Topics:
Animal Physiology, Animal Refresher
Unpaired Air Sac in Birds
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Question (English)
Unpaired air sac in birds is the:
- Anterior thoracic air sac
- Cervical air sac
- Clavicular air sac ✓ Correct
- Abdominal air sac
Explanation:
Correct Answer: Clavicular air sac
The Clavicular (interclavicular) air sac is the only unpaired air sac in birds. All other 8 air sacs come in pairs.
Complete List of Avian Air Sacs
| Air Sac | Number |
|---|---|
| Cervical | 2 (paired) |
| Anterior (cranial) thoracic | 2 (paired) |
| Posterior (caudal) thoracic | 2 (paired) |
| Abdominal | 2 (paired) |
| Clavicular (interclavicular) | 1 (unpaired) ✔ |
| Total | 9 air sacs |
Function of Air Sacs
- Air sacs are avascular → no direct gas exchange occurs in them.
- They act as bellows — provide one-way (unidirectional) airflow through the parabronchi where actual gas exchange occurs.
- This unidirectional flow makes avian respiration more efficient than mammalian bidirectional flow.
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
