Diffusion & Perfusion Flashcards
_____ is the arterial oxygen content, which is the total concentration of O2 in blood.
CaO2
CaO2 is the arterial oxygen content, which is the _____.
total concentration of O2 in blood
For a healthy person CaO2 is about _____ or _____ O2/100 ml blood.
9.1 mM; 20.7 ml
Why isn’t very much O2 dissolved in the blood?
it’s not very soluble and it quickly binds to hemoglobin
What is the solubility coefficient?
the tendency of any molecule to dissolve in a liquid
What is the tendency of any molecule to dissolve in a liquid called?
the solubility coefficient
CO2 is about ______ more soluble in blood than O2.
20 times
How is O2 flux maximized across the alveolar membrane?
- large SA of the alveolar membrane
- thin membrane width (d)
- large O2 pressure gradient
During ______, when there is thickening of the alveolar walls (increased d), the rate of diffusion is slowed.
interstitial disease
During interstitial disease, when there is thickening of the alveolar walls (increased d), the rate of diffusion is ______.
slowed
Name 3 ways diffusion can be altered.
- interstitial disease (thickened alveolar walls)
- emphysema (decreased SA)
- changed hemoglobin concentration (polycythemia, anemia)
What does perfusion limited mean?
conditions do permit rapid equilibration of blood with alveolar air (only factor is blood flow); PO2 and PCO2 in blood exiting the pulmonary exchange area is similar to alveolar PO2 and PCO2
What does diffusion limited mean?
conditions DO NOT permit complete equilibration of alveolar air and blood; the PO2 in the blood exiting the pulmonary exchange area will be less than alveolar PO2
_____ is the blood flow of the pulmonary circulation available for gas exchange (in one minute).
Perfusion, Q,
Perfusion, Q, is _____.
the blood flow of the pulmonary circulation available for gas exchange (in one minute)
Perfusion equals the cardiac output, which for an
adult at rest is _____.
= 5 liters/ min
Perfusion equals ______, which for an adult at rest is Q = 5 liters/ min.
the cardiac output
At any given time, there is about _____ of blood in the lung, comprising 40% of the lung weight.
500 ml
At any given time, there is about 500 ml blood in the lung, comprising ____% of the lung weight.
40
What factors regulate perfusion?
- O2 tension
- chemical agents (thromboxane, prostacyclin)
- capillary recruitment
- gravity
The factor of overriding importance in governing minute to-minute regulation of the pulmonary circulation is the ______.
alveolar O2 tension, PAO2
______ causes constriction of the nearby arterioles.
Low alveolar PO2
Low alveolar PO2 ______ the nearby arterioles.
constricts
What is hypoxic pulmonary vasoconstriction?
a decrease in local blood flow in the lung to shift it to other regions
Where do thromboxane and prostacyclin come from?
arachadonic acid
______ is the most important vasoconstrictor.
Thromboxane A2
Thromboxane A2 is the most important ______.
vasoconstrictor
________ is a potent vasodilator.
Prostacyclin
Prostacyclin is a potent _______.
vasodilator
Because of _____, the pulmonary blood pressure is low at the apex of the lung.
gravity
Because of gravity, the pulmonary blood pressure is low at the _____ of the lung.
apex
What is a shunt?
blood perfusion where there is no ventilation
What is it called when there is blood perfusion where there is no ventilation?
a shunt
