3.6.2. Respiratory System Mechanics Flashcards
Static lung mechanics - relationships between pressure and _______ of the lung
Static lung mechanics - relationships between pressure and volume of the lung
What are the four lung volumes?
Tidal Volume (TV)
Inspiratory Reserve Volume (IRV)
Expiratory Reserve Volume (ERV)
Residual Volume (RV)
What are the four lung capacities?
Inspiratory Capacity (IC)
Functional Residual Capacity (FRC)
Vital Capacity (VC)
Total Lung Capacity (TLC)
What is Tidal Volume? (Definition)
Volume exchanged in normal breathing
What is Inspiratory reserve volume (IRV)?
Volume maximally inspired above TV
What is Expiratory reserve volume (ERV)?
Volume maximally inspired below TV
What is Residual volume (RV)?
Volume remaining in lungs that cannot be exhaled
What is Total lung capacity (TLC)?
Sum of all of the volumes
What is Functional reserve capacity (FRC)?
Volume remaining in lungs after tidal exhalation
What is Vital capacity (VC)?
Sum of TV, IRV and ERV
What is Forced vital capacity (FVC)?
Volume of air forcibly expelled
How can you remember the Lung Volumes?
LITER
Also notice that a capacity is a sum of at least 2 volumes
What is the difference in obstructive vs restrictive lung disease in terms of FEV1/FVC?
What do we see with Emphysema in terms of damage to the lungs? Is this an obstructive or restrictive lung disease?
- degradation of the elastic matrix
- enlarged alveoli
- loss of recoil; can’t generate pressure to expel air
Obstructive!
1. results in a degraded lung that cannot resist the pull of the chest [lung volume \> normal level]
What do we see with Pulmonary fibrosis in terms of tissue damage? Is it obstructive or restrictive?
increased fibrotic material
increased compliance - can’t inflate lungs due to chest wall restriction
chest wall has degraded “spring” [lung volume < normal level]
RESTRICTIVE!
How does the lung behave with regards to compliance with volume vs. pressure?
Compliance is defined as the _____ of the volume/pressure curve
Compliance is defined as the slope of the volume/pressure curve
How does the total lung capacity (TLC) and Vital Capacity (VC) change with emphysema and fibrosis (2 answers)
________ helps to reduce surface tension and prevent alveoli from collapsing on themselves (atelectasis)
Surfactant helps to reduce surface tension and prevent alveoli from collapsing on themselves (atelectasis)
The law of LaPlace states that (what is the equation)?
The law of LaPlace states that P=2T/r
The law of LaPlace states that … (word definition)
increased surface tension increases the pressure required to expand the lungs
Why do we need to maintain a FRC (Functional Residual Capacity)?
Pressure required to expand smaller alveoli is higher than the pressure required to expand large ones
The lung is inflated by changes in pressure in the alveolar and pleural spaces relative to the ________ pressure
The lung is inflated by changes in pressure in the alveolar and pleural spaces relative to the atmospheric pressure
pleural pressure should be less than the ________ pressure to introduce air into the lungs
pleural pressure should be less than the alveolar pressure to introduce air into the lungs
a pneumothorax causes an ________ in pleural pressure, [resulting in decreased transmural pressure (internal surface pressure - external surface pressure) which will cause a collapsed lung and decrease the elastic properties and decrease the FRC
a pneumothorax causes an increase in pleural pressure, [resulting in decreased transmural pressure (internal surface pressure - external surface pressure) which will cause a collapsed lung and decrease the elastic properties and decrease the FRC
Dynamic lung mechanics - relationships between pressure and ________ in the lung
Dynamic lung mechanics - relationships between pressure and flow in the lung
Describe how airway resistance alters dynamic lung compliance.
(4 points to discuss)
- Resistance drops as area increases
- Airway resistance is greatest in mid-sized airways
- In small airways, the Cumulative Total cross-sectional area is very large due to their parallel arrangement, which lowers the resistance
- Pressure drives flow; P1V1=P2V2
What are the various pressures in the thoracic cavity when there is no inspiration/expiration? (no air moving)
transmural pressure =?
transpulmonary pressure = ?
Palveolar = ?
etc.
When the airway is closed, there is a positive transmural pressure which (opposes/enables) the expansion of the lungs and prevents inspiration
When the airway is closed, there is a positive transmural pressure which opposes the expansion of the lungs and prevents inspiration
What do the pressures in the thoracic cavity look like during inspiration?
Draw the flow vs. volume curve for inspiration. How does the flow change throughout inspiration?
Draw the flow vs. volume curve for expiration. When does airflow reach its peak? Are the intrathoracic airways narrowing or widening?
resistance in the airways is inversely proportional to airway ______ to the fourth power (just as with blood flow)
resistance in the airways is inversely proportional to airway radius to the fourth power (just as with blood flow)
_______ flow also increases airway resistance
turbulent flow also increases airway resistance
______ is an obstructive disease in which inspiration is impaired
Asthma is an obstructive disease in which inspiration is impaired
_______ is an obstructive disease with increased lung compliance; expiration is impaired
COPD is an obstructive disease with increased lung compliance; expiration is impaired
A _______ is a restrictive disease with decreased lung compliance and impaired inspiration
A fibrosis is a restrictive disease with decreased lung compliance and impaired inspiration
How do FEV1, FVC, FEV1/FVC, and FRC change between normal lung, asthma, COPd, and fibrosis?
During forced expiration, the reversal of the pressure gradient may result in a drop of airway pressure to where it is equal to the _______ pressure (equal pressure point)
During forced expiration, the reversal of the pressure gradient may result in a drop of airway pressure to where it is equal to the pleural pressure (equal pressure point)
How can people make their airway restrictive during forced exhalation in COPD?
a - end inspiration; b - quiet expiration; c - forced expiration
How does the flow vs. volume chart change for COPD?
How does the flow vs. volume chart change for people with fibrotic disease?
