Page 277 - Industrial Ventilation Design Guidebook

238 CHAPTER 5 PHYSIOLOGICAL AND TOXICOLOGiCAL CONSIDERATIONS

Norihygroscopic: Material that resists adsorbing or absorbing atmospheric
water vapor.
Noxious: Injurious.
Olfaction: The physiological function of sensing odors.
Oral cavity: Airway passage between the lips and lower border of the soft
palate.
Oronasal breathing: Breathing simultaneously through both the nasal and
oral cavities.
Qropharynx: Airway passage between the lower border of the soft palate
and epiglottis.
Oxygen uptake: Rate of oxygen transfer from air resident in the pulmonary
airways to the pulmonary bloodstream. This is driven by the oxygen con-
centration gradient and depends on metabolic demand.
Parenchyma: The essential or specialized part of an organ; gas exchange
portions of the respiratory tract (alveoli, respiratory bronchioles).
Particle growth: Increase in particle size due to hydration.
Partition coefficient: Quantitative expression of the partition equilibrium of
a material between two immiscible liquid phases; usually expressed as the
ratio of concentrations between the two phases.
Patency: Extent of a conduit (airway, blood vessel) being open or not obstructed.
Pathogen: Disease-producing organism or substance.
Peak expired flow (PEP): Gas volume forcibly expired within the time inter-
val t (typically t = 1.0 seconds).
Perfusion: Passage of blood through a blood vessel.
Peribronchial surface: Surface surrounding a bronchus.
Periciliary fluid: Transepithelial secretion along the conducting airways con-
sisting primarily of water.
Phagocytosis: Process describing the engulfment and destruction of extra-
cellularly-derived materials by phagocytic cells, such as macrophages and
neutrophils.
Pleura: Folded membrane surrounding the lungs. Space between the visceral
and parietal layers (pleural space) is fluid-filled and determines transpul-
monary pressure.
Poiseuille flow: Parabolic laminar flow in a straight tube.
Portal: The point at which something enters the body; in the airway, the
nares or lips.
Proximal: In the airways, positioned relatively closer to the nares.
Pulmonary: Pertaining to or affecting the lungs.
Pulmonary airways: Portion of respiratory tract (alveoli, respiratory bron-
chioles) where gas exchange occurs.
Pulmonary perfusion rate: Volumetric flow rate within the pulmonary veins.
Reentrainment: Return of material to an airstream after deposition onto a
surface.
Residence time: Time interval during which an identifiable portion of a
fluid flow remains within a given volume.
Residual volume (RV): Minimum non-collapsible volume within the airway.
Resistance vessels: Microcirculatory blood vessels (arterioles, pre-capillary
sphincters) used to regulate blood flow in a specific tissue.