Flashcards in Ventilation-Perfusion Relationships Deck (10):
How can the body compensate for low V in an area to maintain V/Q balance?
Hypoxic vasoconstriction- lowers Q.
What does a pulmonary embolus do to V/Q?
Dead space is created -> "infinite" V/Q
Does low V/Q (e.g. from pneumonia, edema) cause predominately hypoxia or hypercarbia?
(Hyperventilation can compensate for the hypercarbia... and CO2 has an easier time diffusing out across fluid in the alveoli?)
Does high V/Q cause predominately hypoxia or hypercarbia?
Predominately hypercarbia. (though hypoxia also occurs.)
What effect does low V/Q have on neighboring segments?
Hyperventilation -> increased ventilation to neighboring segments.
What effect does increased V/Q (dead space) have on neighboring, healthy statements?
Blood flow is increased to healthy segments.
In an upright perfusion, where in the lung are ventilation and perfusion the greatest.
Ventilation and perfusion are both greatest in the lower lungs.
In an upright person, how does V/Q ratio compare high in the lung vs. low in the lung?
V/Q is high at the top, low at the bottom.
If you have an area of high V/Q and an area of low V/Q, why do you still get hypoxemia?
Because of the shape of the hemoglobin O2-binding curve, increased V/Q won't increase arterial pO2 as much as low V/Q will lower it.