Pulm 3 & 4 Flashcards
Air flow at a given pressure gradient is determined by
- pattern of gas flow
- resistance to air flow by airways
Patterns of Gas Flow
- Laminar
- Transition al
- Turbulent
Air way Resistance
- directly proportional to the airway length and gas viscosity
- inversely proportional to airway radius
Three types of inspiratory airflow profiles
1) Turbulent - generations (0-9)
2) Laminar - generations (10-16)
3) Diffusive - generations (17-23)
What is the most important Pulmonary Function Test (PFT)?
Forced Expiration Volume/Forced Vital Capacity
FEV/FVC
ratios greater than 75% are considered normal.
-less is considered obstructive
Whats happens during inspiration when lung volume increases?
- Force of inspiratory muscles decreases
- Lung recoil pressure increases
- Airway resistance decreases
- Max inspiratory flow occurs halfway between TLC & RV
What happens during expiration?
- PEFR occurs early (first 20% of cycle)
- Flow rate decreases towards RV = expiratory flow limitation
Henry’s Law
The concentration of dissolved ion is equal to its partial pressure
Describe how air composition changes in the airway
air is warmed to to body temperature (37 C) and completely humidified (100 %)
Respiratory Quotient
0.8
Partial pressure of O2 in trachea
150 mmHg
Partial pressure of O2 in alveoli
102 mmHg
Partial pressure of CO2 in alveoli
40-45 mmHg
The fraction of alveolar CO2 is determined by . . .
- metabolism = CO2 production
- rate of elimination = alveolar ventilation
What are the reasons for regional differences at the lung level?
- anatomically, the base of the lung has more alveoli to receive more air
- at FRC, the base of the lung is more compliant than the apex
