Ventilation Flashcards
The volume of gas inspired or expired in a single respiratory cycle
tidal volume
the maximum volume of gas that can be inspired starting at the end of normal inspiration
inspiratory reserve volume
the maximum volume of gas that can be expired starting from the end of a normal expiration
expiratory reserve volume
the volume of gas that remains in the lungs after a maximum expiration
residual volume
the total amount of gas in the lungs at the end of a maximum inspiration (the sum of all four lung volumes)
total lung capacity
the maximum volume of gas that can be expired after a maximum inspiration
vital capacity
the maximum amount of gas that can be inspired starting from FRC
inspiratory capacity
the amount of gas in the lungs at the end of a normal expiration
functional residual capacity
Three types of dead space:
anatomic dead space
alveolar dead space
physiologic dead space
within each tidal volume, there is a volume of gas that does not participate in gas exchange; it is nonfunctional air in terms of diffusion of O2 or CO2
anatomic dead space
volume of air contained within the nose, sinuses, pharynx, larynx, and conducting airways
alveolar dead space
volume of air contained within non-perfused alveoli
physiologic dead space
functional measurement bc it is the sum of anatomic dead space and alveolar dead space
Turbulant Flow
disorganized flow, requiring greater pressure v laminar flow
Transitional Flow
mixture of turbulant and laminar flow
Laminar flow
parabolic profile and smooth flow
Ohm’s Law:
Pressure = Flow * Resistance
V = P/R
Poiseullie’s Equation
solves for airflow
Poiseullie’s Equation Take Home message for increasing airflow
increase pressure
increase radius (sympathetics)
reduce viscosity
reduce length
Airway Resistance:
when total airway cross sectional area increases
airway resistance decreases
at large lung volumes…
the airways widen and the resistance to airflow decreases
at lower lung volumes…
the airways become narrow, and airflow resistance increases
at very low lung volumes,
the small airways might close completely, especially at the bottom of the lung
obstructive lung diseases
increase in airway resistance
ex: asthma, bronchitis and emphysema
Obstructive lung diseases:
emphysema
inspiration is easier due to loss of elastin/collagen
expiration is harder due to airway collapse which obstructs air flow
loss of radial traction