Avian lungs have a unique unidirectional flow pattern, airflow being directed by 'aerodynamic valves'. The functioning of these valves is heavily dependent upon inertial forces in the gas. Such forces are also important in mammalian lung under some circumstances (e.g., high frequency ventilation and panting). The avian respiratory system provides advantages for study because it has large gas reservoirs, separate from gas exchange regions. This enables measurement of pressures and gas concentrations at various sites in the system, and tracing of gas flow routes which would be difficult or impossible to do in mammalian lung. While the existence of aerodynamic valves in bird lung has been recognized for half a century and flow routes through the airways have been well described, there is little understanding of the actual fluid dynamic mechanisms by which the aerodynamic valves in avian lungs direct flow. We will (1) characterize the physical parameters (gas velocity, gas density and viscosity, steadiness of flow) which affect the valves by injecting and sampling tracer gas at various sample sites in the goose respiratory system to determine flow routes. (2) use anatomical and gas flow data to develop physical and computational models which describe essential features of the valves, and (3) investigate the effect of variation in physiological conditions on the performance of valves.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL035420-02
Application #
3349273
Study Section
Respiratory and Applied Physiology Study Section (RAP)
Project Start
1985-12-01
Project End
1988-11-30
Budget Start
1986-12-01
Budget End
1987-11-30
Support Year
2
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Harvard University
Department
Type
Schools of Public Health
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Wang, N; Banzett, R B; Nations, C S et al. (1992) An aerodynamic valve in the avian primary bronchus. J Exp Zool 262:441-5
Banzett, R B; Nations, C S; Wang, N et al. (1992) Mechanical independence of wingbeat and breathing in starlings. Respir Physiol 89:27-36
Banzett, R B; Nations, C S; Wang, N et al. (1991) Pressure profiles show features essential to aerodynamic valving in geese. Respir Physiol 84:295-309
Wang, N; Butler, J P; Banzett, R B (1990) Gas exchange across avian eggshells oscillates in phase with heartbeat. J Appl Physiol 69:1549-52
Fredberg, J J; Allen, J; Tsuda, A et al. (1989) Mechanics of the respiratory system during high frequency ventilation. Acta Anaesthesiol Scand Suppl 90:39-45
Butler, J P; Banzett, R B; Fredberg, J J (1988) Inspiratory valving in avian bronchi: aerodynamic considerations. Respir Physiol 72:241-55
Wang, N; Banzett, R B; Butler, J P et al. (1988) Bird lung models show that convective inertia effects inspiratory aerodynamic valving. Respir Physiol 73:111-24
Banzett, R B; Butler, J P; Nations, C S et al. (1987) Inspiratory aerodynamic valving in goose lungs depends on gas density and velocity. Respir Physiol 70:287-300