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20 Cards in this Set

  • Front
  • Back
what is the PO2 in the aorta vs. RA? PCO2?
aorta: PO2- 100
PCO2- 40
RA: PO2- 40
PCO2- 46
what is the sequence of airways? which are involved in gas exchange?
trachea->bronchi->bronchioles->terminal bronchioles->respiratory bronchioles->alveolar ducts->alveolar sacs
gas excahnge occurs ONLY at the alveolar ducts and sacs
what composes an alveolar wall? what are some properties?
planar aggregate of capillaries; each surrounded by alveolar space; allows large SA for gas exchange with short distance for diffusion
what are alveolar type 2 cells?
make surfactant
covered in microvilli
protrude into alveolar space
partial pressue of O2, N2 in room
PO2= 160mmHg (160 Torr)
PN2= 600mmHg
b/c atmosphere in 21% O2 and 79% N2
what happens to the partial pressure of O2 and N2 when air is breathed into the lungs?
another species of gas is added: water vapor. this changes the PO2 and PN2 because their relative concentrations change
what is the partial pressure of water vapor at body temp (ie. in the airways)? how does this change PO2, PN2?
in airways: PO2=150, PN2=563
if we are at high altitude in a chamber of CO2 but remain at body temperature what happens to the vapor pressure of water?
nothing. vapor pressure of water depends ONLY on temperature
what determines the movement of gases into fluids?
gases dissolve into fluids by moving down PARTIAL PRESSURE gradients
ie. you can have gases move up a concentration gradient, dep on solubility of the gas in the 2 compartments
what can be said of the PO2 in the alveolus and capillary when at equilibrium?
the PO2 are the same (100mmHg)
# gas mol entering fluid=#gas mol leaving
how do you determine how good an exchanger is?
perfect exchanger: PAO2=PaO2
(A=alveolar gas being exhaled; a=arterial blood leaving lung)
difference between PAO2 and PaO2 is A-a difference
the larger the difference, the poorer the exchange
what determines how much gas is exchanged? (5)
1. SA
2. thickness of mbr
3. solubility of gas in mbr
4. partial pressure gradient
5. degree of matching
what is meant by degree of matching?
degree of ventilation vs. perfusion
if the are equal, ideal exchanger (minimal A-a difference)
what is dead space?
wasted ventilation
ventilation without perfusion (Po>Pi)
what happens when airways are occluded? what is an ex?
perfusion without ventilation;
R->L shunt because blood leaves without being oxygenated
no gas exchange
dangerous because wasting blood flow
what happens when one airways is obstructed?
PAO2 normal
PaO2 low
A-a difference large
what happens with a pulmonay embolus?
dead space
PAO2 higher than normal
PaO2 normal
what is PAO2?
PO2 of air coming out of mouth from alveolus
what is PaO2?
PO2 in blood leaving lungs
how does cross sectional area and resistance explain the requirement for cartilage rings in the upper airways?
large, upper airways: low cross-sectional area, high resistance, high velocity, low lateral wall pressure (Bernoulli), high rate of collapse
small, lower airways- large cross-sectional area, low resistance, low velocity, high lateral wall pressure, no need for cartilage because wont collapse