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RC Test 2 > B4.023 - Mechanisms of Ventilation > Flashcards

B4.023 - Mechanisms of Ventilation Flashcards

1
Q

what are the 4 components of respiration

A

Ventilation

Alveolo-capillary diffusion

blood gas transport

capillary-cell diffusion

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2
Q

for ventilation to occur what 2 things have to happen

A
  1. create airflow 2. stretch the lungs
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3
Q

what is PTp

A

Transpleual pressure =Palv - Ppl ~ change in volume/compliance

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4
Q

what is PPl

A

pressure in pleural space, usually negative to help lungs expand

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5
Q

what are the opposing tendencies of thorax and lungs

A

thorax tends to expand lungs tend to recoil these opposing forces create a subatmospheric pressure in thoracic cavity

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6
Q

what is transpulmonary pressure

A

pressure needed to keep lungs open

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7
Q

what do each of these lines represent

A
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8
Q

why does pleural pressure drop as you inspire

A

because the lungs are opening and volume is increasing, and tendency of lungs to recoil is increasing dropping pleural pressure

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9
Q

what is happening in the red

A

forced exhalation and inhalation

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10
Q

what does this represent in a lung

A

increased resistance

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11
Q

what does this represent in the lung

A

decreased compliance

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12
Q

in any given lung a higher volume means what

A

you have a higher PTp

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13
Q

higher flow means what

A

higher resistance

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14
Q

to have an increase in flow what else has to increase

A

difference between Patm and Palv has to increase

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15
Q

at all times in the lung PB - Ppl = what

A

(PB-Palv) + (Palv-Ppl)

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16
Q

what happens when you breath in and then pause mid breath

A

Ppl drops, flow stops, volume stays the same, Palv is 0

PTP STAYS THE SAME!!!

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17
Q

What happens to lung pressures in the case of a stiff lung

A

flow stays the same

Ppl has to decrease a lot more

higher Ptp

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18
Q

what happens to lung pressures in the case of increased airway resistance

A

alveolar and plaural pressures drop so Ptp stays the same

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19
Q

how do you measure compliance

A

Pulmonary compliance = change in lung volume / change in Ptp

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20
Q

what is the change in lung compliance if Ppl changes to -10

A

compliance goes up

from 2500/10 –> 2500/5

lung is easy to inflate but hard to compress

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21
Q

what does the slope of this line represent

A

compliance

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22
Q

what are 2 main factors of elastic properties of lung

A

elastic fibers in lung - tether and stretching

surface tension

23
Q

in the setting of emphysema what happens

A

you lose elastic fibers which make the lungs more compliant but harder to deflate

rubber band –> celofane bage

24
Q

what is laplaces law

A

pressure needed to keep alveoli open is inversely related to radius of alveoli

P=2ST/radius

25
Q

what happens if two differently sized alveoli are connected

A

the smaller will collapse into the larger one

as lung volume becomes smaller during forced expiration. the tendency of alveoli to collapse increases

26
Q

what is surfactant

A

a lipoprotein that acts as a detergent, lowers ST lowering pressure needed to keep alvioli open

27
Q

what happens to effective concenatration of surfactant as radius decreases

A

it increases, works better in smaller alveoli

28
Q

what happens if there is insufficient surfactant?

A
  1. decreased compliance
  2. atelectasis
  3. pulmonary edema
29
Q

where is the site of highest airway resistance

A

nose

30
Q

what accounts for 10% of total resistance in airways

A

airways <1mm diameter

31
Q

how do you calculate total airway resistance

A

PB-Palv/airflow

32
Q

indentify each component of this graph

A
33
Q

what is TV

A

tidal volume, how you breath normally

34
Q

what is TLC

A

max inspiration volume

35
Q

what is IRV

A

inspiratory reserve volume, amount of air above TV you can breath in

36
Q

what is ERV

A

expiratory reserve volume, amount of air you can exhale other than RV and under what you normally exhale (TV)

37
Q

what is RV usually in percentage

A

20%

38
Q

what is VC

A

total amount you can exhale from max inspiration except residual volume

39
Q

what is FRC

A

volume in lungs at end of normal expiration

40
Q

what is normal FEV1/FVC

A

.7-.8

41
Q

what is forced vital capacity

A

most you can exhale

42
Q

what is FEV1

A

amount you can exhale in 1 second

43
Q

What does this graph represent

A
44
Q

what do a, b, c correspond to in this graph

A

a = highest effort

b = normal

c = least effort

45
Q

what is the value of the flow volume loop

A

demostrates effort dependent and independent states of expiration

46
Q

what does effort independent mean on flow volume loops

A

no matter how hard you expire you cant change slope of line

47
Q

why cant you change the slope of effort independent portion of flow volume loops

A

greater flow = greater resistance

the alveoli sustains increased pressure due to diaphragm relaxation, with maximal effort youre contracting lungs fast as possible and the pressure is increasing, so is pleural pressure. This intra thoracic pressure increase narrows alveolar pressures and increases resistance

48
Q

what is dynamic airway compression

A

inherent aspect of lungs that slows flow and increases resistance

responsible for effort independent portion of volume flow loop

When you forcefully contract lungs to exhale the alveolar and pleural pressures both increase significantly, this increases pressure on airways and increases resistance

49
Q

what do lines a and b respresent

A

a. normal airway resistance
b. moderate increase in airway resistance

50
Q

what does line c represent here

A

severe increase in resistance

Note: increased residual volume bc you cant exhale as much as you normally would

51
Q

what are some mechanisms of increased airway resistance (pathology)

A

Contraction of BSM: Asthsma

narrowing of airway lumen: chronic bronchitis

loss of elastic recoil : ephysema

52
Q

equation for resistance

A

resistance = PB-Palv/airflow

53
Q

equation for compliance

A

compliance = change in volume/change in Palv - PPl

RC Test 2 (19 decks)

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