Respiration: Ventilation (V), Perfusion (Q) & V/Q Relationship Flashcards
What is ventilation?
Process by which air moves in and out
of lung.
What is perfusion?
Process by which deoxygenated blood
passes through the lung and becomes oxygenated
Why is ventilation not uniformly distributed in the lungs?
Gravity
What does the term compliance refer to?
How much effort is required to stretch the lungs and chest wall
When is decreased compliance common?
In pulmonary conditions such as tuberculosis
What does resistance refer to?
Narrowing or obstruction of the airway that my reduce
airflow.
When is increased resistance common?
In pulmonary conditions such as asthma and COPD
What is anatomical dead space?
Volume of gas during each breath that fills the conducting airways.
What is physiological dead space?
Total volume of gas in each breath that does not participate in gas exchange, e.g., alveoli that are perfused but not ventilated.
How do you calculate the V/Q ratio for the entire lung?
Alveolar ventilation / cardiac output
What is the average V/Q ratio of the entire lung for a healthy individual?
0.8-1.2
What is arterial hypoxemia?
When the partial pressure of arterial o2 is less than 80mmHg
What is an anatomical shunt?
The blood taken in by the pulmonary artery doesn’t become deoxygenated. This means the blood being delivered to rest of body is dilated, effecting PO2
When are anatomical shunts common?
In babies at a cardiac level
What is a physiological shunt?
When the ventilation to the lung is absent, effecting the po2 leaving the lung. The alveolar sac is blocked
