Pulmonary 2 Flashcards
What is the alveolar pressure during:
- Inspiration
- Expiration
- how does air flow?
- Alveolar Pressure is BELOW atmospheric (so negative pressure pulls air in)
- Alveolar Pressure is ABOVE atmospheric
Air flows down a pressure gradient
- so during inspiration it is pulled in, expiration it flows out
What is the relationship of Pressure and Volume?
Pressure is INVERSELY proportional to volume
Ex: as the volume of a container decreases, the pressure rises
What are the 2 major muscles of INSPIRATION?
- Diaphragm
- External Intercostals
Diaphragm flattens & moves DOWN: enlarge cavity VERTICALLY
External Intercostals: move UP and OUTWARD –> enlarge cavity in lateral & anterior-posterior direction
(they relax after inspiration is complete & rib cage falls)
What muscles are used for FORCED inspiration?
Accessory Muscles of Inspiration:
- Scaleneus
- SCM
By what mechanism do we EXPIRE? (passive or active)
What muscles are used for FORCED ACTIVE Expiration?
PASSIVE!
Abdominal muscles contract –> increase abdominal pressure and pushes diaphragm UP
Internal Intercostal Muscles flatten rib cage & pull ribs DOWN & INWARD
What are the only lung volumes that a spirometer cannot measure? What is another technique to measure this?
- RV, FRC, TLC
- Helium Dilution
- more dilution = larger capacity
What are the volumes of the following:
- Tidal Volume (Vt)
- Inspiratory Reserve Volume (IRV)
- Expiratory Reserve Volume (ERV)
- Residual Volume (RV)
- 500 mL
- 3000 mL
- 1200 mL
- 1200 mL
What is the following defined as:
- Change in volume that occurs with cycle breathing
- Volumes that can be in/exhaled in addition to the TIDAL VOLUME
- Volume that remains in the lung even after forced expiration
- Tidal Volume
- Inspratory/Expiratory Reserve
- Residual Volume (cannot be measured with spirometry)
What are the equations for the following:
- Inspiratory Capacity
- Functional Residual Capacity
- Vital Capacity
- Total Lung Capacity
- IC = IRV + Vt –> 3500 mL
- FRC = ERV + RV –> 2400 mL
- VC = IRV + Vt + ERV –> 4600mL
- TLC = IRV + Vt+ ERV + RV
- -> 5800 mL
What is the term for the maximum amount of air that can be moved from deep expiration to deep inspiration?
Vital Capacity
Define:
FRC
TLC
What is unique about these in terms of the spirometer?
FRC = Volume of air in the lungs when all respiratory muscles are relaxed
(lung pulls in, chest wall springs out)
TLC:
total volume of air held by the lung
- includes Alveolar Volume & Dead space volume
- scaled to the size of a person
-**cannot be measured with spirometer! **
What does Helium Dilution measure?
Measures the FRC ( the volume of air in lungs when all muscles are relaxed)
-patient relaxes to FRC volume and a valve is opened allowing helium during inhalation/exhalation
FRC = V1 * (C1-C2) / C2
What does a larger FRC signify?
Larger FRC = the more the initial helium concentration gets diluted
(dilution principle)
What are 2 ways to measure FRC?
- Helium Dilution
2. Body Plethysmography
What is compliance of the lung defined as? What does it measure?
Ability of any structure to comply with deforming forces
- measures the elastic properties of the lung
change in lung volume/ per 1 cm of H2o in distending pressure
What does lung compliance depend on? When is compliance maximized?
VOLUME of air within the lung
- volumes near FRC = compliance is maximized!
(compliance decreases at higher volumes)
What is hysteresis? What causes hysteresis?
Hysteresis: inflation of the lung has a different curve than deflation of the lung (inspiration/expiration)
- Surfactant causes Hysteresis
When are external intercostals & Accessory Muscles used?
DURING EXERCISE ( for inspiration)
- Internal intercostals = used for forced EXPIRATION
When is compliance maximal? What is the equation for compliance?
Max at MIDDLE RANGE of pressures
- compliance is the change in pressure in going from FRC to FRC +1
What is Specific Lung Compliance?
Absolute compliance depends on the volume of the structure
ex: child lung vs. adult lung
Compliance is tissue specific based on the VOLUME being evaluated
SC = Lung compliance/ lung volume
(compliance = volume/pressure)
How does the specific compliance change if half of a lung is removed (for example)?
The total complaince of the lung is less, BUT the specific compliance does NOT change!
- since it is a measure of compliance/volume
What 2 properties does inflation of the lung overcome?
- Viscoelastic properties of lung parenchyma by stretching elastic & collagen fibers
- Surface tension of alveolar epithelium set up between air/water interface (surfactant reduces tension, but not to zero)
What are the affects of Fibrosis & Emphysema on Compliance?
Fibrosis - Compliance Decreases
Emphysema - Compliance Increases(greater slope)
- alveoli expand in diamter, but decrease in SA
What are the affects of Fibrosis & Emphysema on FRC?
Fibrosis - FRC DECREASES
- more lung recoil
- intrapleural pressure becomes more negative (more pull of the lung = increase volume)
Emphysema - FRC INCREASES
- less lung recoil
- intrapleural space less negative (less pull of the lung on the chest wall)
What determines the volumes of the air in the lungs?
Lung - Chest wall interactions
- move together as a unit = same volume changes
What determines the volume of air in the lungs (2)
- Balance between elastic properties of the lung & elastic properties of the muscles of the chest wall
- Elastic Recoil of the lung is high
- w/o external forces the lung volume would be airless & chest would expand
What are the equations for the following:
- Transpulmonary (Translung) Pressur
- Transmural Pressure across chest wall
- Pressure Across Respiratory System
- PL = PA - Ppl
(760-756) - Pw = Ppl - Pb
- Prs = PL + Pw
= (PA- Ppl) + (Ppl + Pb)
= PA - Pb
Pb = (barometric pressure = atmospheric)
Where is the equilibrium position for: (in regards to FRC)
- Chest wall alone
- Lung alone
- above FRC
2. below FRC
How is FRC achieved?
Balance between the outward pulling of chest wall & the inward pulling of the lung
What is alveolar pressure the sum of? What is transpulmonary pressure?
Sum of pleural pressure & elastic recoil pressure
transpulmonar = difference between pleural pressure and alveolar pressure
What is a pneumothorax? What is the TX?
Air/ gas in the pleural space leading to a separation of lung & chest wall
- TX with 1. Chest tube 2. Under water seal drain
What are the 3 phases of dynamic breathing?
- Dynamic Inspiration
- Dynamic Expiration
- Static Pause
What is intrapleural pressure always?
NEGATIVE!
- always below atmospheric pressure
What is the pressure across the respiratory system when there is NO AIR FLOW?
ZERO
During quiet breathing, pressure changes are large & intrapleural pressure is always above atmospheric.
True or False?
FALSE
Pressure changes are SMALL & intracellular pressure is always BELOW atmospheric pressure
How are lung volumes determined?
By the balance between elastic recoil of the lung & properties of chest/wall muscles
At FRC, how is inward recoil of the lung & outward recoil of the lung in relation to one another?
EQUAL! = balances
The recoil pressure of the lung is attributable to what? (2)
- Elastic properties
2. Surfactant
What occurs to the following during INSPIRATION:
- Volume
- Pleaural Pressure
- Flow
- Alveolar Pressure
- Volume INCREASES in chest cavity
- Pleural Pressure - Intrapleural pressure becomes more negative –> stops at -8 cm H20
- Flow - air flows INTO the lung due to the pressure gradient (via negative suction)
- Alveolar Pressure - space is expanded so the pressure falls BELOW atmospheric pressure (-1 cmH20)
What occurs to the following at the end of INSPIRATION:
- Volume
- Pleaural Pressure
- Flow
- Alveolar Pressure
- Volume - Lung volume PEAKS above FRC
- . Intra pleural pressure is static at -8cm H20
- Flow - STOPS
- Alveolar pressure re-equilibriates with atmospheric at 0 cm H20
What occurs to the following at the end of EXPIRATION:
- Volume
- Pleaural Pressure
- Flow
- Alveolar Pressure
- recoil forces pull the chest wall inward & diaphragm up using the elastic forces in the lung
1. Volume Decreases
2. Intrapleural Pressure becomes LESS NEGATIVE
3. Flow OUT OF THE LUNG
4. Alveolar are compressed so pressure EXCEEDS atmospheric
AIR IS PUSHED OUT OF THE LUNG and lung volume falls back to FRC
