Page 276 - Industrial Ventilation Design Guidebook

GLOSSARY 237

Functional residual capacity (FRC): Gas volume remaining in the airway at
end-tidal exhalation.
Gingival crevicular fluid: Liquid found in gingival crevices located around
the base of teeth.
Hemoglobin saturation level: The extent to which the oxygen-bearing ca-
pacity of hemoglobin in red blood cells is utilized.
Homeostasis: Tendency for an organism to maintain internal physiological
stability.
Hydrostatic pressure: Force generated by a fluid at rest, directed perpendic-
ular to a surface.
Hygroscopic: Material that readily adsorbs or absorbs moisture from the
atmosphere.
Hyperbaria: Pressures greater than standard atmospheric pressure (760 mm
Hg).
Inspiratory reserve volume (IRV): Maximum additional volume one can in-
spire from end-tidal inspiration.
Intercostal muscles: Muscles connecting the ribs that aid the diaphragm in
propelling air through the respiratory tract.
Interstitial: Space found between cells.
Jet: Rapidly expanding flow exiting from a very small orifice.
Lower airways: The portion of the human conducting airways distal to the
larynx.
Macrophage: A large ameboid phagocytic cell.
Mean mass aerodynamic diameter (MMAD): Mean diameter of theoretical
particles with a 1 g/cm density having the same settling velocity as an ac-
tual group of measured particles calculated on the basis of particle mass.
Meatus: An opening or passage;. . . of the nasal cavity: air passages between
the nasal conchae and the later wall of the nasal septum.
Metachronal wave: Synchronized ciliary movement over a relatively large
airway region that is responsible for the transport of objects and materials
along the mucociliary escalator.
Microvilli: Minute projections of cell membrane that greatly increase apical
surface area.
Minute ventilation: Volume of air expired or inspired during one minute of
breathing.
Mucociliary escalator: Mechanism that removes extracellularly-derived ma-
terials from the conducting airways by entrapping these materials in mu-
cus that is continuously moved toward the epiglottis by synchronized
ciliary movement.
Mucus: Viscous glycoprotein, proteoglycan secretion of goblet cells and
mucus glands.
Nares: Orifices leading into the nasal cavity; nostrils.
Nasal cavity: Airway passages between the nares and posterior termination
of the nasal septum.
Nasal turbinates: Region within the nasal cavity denoted by convoluted
bony projections (conchae).
Nasopharynx: Airway passage between the posterior termination of the na-
sal septum and lower border of the soft palate.