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Respiratory Exam 1 > Alveolar Gas Exchange > Flashcards

Alveolar Gas Exchange Flashcards

1
Q

blood entering the pulmonary capillary is (what type of blood)

A
  • mixed venous
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2
Q

blood leaving the pulmonary capillary is

A
  • arterial
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3
Q

rate of movement of gas through tissue over time directly proportional to

A
  • permeability
  • partial pressure gradient
  • tissue surface area
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4
Q

rate of movement of gas through tissue over time inversely proportional to

A
  • tissue thickness
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5
Q

gas permeability is directly proportional to

A
  • solubility of gas in barrier tissue and blood
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6
Q

gas permeability is inversely proportional to

A
  • molecular weight
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7
Q

which gas is more permeable in the lung (O2 or CO2)

A
  • CO2
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8
Q

alveolar type I epithelial cell and pulmonary microvascular endothelial cell share

A
  • opposite sides of a common basement membrane
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9
Q

which gradient is higher for O2 and CO2

A
  • O2 but CO2 is more soluble
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10
Q

alveoli are richly supplied with

A
  • capillaries
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11
Q

the diffusing distance from oxygen extends from

A
  • alveolus to hemoglobins molecules within erythrocytes
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12
Q

what does the diffusion barrier consist of?

A
  • alveolar air
  • surfactant and fluid layer
  • alveolar type I cell
  • lung interstitial
  • endothelial cell
  • blood plasma
  • RBC hemoglobin
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13
Q

what is the thickness of the blood-gas barrier?

A
  • miniscule
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14
Q

what drives diffusion across the blood gas barrier

A
  • differences in partial pressures
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15
Q

which gas molecules can exert a partial pressure

A
  • free, unbound gas molecules
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16
Q

how long does it take for an erythrocyte to traverse the capillary across the width of an alveolus

A
  • about .75 seconds
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17
Q

how long does it take O2 and CO2 to equilibrate across the blood gas barrier

what does this mean?

A
  • about .25 seconds

- there is reserve time for additional gas exchange

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18
Q

does O2 bound to Hb exert a partial pressure?

A
  • no
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19
Q

in what forms can oxygen exist in the blood

what form has greater existence

A
  • dissolved O2
  • O2 bound to hemoglobin
  • O2 bound to hemoglobin
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20
Q

N2O permeability

does it bind to hemoglobin?

considered in partial pressure determination

A
  • highly permeable
  • it does not.

considered in partial pressure determination

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21
Q

CO permeability

does it bind to hemoglobin

considered in partial pressure determination?

A
  • low permeability
  • it does. almost irreversibly.
  • takes it out of partial pressure determination
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22
Q

the greater the perfusion

A
  • the greater the uptake of gas by the lung
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23
Q

what is a perfusion limitation

A
  • blood leaves pulmonary capillary fully equilibrated with a gas
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24
Q

what is diffusion limitation

A
  • when blood leaves pulmonary capillary before it is equilibrated with a gas
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25
which gasses are perfusion limited under normal conditions?
- N2O - O2 - CO2
26
which gasses are diffusion limited under normal conditions
- CO
27
when can O2 or CO2 become diffusion limited
- heavy exercise in elite athletes - high altitudes - severe pulmonary disease
28
approximately half of the overall resistance to O2 loading of the alveolar capillary blood due to
- kinetics of Hb-O2 binding reaction
29
result of pulmonary fibrosis effect on O2 equilibrium
- thickened interstitium due to collagen deposition | - increases time for O2 equilibration
30
result of pulmonary edema effect on O2 equilibrium
- interstitiium thickened by excess fluid | - increase O2 equilibration time
31
conditions that impair diffusion at rest what about exertion
- may allow O2 equilibration | - will probably cause disequilibration
32
high hydrostatic pressure favors
- fluid out of capillary into intersitium | - does not push out protein
33
as you go down the capillary, what will happen with the colloid osmotic pressure
- as fluid leaves the vessel, colloid oncotic pressure increases down vessel length - will draw water back into the capillary at the pulmonary vein
34
pulmonary edema on capillary permeability
- increases capillary permeability
35
pulmonary edema on capillary hydrostatic pressure
- increases capillary hydrostatic pressure
36
pulmonary edema on plasma oncotic pressure
- decreases plasma oncotic pressure
37
how can we measure how well diffusion is happening?
- diffusion capacity of the lung for CO
38
factors affecting diffusion of CO across the lung
- surface area - permeability of blood-gas barrier - Hb status - body position - exercise
39
what parts of Hb status would affect CO diffusion across the lung?
- anything that reduces Hb - anemia - carboxy-Hb (smoking) - oxyhemoglobin (O2 therapy)
40
2/3 of O2 consumed goes to
- skeletal muscle - brain - liver
41
slope of Hb-O2 dissociation curve
- sigmoid
42
hemoglobin is nearly saturated with O2 at partial pressures as low as
- 70 mmHg
43
large amount of O2 are ________ in response to small decrements in PO2 in the ___________
- unloaded | - metabolizing tissues
44
affinity of Hb for O2 is modified by
- pH - pCO2 - temperature - 2,3 DPG (glycolytic product)
45
what is the Bohr effect
- low pH and CO2 shifting Hb-O2 curve to the right
46
rightward shift means Hb affinity for O2 is _______ at a given PO2
- lower
47
CO2 is carried in what forms which one mainly
- dissolved gas - bound to Hb as carbamino Hb - bicarbonate (HCO3-) (mainly)
48
bicarbonate reaction
- CO2 + H2O -> H2CO3 -> HCO3 + H+
49
what is the chloride shift
- exchange of HCO3- for Cl- that occurs in red blood cells | - how bicarb gets into the plasma
50
protons generated in the bicarbonate reaction help to
- dissociate O2 from Hb so it can be delivered to the tissues
51
high PO2 in the lungs helps to what is this known as
- remove CO2 to deliver to alveolus | - Haldane effect
52
CO2 dissociation curve
- much more linear over a wide range
53
what happens to deoxygenated hemoglobin
- it picks up CO2
54
CO2 is directly proportion to ______ ventilation
- lung ventilation
55
result of hypoventilation on alveolar PCO2
- alveolar PCO2 will increase
56
result of hyperventilation of alveolar PCO2
- alveolar PCO2 will decrease
57
what does pulse oximetry provide us
- pulse | - Hb saturation
58
oxygenated hemoglobin absorbs which light which light passes
- infrared light | - red light passes
59
deoxygenated hemoglobin absorbs which light which light passes
- absorbs red light | - infrared light passes
60
what does pulse oximetry measure
- ratios of red and infrared light
61
when would hemoglobin not bind to oxygen normally
- CO poisoning | - heme iron in ferric instead of ferrous state

Respiratory Exam 1 (27 decks)

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