DSA - Lung Volumes & Capacities Flashcards
The goal of respiration is to get air from the mouth/nose to the ________.
Alveolus
What is the physiologic unit of the lung?
Alveolar-Capillary Unit
This is the amount of air inspired or expired in a single breath.
Tidal Volume (VT)
Tidal Volume varies under circumstances, for example it (INCREASES/DECREASES) during aerobic exercise.
Increases
Normal resting Tidal Volume is ________.
500 ml
This is the volume of air that cannot be forced out, not matter how hard one tries.
Residual Volume (RV)
When you get the wind knocked out of you, that means you were forced into ________ ________.
Residual Volume
Residual Volume cannot be determined by…
Spirometry
This is the additional volume that can be inhaled greater than the Tidal Volume. Considered the gap between inspiration during Tidal Volume and maximal inspiration.
Inspiratory Reserve Volume (IRV)
This is the additional volume that can be exhaled greater than Tidal Volume. This does NOT include Residual Volume.
Expiratory Reserve Volume (ERV)
Expiratory Reserve Volume requires activation of _________ _________ (i.e., active respiration).
Expiratory Muscles
This is the maximal volume to which lungs can be expanded with greatest effort. This cannot be measured by spirometry.
Total Lung Capacity (TLC)
What are the 3 possible equations for Total Lung Capacity?
TLC = IC + FRC
TLC = VC + RV
TLC = ERV + RV + IRV + VT
This is the amount of air that remains in the lungs following a normal expiration. This cannot be measured by spirometry.
Functional Residual Capacity (FRC)
What is the equation for Functional Residual Capacity?
FRC = ERV + RV
This helps prevent collapse of lungs, reduces workload, and dilutes toxic inhaled gases.
Functional Residual Capacity
This is the amount of air that can be maximally inspired following a maximal expiration.
Vital Capacity (VC)
What is the equation for Vital Capacity?
VC = IRV + VT + ERV
This is influenced by posture, ability of diaphragm to contract/relax, strength of respiratory muscles, thoracic wall expansibility, resistance to air flow, lung elasticity, and disease.
Vital Capacity
This is the capacity of air that can be maximally inspired following a normal exhale.
Inspiratory Exhale (IC)
What is the equation for Inspiratory Capacity?
IC = VT + IRV
What are the main influences on lung volumes?
Body size Age Posture Sex Ethnicity Obesity Other pulmonary disease
What increases or decreases with age?
Decreases = Forced Vital Capacity (FVC) Increases = Functional Residual Capacity (FRC) Increases = Residual Volume (RV)
Posture causes a reduced ________ when supine.
FRC (Functional Residual Capacity)
With the exception of _______ ______, obesity causes a reduction in all static lung volumes, particularly ________ ________ ________, and so ________.
Tidal Volume (VT)
Expiratory Reserve Volume (ERV)
FRC (Functional Residual Capacity)
How can Residual Volume be measured?
Helium (He) Dilution
Describe how the Helium Dilution test works for Residual Volume.
You inhale a known concentration (C1) of Helium, which is insoluble in blood, from a known volume (V1). The change in concentration (C2) due to the inhalation allows us to determine V2, which is equal to FRC.
Describe the Body Plethysmography test for Residual Volume.
You are enclosed in a rigid box and breath against a shutter. The pressure in the lungs change, and the pressure in the box changes proportionally in the opposite direction. This is calculated via Boyle’s Law (P1V1 = P2V2).
Describe the Nitrogen-Washout Technique for Residual Volume.
It determines FRC. The individual breaths 100% O2 through a one-way valve, and all expired gas is collected and monitored until N2 reaches zero. Total volume of all gas expired is determined, and multiplied by % of N2 in mixed expired air (80%).
