Respiratory volumes, capacities, and pressures

Intrapulmonary pressure

pressure in the alveoli

Intrapleural pressure

pressure in the pleural cavity

Transpulmonary pressure

difference between intrapulmonary and intrapleural pressure

Tidal volume (TV)

amount of air inhaled / exhaled throughout rest

Inspiratory reserve volume (IRV)

amount of air forcefully inhaled after normal inspiration

Expiratory reserve volume (ERV)

amount of air forefully exhaled after normal exhalation

Residual volume (RV)

amount of air remaining in lungs after forced expiration

Total lung capacity (TLC)

maximum amount of air in lungs after maximum inspiration

TLC = TV + IRV + ERV + RV

Vital capacity (VC)

maximum amount of air that can be exhaled after maximum inhalation

VC = TV + IRV + ERV

Inspiratory capacity (IC)

maximum amount of air that can be inhaled after normal expiration

IC = TV + IRV

Funcitonal residual capacity (FRC)

volume of air remaining in the lunfs after a normal expiration

FRC = ERV + RV

External respiration

O2 diffuses from lungs to blood; CO2 diffuses from blood to lungs

Internal respiration

O2 diffuses from blood to tissues; CO2 diffuses from tissues to the blood

Type 1 alveolar cells

squamous epithelium; form alveolar walls

Type 2 alveolar cells

cuboidal epithelium (secrete); secrete surfactant (prevents alveolous from collapsing); secrete antimicrobial proteins