Lung Volumes Flashcards
What volume is the amt of air that can still be breathed in after normal inspiration?
Inspiratory reserve volume
What volume is the amt of air that moves into the lung with each quiet respiration?
Tidal volume
What is a normal tidal volume?
500mL
What volume is the amt of air that can still be breathed out after normal expiration?
Expiratory reserve volume?
What volume is the amt of air in lung after maximal expiration?
Residual volume
What lung volume cannot be measured on spirometry?
Residual volume
What is the inspiratory reserve volume + the tidal volume?
Inspiratory capacity
What is the residual volume + expiratory reserve volume?
Functional residual capacity
What is the functional residual capacity (in words)?
The volume of gas in the lungs remaining after normal expiration.
What is the TV + IRV + ERV?
Vital capacity
What is the vital capacity (in words)?
The maximal volume of gas that can be expired after a maximal inspiration; everything except the residual volume, which can’t be expired. It essentially is the “moveable” capacity of the lung.
What is the IRV + TV + ERV + RV?
Total lung capacity - the volume of gas present in lungs after maximal inspiration
What is dead space?
Volume of inspired air that does not take part in gas exchange
What are the components of dead space?
Anatomic dead space of conducting airways + alveolar dead space.
Where is the largest contributor of alveolar dead space?
Apex of the lung
What is the formula for dead space?
Vd = Tidal volume X (Arterial CO2-Expired CO2)/Arterial CO2
(taco paco peco paco).
What does the formula for dead space mean in words?
Dead space = Normal inspiratory volume * % of arterial CO2 that does not get diffused into the alveolus and expired.
What is the minute ventilation? (Ve)
Total volume of gas entering lungs per minute.
Vt * RR
What is the alveolar ventilation?
Volume of gas per unit time that reaches alveoli
Va = (Vt-Vd) * RR
What is the elastic recoil tendency of the lung?
To collapse inward
What is the elastic recoil tendency of the chest wall?
To spring outward
What is the point at which the inward pull of the lung is balanced by the outward pull of the chest wall?
Functional residual capacity; this is the volume of gas in lungs after normal expiration.
How does system pressure in the lungs compare to atmospheric pressure at the elastic recoil balance point?
They are equal; essentially, when you finish a normal breath, you’re at a “starting” point, or a “balance” point. This ends the airflow out of the lungs (leaving the functional residual capacity - you have to blow harder to get that out, as there is no longer a pressure gradient doing the work for you) and air does not flow in yet until negative pressure is generated by inspiratory forces.
What are the determinants of FRC?
Elastic properties of both chest wall and lungs
At FRC, what is intrapleural pressure? Why?
Negative. Prevents pneumothorax.
What is the compliance of the lung?
“Stretchiness” - change in lung volume for a given change in pressure.
How does compliance of the lung change with emphysema and aging?
Increases. More loose and stretchy.
How does compliance of the lung change with pulmonary fibrosis, pneumonia, and pulmonary edema?
Decreases. More tight and unstretchy.
