Related Experiment Videos
Pulmonary blood flow distribution in panting ostriches
Summary
Ostriches increase ventilation during heat stress by shunting air around gas exchange areas, not by altering lung blood flow distribution. This unique respiratory adaptation prevents hypocapnia and alkalosis in extreme heat.
Area of Science:
- Physiology
- Avian Biology
- Respiratory Physiology
Background:
- Ostriches (Struthio camelus) uniquely increase ventilation during heat stress without hypocapnia or respiratory alkalosis.
- This suggests a novel mechanism for thermoregulation in birds.
Purpose of the Study:
- To investigate if ostriches redistribute pulmonary blood flow during panting.
- To determine if this redistribution creates a ventilation-perfusion (V/Q) imbalance.
Main Methods:
- Radioactively labeled microspheres were used to measure pulmonary blood flow distribution.
- Measurements were taken in ostriches at rest (15°C) and during severe panting (45°C).
Main Results:
- At rest, blood flow was highest in the neopulmo and specific paleopulmo regions.
- During panting, blood flow was not shunted around the lung; flow to the neopulmo decreased.
- Pulmonary blood flow distribution became more homogeneous craniocaudally but remained nonhomogeneous mediolaterally.
Conclusions:
- The decrease in gas exchange during ostrich panting is likely due to ventilation shunting around the parabronchial region.
- Alterations in V/Q patterns within the lung are less probable causes.
- This highlights a unique avian respiratory adaptation to heat stress.