Part I Flashcards
Describe the pathway of ventilation.
Cerebral cortex and other higher brain centers –> respiratory center (medulla) –> spinal cord –> respiratory muscles –> lung and chest wall–> respiratory membrane –> blood
What is the point of the respiratory center?
Sets the basic drive of ventilation
Where does ventilation actually occur?
At the lung and chest wall
How many layers are there for the respiratory membrane? What are the room layers?
2, respiratory membrane and capillary wall
What do mechanoreceptors control?
Coughing, airway constriction, hyperventilation
What do chemoreceptors monitor?
CO2, O2, pH in the blood
What is the coupled reaction in the ventilation cycle?
Ventilation of alveoli coupled with perfusion of pulmonary capillaries
Alveolar pressure oscillates around what?
Atmospheric pressure
Where does alveolar pressure sit during Inspiration?
Below atmospheric pressure
Where does alveolar pressure sit during expiration?
Above atmospheric pressure
Where does alveolar pressure sit at the end of either expiration or inspiration?
Alveolar = atmospheric
Define Transpulmonary pressure.
Measures the recoil tendency of the lung, which peaks at the end of inspiration
TLC Definition
Total lung capacity, lungs at full inflation
TLC
IRV TV ERV RV
IC definition
Inspiration capacity, max volume one can inspire
IC
TV IRV
FRC definition
Functional residual capacity, air left in lungs after normal expiration
FRC
RV ERV
IRV definition
Inspiratory reserve volume, max volume after normal inspiration
TV definition
Tidal volume, air moved in or out at each breath
ERV definition
Expiration reserve volume, max volume you can expire after after normal expiration
RV definition
Residual volume, air left in lungs after max expiration effort
VC definition
Vital capacity, max air one exchanges in a respiratory exchange
VC
IRV TV ERV
Inspiratory muscles
Diaphragm, external intercostals, anterior serratus, posterior serratus, superior serratus, Levator costarum, scalenes
Expiration muscles
Abdominals, internal intercostals, posterior serratus, inferior serratus, transverse thoracis, pyramidals
What to inspiratory muscles do?
Lift rib cage, EXCEPT diaphragm
What does the diaphragm do?
Drops floor of the thoracic cage
What do expiration muscles do?
Pull riback cage down during forced expiration, otherwise expiration is passive
Define pleural pressure.
Negative pressure between the parietal and visceral pleura
What does pleural pressure do?
Keeps lung inflated against chest wall
What is alveolar pressure?
Subatmospheric during Inspiration, supratmospheric pressure during expiration
Describe parietal pleura.
Firmly attached to the thoracic cage and reflects back at the hillman to form the visceral pleura
Describe visceral pleura.
Firmly attached to lungs
Describe the recoil relationship at the end of expiration.
Chest wall forces are opposite, but equal to lungs recoil forces
What is the equation for compliance?
Change in pressure divided by the change in time
Define hysteresis
When the plegal pressure changes at a faster rate than the lung expands during Inspiration
Why is it easier to fill a saline lung compared to an air filled lung?
Because the surface tension forces have been eliminated in the saline filied lung
What does the thoracic cage do to the compliance of the lung?
The thoracic cage reduces the compliance of the lung by 1/2 at the end of a normal expiration (functional residual capacity)
When is compliance greatly reduced?
At high or low lung volumes
What is the primary factor in the work of breathing?
Elastic work/compliance work
What are other ways of work for breathing?
Tissue resistance work, airway resistance work, energy required for ventilation
Ventilation takes up how much of the body’s total energy?
3-5%
What is tissue resistance work?
Viscosity of chest and lung wall
