Pulmonary gas exchange Flashcards

1
Q

atmospheric pressure at sea level is __

A

760 mmHg

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2
Q

addition of water causes the partial pressure of other gases to __

A

decrease

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3
Q

Increasing alveolar ventilation will increase __

A

PAO2

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3
Q

The rate of gas diffusion across the respiratory membrane depends on

A
  1. Difference in Partial Pressures Across the Membrane (ΔP )
  2. Solubility of Gas in Fluid (S)
  3. Cross-Sectional Area of Membrane (A)
  4. Distance of Diffusion (d)
  5. Molecular Weight of Gas (MW)
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3
Q

V=

A

ΔP x A x S/ d x √MW

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3
Q

gas exchange at the respiratory membrane depends on

A
  1. transport rate
  2. rate of alveolar ventilation
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3
Q

A tissue with high metabolic activity will have a lower __, creating a __ partial pressure
gradient

A

PO2, larger

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3
Q

CO2 is more soluble (S) than O2 so CO2 diffuses __

A

more rapidly

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3
Q

If more pulmonary capillaries are recruited, as in exercise, the surface area (A) available for diffusion __

A

increases

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3
Q

If the thickness of the diffusion barrier increases (d), such as with Pulmonary Fibrosis or Edema, this __

A

decreases diffusion

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3
Q

Components of Respiratory Membrane

A
  1. Surfactant
  2. Alveolar Epithelium
  3. Alveolar Basement Membrane
  4. Interstitial Space
  5. Endothelial Basement Membrane
  6. Capillary Endothelium
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3
Q

Average width of respiratory membrane is __

A

0.6 μm

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3
Q

Under normal conditions, O2 transport into pulmonary
capillaries is __ limited

A

perfusion

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3
Q

O2 transport with other conditions (fibrosis, etc) is __ limited

A

diffusion

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3
Q

diffusing capacity of the lung measures the respiratory membrane’s functional __

A

integrity

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3
Q

diffusing capacity of the lung measures the amount of gas entering __ per unit time

A

pulmonary blood

3
Q

DLCO2 cannot be calculated because of __

A

rapid diffusion and O2 binds to hemoglobin

3
Q

Carbon monoxide is ideal for DL since it is __ limited

A

diffusion

3
Q

What could an abnormally low DLCO test indicate?

A
  1. thickening of barrier
  2. decreased surface area
  3. decreased uptake
3
Q

thickening of barrier can be due to __

A

-interstitial edema or fibrosis

3
Q

decreased surface area can be due to __

A

-emphysema
-low CO
-tumors
-ventilation- perfusion mismatch

3
Q

decreased uptake can be due to __

A

-anemia
-decreased BV in pulmonary capillaries

3
Q

large difference between PAO2 and PaO2 indicated a problem with __

A

diffusion

3
Q

You cannot easily measure __

A

PAO2

3
Q

PAO2 is predicted based on

A
  1. partial pressure of O2 inspired
  2. PaCO2
  3. ratio of CO2 produced/ O2 consumed
4
Q

Normal good estimate for a A-a gradient is

A

Age/4+4