Question

The respiratory flow of air in the lungs is affected due to air pollution. If you have to model

respiratory flow write four essentials for the model.

Answer 1

Four Factors Affecting Air Flow

Airway Caliber

• laminar flow () =  pressure (P) / resistance (R)
• slope of line = 1/R = conductance
• resistance (R) to laminar flow  1/radius⁴
•  airway caliber (secretions, bronchoconstriction): < R and <  P

Air-Flow Profile

• laminar flow (<) increases linearly with < driving pressure
• non-laminar flow (<) increases curvilinearly with < driving pressure
• R_{non-laminar flow} is effectively greater than R_{laminar flow} due to turbulence
• for any given < P, <_non-laminar < <_laminar
• or any given <, <P_non-laminar > < P_laminar

Airway Generation

• Airway Generationin general, regional airway resistance decreases as a function of airway generation
• in specific, the highest regional resistance is at generation 4
• medium sized bronchi of short length and frequent branchings highly non-laminar air flow with extreme turbulence

Lung Volume 

• Lung Volumetotal airway resistance = summation of serial regional resistances
• R_total decreases hyperbolically with increases in lung volume
• conductance_total increases linearly with increases in lung volume (dashed line)
• increases in lung volume cause increases in radius due to tethering of the airways
• R_total can be partitioned into two components
• R_peripheral : low resistance (laminar & diffusive zones)
• R_central : high resistance (turbulent flow zone)
• R_central >>> R_peripheral (50% of resistance in nasal passages alone)

More information:

https://www.meddean.luc.edu/lumen/MedEd/medicine/pulmonar/physio/pf2.htm