Lung (3) Flashcards
O2 consumption
240 - 280 ml/min
Co2 Production
190 - 220 ml/min
Overall water loss per day from breathing
250 ml/day
Layers of Mucous
- Inner Sol layer (Cilia)
- Outer gel layer
Clearance of particles
- Impaction: Nasal cavity
- Sedimentation: lower airways
- Diffusion: alveoli (macrophage clearance)
Lung metabolic function
- Renin: Angiotensinogen to Ang1
- ACE: Ang1 to Ang 2
- ACE2: Ang2 to Ang 1-7
(viruses use ACE2 to enter)
Dichotomic divisions
- Conducting zone (1-16) : Dead space
- Respiratory zone (17-23) : alveolar space
Physiological Dead space
Sum of anatomical dead space (150ml) and Functional/Alveolar dead space (negligible)
Functional Dead space
Space of the ventilated alveoli that does not participate in gas exchange
Alveolar cells
- Type-1: Squamous for gas exchange
- Type-2: Smaller, produce surfactant
Alveolar Ventilation
4900 ml/min
Dynamic lung volumes
Related to rate at which air flows in/out of lungs
Static lung volumes
Not affected by the rate of air in/out of lungs
Tidal Volume (TV)
500 ml
Amount of air entering/leaving the lungs without extra effort
Inspiratory Reserve Volume (IRV)
3100 ml (1900 ml F)
Max inspiration above tidal volume
Expiratory Reserve Volume (ERV)
1200 ml (800 ml F)
Volume exhaled above tidal volume
Residual Volume (RV)
1200 ml (1000 ml F)
Air remaining in the lungs after complete exhalation
Inspiratory Capacity (IC)
3600ml (2400 ml F)
Largest amount that can be inhaled
(TV+IRV)
Functional Residual Capacity (FRC)
2400 ml (1800 ml F)
Volume after normal expiration
Vital Capacity (VC)
4800 ml (3200 ml F)
Entire volume that can be maximally inhaled and exhaled
Total Lung capacity (TLC)
6000 ml (4200 ml F)
All of the lung volume
(VC + RV)
How do we determine FRC
- Helium Dilution method
- Plethysmography
- Spiroscope
- Clinical spirogram
Helium Dilution method
Closed circuit with spirometer and patient asked to breathe until helium is equilibrated
c1 * v1 = c2 * (v1+v2)
v2 = FRC
Plethysmography
Air tight cabin with shutter, after expiration patient is asked to do a forceful inspiration while shutter is closed. Chest extends and pressure is measured.