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Respratory system Flashcards

1
Q

how do lungs adhere to chest wall?

A

adhered by intrapleural fluid

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2
Q

what kind of pressure is generated in the intrapleural space because of the difference in elastic recoil between chest wall and lungs?

A

negative pressure is generated relative to atmospheric pressure

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3
Q

what is transpulmonary pressure?

A

the pressure difference between the alveoli and pleural cavity

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4
Q

what is the change in P(ip) during inspiration?

A

P(ip) changes from -4mmHg to -7mmHg

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5
Q

what happens to P(alv) in mid-inspiration?

A

P(alv) changes from 0 to -1mmHg

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6
Q

what is the change in P(tp) during inspiration?

A

P(tp) changes from 4 to 7mmHg

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7
Q

what is P(alv) at the end of inspiration?

A

P(alv) = 0mmHg

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8
Q

what is the primary cause of expiration? and how does this cause air to move out of lungs?

A

expiration is a passive process and occurs via elastic recoil of the lungs, shrinking thorax and thus increasing pressure so air moves out of lungs

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9
Q

what is alveolar volume? (and its value in mL)

A

alveolar volume = tidal volume - anatomic dead space

= 500-150 = 350ml

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10
Q

what is alveolar dead space?

A

part of alveolar volume in alveoli which are inadequately perfused with blood

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11
Q

what is physiological deadspace?

A

physiological dead space = anatomical deadspace + alveolar deadspace

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12
Q

minute ventilation eqauation

A

minute ventilation = tidal volume x frequency of breathing

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13
Q

dead space ventilation equation

A

deadspace ventilation = deadspace x frequency of breathing

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14
Q

alveolar ventilation equation

A

alveolar ventilation= (tidal volume - deadspace) x frequency of breathing

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15
Q

effect of deep slow breathing on alveolar ventilation and dead space

A

deep slow breathing:

  • dead space ventilation decreases
  • alveolar ventilation increases overall
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16
Q

effect of breathing through snorkel on alveolar ventilation and deadspace

A

breathing through snorkel:

  • increase in deadspace, due to volume of snorkel itself
  • minute ventilation increases
  • alveolar ventilation remains the same
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17
Q

effect of fast and shallow breathing on alveolar ventilation and deadspace

A

fast and shallow breathing:

  • minute ventilation decreases
  • deadspace ventilation increases
  • no alveolar ventilation occurs
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18
Q

how is lung compliance measured?

A

measured by the change in volume for a given change in pressure

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19
Q

disadvantages if a highly compliant lung?

A
  • reduced elastic recoil
  • inefficient passive recoil of lungs
  • expiratory muscle activity may be required even in quiet breathing
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20
Q

advantages of a highly compliant lung?

A
  • easy to inflate the lung

- little respiratory muscle activity required

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21
Q

what causes emphysema?

A

destruction of alveoli, alveoli with large air spaces

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22
Q

what characterizes emphysema?

A
  • high compliance of lungs
  • little elastic recoil
  • lungs tend to remain inflated
  • exploratory muscle activity is required to deflate the lungs
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23
Q

disadvantages of low compliant lung

A
  • difficult to inflate the lung

- string inspiratory muscle activity required

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24
Q

advantages of low compliant lung

A
  • elastic recoil of the lung is high and can recoil passively during expiration
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25
how does a patient with a restrictive lung disease tend to breathe?
- a patient with a restrictive lung disease will breathe shallow and rapidly in order to maintain sufficient alveolar ventilation
26
characteristics of pulmonary fibrosis
- low compliance of lung - alveolar wall is stiff - inspiration is harder, inspiratory muscles have to work harder - small lung volumes are achieved
27
2 determinants of lung compliance and elastic recoil
- elastic elements in alveolar interstitium (25%) | - surface tension (75%)
28
how does surface tension increase the risk of alveolar collapse?
- water molecules on the alveolar wall are moe attracted to each other than to the air - as alveoli inflate, distance between water molecues and their strength increases - thus increasing likelihood of collapse
29
what produces surfactant?
type 2 alveolar cells
30
how does surfactant reduce surface tension and increase lung compliance?
- surfactant acts as a detergent | - forms a monolayer between water and air, reduces the interaction between water molecules
31
what is respiratory distress syndrome?
- babies born before 35 weeks can't synthesize surfactant as their type 2 alveolar cells arent mature enough - the work required to overcome alveoli surface tension is too high, and lungs collapse
32
what is airflow dependant on?
the pressure gradient divided by airway resistance
33
3 major determinants of airway resistance
- viscosity if air - length - diameter/radius
34
where is the major site of airway resistance?
major site of airway resistance is in medium-sized bronchi - bronchioles
35
what is lateral (radial) traction?
- as the lungs expand, transpulmonary pressure exerts a force on the airways pulling them open - elastic tissues outside airways link to surrounding tissue
36
what type of breathing increases the dilating effect of lateral traction?
big deep breaths/inspiring large volumes of air (airways resistance is reduced)
37
what type of breathing reduces the dilating effect of lateral traction?
during the inspiration of small volumes of air (airway resistance is increased)
38
why is lateral traction greatly reduced during expiration?
lateral traction is reduced during expiration as resistance to airflow is higher
39
what 2 chemical factors affect airway resistance (decrease radius)?
- blockage by mucus or infection - local inflammatory chemical mediators (histamines, leukotrienes) causing smooth muscle to contract = bronchoconstriction
40
what neural factors affect bronchoconstriction?
stimulation of parasympathetic nerves to airways smooth muscle cause bronchoconstriction
41
what is the target/treatment for chronic bronchitis?
muscarinic ACh receptor blockers used, by targeting airway smooth muscle parasympathetic innervation
42
what is the concentration of O2 in arterial blood?
O2 conc. = 200ml/L of blood
43
what is the respiratory quotient and what does it depend on?
- RQ is the ratio of CO2 produced to 02 consumed | - RQ depends on which macro nutrient fuel source you cells are using
44
at steady state, what is the approximate RQ?
approx. 200ml C02 produced for every 250 ml 02 consumed = 0.8
45
what is Boyles law/ what does the magnitude of pressure depend on?
P1 V1 = P2 V2 | - dependant on concentration of gas and the temperature
46
what is Daltons law?
in a mixture of gases, the total pressure exerted is simply the sum of the individual gases partial pressure
47
what is the PO2 of atmospheric air at sea level
160 mmHg (0.21 x 760mmHg)
48
what is the alveolar PO2?
105mmHg
49
what is the inspired air PO2?
150mmHg
50
what is the alveolar PCO2?
40mmHg
51
what is inspired air PCO2?
approx. 0mmHg
52
3 determinants of alveolar oxygen
- how much air we breathing in from the atmosphere - how much fresh air is getting to the alveoli - how much O2 is being extracted/used by the body
53
3 determinants of alveolar CO2?
- inspired CO2 (almost always zero) - how much fresh air is getting to the alveoli - how much CO2 is being produced by the body
54
hypoventilation causes what in alveolar ventilation?
hypoventilation causes decreased alveolar ventilation
55
hyperventilation causes what in alveolar ventilation?
hyperventilation causes increased alveolar ventilation
56
(Henry's Law) the number of O2 molecules entering a liquid is proportional to..?
the 02 partial pressure in the gas
57
what happens when an equilibrium in the partial pressure of gases is reached
when equilibrium is reached, diffusion of gases ceases
58
Ficks law of diffusion
(partial P diff. x SA x diffusion coefficient)/thickness of the barrier
59
why does CO2 not diffuse faster between alveoli and capillaries than O2 even though it has a higher diffusion constant?
because CO2 has a much lower partial pressure gradient (6mmHg compared to 60mmHg for O2). therefoe not much difference in overall rate of diffusion
60
what is pulmonary oedema and how does it affect diffusion of O2?
pulmonary oedema is when fluid leaks out of pulmonary capillaries and into the interstitial space, and reduces the rate if O2 diffusion.
61
what is interstitial fibrosis and how does it affect diffusion of O2?
interstitial fibrosis is the thickening of the alveolar wall, thus increasing thickness of the barrier for gas exchange to occur, reducing rate of O2 diffusion
62
what is empysema and how does it affect the diffusion of O2?
emphysema is the destruction of alveolar walls which decreases the surface area for gas exchange and the number of pulmonary capillaries, thus reducing O2 diffusion rate

phty251 (6 decks)

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