2. How we breathe Flashcards
2 zones of lung
1) Conducting zone
2) Respiratory zone (blood-gas interface)
Conducting zone
no gas exchange
trachea to terminal bronchioles
generations 0-16
BULK FLOW
Respiratory zone
Volume 2.5-3 L
respiratory bronchioles, alveolar ducts and alveolar air sacs
generations 17-23
DIFFUSION
Boyle’s Law
P1V1 = P2V2
Intrapleural pressure
between pleural membranes
Intrapulmonary pressure
in the alveoli
Transpulmonary pressure
Intrapulmonary minus Intrapleural
Flow
Pressure x resistance
Asthma
Reduced airway radius
Increased resistance
Intermittent smooth muscle contraction
Vital capacity (VC)
Maximum volume breathed out SLOWLY after maximum inspiration
Forced vital capacity (FVC)
Maximum volume breathed out as QUICKLY as possible after maximum inspiration
Forced expiratory volume in 1 second (FEV1)
Volume expired in 1s during FVC
Values for Normal/Obstructive/Restrictive FEV1/FVC
Main site of airway resistance
Intermediate bronchi
How are CRV, TLC, FRC measured?
Plethysmography
sealed chamber
Tidal volume
The amount of air which enters the lungs during normal inhalation at rest
The average tidal volume is 500ml
Residual Volume
volume of air still remaining in the lungs after the most forcible expiration possible
IRV
the maximal amount of additional air that can be drawn into the lungs by determined effort after normal inspiration
ERV
the additional amount of air that can be expired from the lungs after normal expiration
Resistance changes with lung volume
At larger lung volumes, resistance is lower
because airways are dilated due to radial traction
