much air as possible to allowing changes in FRC

sighs and yawns help to increase dynamic compliance by restoring the surfactant layer during the increase tidal breath

50
Q

What’s the mechanism for expiratory flow limitation and dynamic airway compression?

A

no matter how hard you try, the expiratory flow continues to decrease as lung volume decreases and the expiratory flow rate occurs at a relatively modest level of effort

51
Q

Why is expiratory flow limited?

A

the floppy tubes that do not have any cartilage to keep them open and as a result when the pressure outside the airway exceeds the pressure in those tubes they will close off and whatever air is trapped will stay in the lung

52
Q

How and when expiratory flow occurs is important in various disease states such as COPD (Chronic Obstructive Pulmonary Disease)?

A

Normal conditions (collapse near tubes with cartilage; dynamic airway compression)

Disease state (collapse near smaller airways devoid of cartilage; premature airway closure)

lung diseased states: smaller airways closer to the alveoli will begin to trap large amounts of air allowing breathes at higher lung volumes

53
Q

Where in the respiratory cycle is forced vital capacity maneuver performed?

A

at the start of exhalation

54
Q

With a forced exhalation, what is the driving pressure for expiratory gas flow?

A

the sum of the elastic recoil pressure and the pleural pressure

55
Q

Normally airway compression is near what kind of tubes?

A

tubes with cartilage

56
Q

In obstructive lung diseases like COPD where does airway compression occur?

A

they occur in floppy tubes; their airway has so much trouble generating force to bring the air out

the equal pressure point is dynamic; lung volume decreases and elastic recoil pressure decreases the equal pressure point moving it closer to the alveoli, occuring in smaller airway without cartilage

Airway readily collapse.

57
Q

What is the difference between trapped air and dead space air?

A
  • trapped air is within the alveoli
  • the air that never participates in gas exchange and stays in the tubes that are conduits for bringing air to the respiratory zone for gas exchange
58
Q

What type of flow produces sound?

A
  • turbulent flow

- cough involves turbulent airflow

59
Q

What happens to tracheal dimensions and air velocity during cough?

A

During cough, the non-cartilaginous posterior membranous region of the trachea is compressed causing tracheal diameter to narrow.

The turbulent airflow at the site of compression is the sound that we refer to as “cough”.

Air velocity is faster.

60
Q

What is responsible for the “crackles” on auscultation of patients with lung disease?

A

premature airway closure which can be caused by

  • mucus, edema, inflammation, fluid in airway or any mechanism responsible for airway narrowing or compression
  • loss of elastic recoil as observed in patients with emphysema
61
Q

What are characteristics of premature airway closure?

A
  • air trapping in the alveoli causes increased lung volume (RV and FRC)
  • initially the extra volume helps to offset the resistance to airflow caused by mucus and inflammation in the airway (increase caliber and elastic recoil)
  • as disease progress, the increased inflammation/mucus production causes limitation in flow rate and maximal expiratory rates decrease
62
Q

COPD is a combination of what two conditions?

A

bronchitis and emphysema

63
Q

What is the main driving force in the lung for moving air out?

A

static elastic recoil pressures

64
Q

Alterations in the expiratory flow volume relationship can be caused by?

A
  • fluctuations in total airway resistance and distribution of resistance along the airways
  • airways losing structural integrity
  • changes in static elastic recoil pressures
  • airway closures occuring at much higher volume in individuals with obstructive pulmonary disease
65
Q

What is the work of breathing associated with?

A
  • energy used by the respiratory musculature to generate a force for the movement of air between the environment and lungs
  • with the force required to overcome both mechanical properties of the lung and chest wall (elastic and flow resistive forces)
  • when babies are born prematurely they often do not have surfactant resulting in huge increase in energy expenditure for overcoming the surface tension in the lungs; they can exhaust themselves and go into respiratory failure
66
Q

When the work of breathing is not achieved, what happens?

A
  • changes in muscle strength (weakness) results in fatigue of the diaphragm- respiratory failure results
  • the respiratory system can no longer supply oxygen and eliminate CO2; gas exchange is insufficient to meet metabolic demand
67
Q

Describe work of breathing in mathematical terms.

A

W= pressure X change in volume

lung tissue and chest wall have impact on how much energy yo uexpand to move your thorax and expand alveoli to receive the air

68
Q

What are the elastic and resistive components for the work of breathing?

A

elastic:
- overcoming the recoil of the chest wall and lung parenchyma
- work to overcome the surface tension

resistive:
- tissue (lung) and airway resistance

69
Q

What is the direct way to measure work?

A
  • there is NO direct way to measure work

- analysis of pressure volume loops are used to get an indication of the energy expenditure for breathing

70
Q

Look at pressure volume graph

A

know the boundaries!!!!

71
Q

How does restrictive lung disease (reduced compliance) such as pulmonary fibrosis or obesity change the shape of the pressure volume curves?

A
  • increased work to lift the excess weight and expand the thorax to move the air in
  • increased total mechanical work to overcome elastic resistance
72
Q

What occurs in patients with chronic COPD?

A

predominantly live sedentary; they have barrel chest, diaphragm is now flat due to retention of the air

73
Q

How does asthma or bronchitis change the shape of the pressure volume curves?

A

there is increased expiratory workload due the increased airway resistance

74
Q

T/F There is hugh increase in the amount of work for either restrictive or obstructive pulmonary disease.

A

True

-most of the patients will receive oxygen supplement to help maintain gas exchange

75
Q

Individuals in good health and during disease states will adopt what pattern of breathing?

A

Patients will try to breathe in a manner that requires the least amount of work.

76
Q

What is the breathing pattern associated with pulmonary fibrosis?

A

shallow/rapid pattern

77
Q

What is the breathing pattern associated with obstructive pulmonary disease?

A

their trying to take deep, slow breaths to overcome the resistance and get the best possible oxygenation to carry out gas exchange

78
Q

What is the normal respiratory rate?

A

12-18 breaths/min

79
Q

What is the oxygen cost of total body oxygen uptake for quiet breathing?

A

5%

  • increases to 30% with exercise
  • in disease states, the work of breathing is high and likely the limiting factor in exercise (anything above their baseline will cause them to do more work)
80
Q

Bronchitis, emphysema, asthma is obstructive.

A

Fibrosis is restrictive.

CSF3 Exam 2 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions