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Journal of Experimental Biology 142,373-385 (1989)
Published by Company of Biologists 1989

Gas Exchange and Air-Sac Composition in the Unanaesthetized, Spontaneously Breathing Goose

PETER SCHEID 1, M. ROGER FEDDE 1, and JOHANNES PIIPER 1

1 Institut für Physiologie, Ruhr-Universität Bochum, FRG and Abteilung Physiologie, Max-Planck-Institut für experimentelle Medizin, Göttingen, FRG

Gas exchange variables were measured in unanaesthetized domestic geese fitted with rubber facemasks and indwelling air-sac and arterial catheters. The results were analysed on the basis of functional models.

1. Ventilation was characterized by low frequency (8.4 min-1) and high tidal volume (29-3 ml kg-1).

2. Average values (± S.E.) of arterial blood variables were as follows: PO2 = 12.9 ± 0.2 kPa, PCO2 = 4.2±0.2kPa, pH = 7.52 ±0.01. Body temperature was 41.4 ±0.2°C.

3. The gas exchange ratio (calculated with reference to inspired gas) of caudal air sacs (average 1.09) was higher, and that of cranial air sacs (0.73) lower, than that of mixed-expired (0.82) or end-expired gas (0.78). This pattern can be explained by a higher effective ventilation/perfusion ratio in the neopulmo than in the paleopulmo.

4. During inspiration, the neopulmo was estimated to contribute about 7% to the overall inspiratory O2 uptake, and about 18% to the CO2 output. Total inspiratory gas exchange was twice that during expiration.

5. Arterial PO2 was close to, but PCO2 lower than, the partial pressure in cranial air sacs and in end-expired gas. This can be explained on the basis of a crosscurrent gas exchange system with unequal distribution of ventilation to perfusion between functional compartments.

Key words: air sacs, birds, blood gases, diffusing capacity, parabronchial gas exchange, respiratory air flow

Accepted on August 15, 1988






© The Company of Biologists Ltd 1989