True or False
The lung region with the highest PO2 is the base.
False (apex)
When V/Q = ∞, there is ventilation with zero perfusion, which means air reaches alveoli, but no blood flows. This is called _________.
dead space
Which lung region has the lowest V/Q ratio?
The base (Zone 3).
V/Q mismatch is the most common cause of hypoxemia in clinical scenarios like COPD, asthma, and pulmonary embolism.
True.
V/Q mismatch is typically characterized by an increased _________ gradient.
alveolar-arterial (A-a)
What does an airway obstruction (ex: mucus plug) cause?
Low V/Q (Shunt)
A pulmonary embolism causes a low V/Q also known as dead space.
False (high V/Q also known as dead space)
When V/Q = 0), there is perfusion with zero ventilation, which means blood passes alveoli without picking up O2. This is called _______.
a shunt
In hypoxic pulmonary vasoconstriction, the lung tries to correct a _______ V/Q by constricting blood vessels in that area to _______ Q and redirect blood to better-ventilated areas.
low, reduce
Ventilation-perfusion (V/Q) ratio is a measure of the relationship between the amount of air entering the alveoli (V) and the amount of blood flowing through the capillaries surrounding the alveoli in the lungs (Q).
True
What happens to PaO2 and PaCO2 in a low V/Q unit?
PaO2 falls, PaCO2 rises
Does a pulmonary shunt respond to 100% oxygen?
No (or very little)