Gas Exchange and O2 Transport

Question 1

Surfactant is a lipid protein complex that is produced by…

Answer 1

Type II alveolar cells.
surfactant contains hydrophobic and hydrophilic regions that allow it to incorporate into air-liquid interface

Question 2

Surfactant reduces ___ to a greater extent in smaller v. larger alveoli and prevents ___

Answer 2

surface tension; atelectasis = alveolar collapse

Question 3

Surfactant reduces ___ which increases lung compliance and reduces ___

Answer 3

surface tension; inspiratory work

Question 4

Surfactant reduces ___ which also reduces ___ in the alveoli

Answer 4

surface tension; fluid accumulation

Question 5

Elastic Properties of the Lung

Answer 5

Inward elastic recoil facilitates exhalation

Question 6

Elastic Properties of the Chest Wall

Answer 6

Outward elastic recoil facilitates inspiration

Question 7

At volumes above functional residual capacity, the net recoil pressure of the respiratory system factors…

Answer 7

a decrease in lung volume
maintained by the actions of the muscles of inspiration

Question 8

At lung volumes below functional residual capacity, the net recoil pressure of the respiratory system favors…

Answer 8

an increase in lung volume
maintained by the actions of the muscles of expiration

Question 9

If intrapleural pressure is raised to atmospheric pressure (during puncture pneumothorax) the unopposed lung tissue will recoil ___ while the opposed chest wall will spring ___

Answer 9

inward; outward
This results in a collapsed lung

Question 10

During a pneumothorax, the intrapleural pressure becomes the same as atmospheric pressure. as a result…

Answer 10

the lung collapses inward and the chest wall springs outward

Question 11

Gas exchange at the capillaries occurs by

Answer 11

passive diffusion

Question 12

Typical dry air contains ___ nitrogen and ___ oxygen and negligible amounts of CO2 and other gases. Combined, they exert the barometric pressure, which at sea level is 760mmHg.

Answer 12

79%; 21%

Question 13

the partial pressure exerted by a gas is

Answer 13

directly proportional to the percentage of that gas in the total air mixture

Question 14

Dalton’s Law

Answer 14

Px = Pb * Fx

Question 15

Like any gas, water vapor exerts a partial pressure. At body temperature, the partial pressure of H2O vapor is

Answer 15

47mmHg
humidification of inspired air effectively dilutes the partial pressure of other inspired gases by 47mmHg

Question 16

PIO2 =

Answer 16

(Pb - Ph20) * FO2
Ph2o = 47mmHg
FO2 = 21%

Question 17

end tidal PO2 and PCO2 are good measures of

Answer 17

alveolar PAO2 and PACO2
towards the end of expiration, the air expired is alveolar air

Question 18

PAO2 = PIO2 - PACO2 only works if…

Answer 18

O2 consumption = CO2 production

Question 19

For a mixed diet, RQ is ___.
CO2 production =___ of O2 consumption

Answer 19

0.8; 80%

Question 20

Alveolar Gas Equation

Answer 20

PAO2 = PIO2 - (PACO2/RQ)

Question 21

an ___ relationship exists between PACO2 and alveolar ventilation

Answer 21

inverse

Question 22

if ventilation doubles, the PACO2 will be ___ by ___

Answer 22

reduced by half

Question 23

Gas Transfer across pulmonary capillaries

Answer 23

O2 partial pressure gradient from alveoli to blood = 60mmHg (100–>40)
CO2 partial pressure gradient from blood to alveoli = 6mmHg (46–>40)

Question 24

Gas Transfer across Systemic Capillaries

Answer 24

O2 partial pressure gradient from blood to tissue cell = 60mmHg (100–>40)
CO2 partial pressure gradient from tissue cell to blood = 6mmHg (46–>40)

Question 25

Rate of Gas Exchange Across Alveolar Membrane is dependent upon 4 things:

Answer 25

1. Partial pressure gradients
2. Surface area for diffusion: increase with exercise and decreases with emphysema and atelectasis
3. solubility of gases
4. thickness of alveolar membrane

Question 26

Pneumonia

Answer 26

inflammatory fluid accumulation within alveoli

Question 27

Pulmonary fibrosis

Answer 27

chronic airway irritation replaces lung tissues with fibrous tissue

Question 28

Pulmonary Edema

Answer 28

increase in vascular permeability or pulmonary pressure (congestive heart failure), increases interstitial fluid