Topic 39 - The respiration of birds Flashcards
1
Q
Words to include
A
- Air sacs
- Cranial group
- Cervical sac
- Clavicular sac
- Cranial thoracic sac
- Used air
- Caudal group
- Abdominal sac
- Thoracic caudal sac
- Fresh air
- Cranial group
Breathing cycle
- Continous gas exchange
- “Flow through” system
- Constant breathing (ø in and out breathing)
- Flying (reason)
- Constant breathing (ø in and out breathing)
- “Bellows” action of air sacs
- Countercurrent flow mechanism
- Cycle
- Inspiration (cycle 1)
- Caudal sacs + parabronchi
- Air from outside
- Cranial sacs expand (not from inhaled air)
- Air from lung
- Caudal sacs + parabronchi
- Expiration (cycle 1)
- Caudal sacs → lungs
- Inspiration (cycle 2)
- Lungs → cranial sacs
- Expiration (cycle 2)
- Cranial sacs → ventrobronchus → trachea → out
- Inspiration (cycle 1)
Countercurrent flow and the lungs
- Compression of air sacs (not lungs)
- Lungs
- Noncompliant
- Stiff
- Continous gas exchange
- High O2 need during flying
2
Q
Explain the anatomical composition of the breathing system in birds
A
- Birds ventilate their lungs not by expanding the lungs themselves, but by expanding the air sacs
- The air sacs er balloon-like structures at the “ends” of the airway system
- Each airsacs contains wall of squamous epithelium
- Two large groups of air sacs (total 8 sacs):
-
Cranial group:
- Cervical sac
- Clavicular sac
- Cranial thoracic sac
-
Caudal group
- Abdominal sac
- Thoracal caudal sac
-
Cranial group:
- Cranial group: used air
- Caudal group: fresh air
- Trachea
- Mesobronchus
- Dorsobronchi
- Parabronchi
- Ventrobronchi
3
Q
Breathing cycle
A
- Gas exchange in the lungs is continous
- “Flow through” system, not in and out breathing cycle like mammals
-
Inspiration (cycle 1)
- Air flows directly to the caudal sacs + parabronchi
- The cranial sacs also expand on inhalation, but they do not receive inhaled air from the outside, but from the lungs
-
Expiration (cycle 1)
- Air from caudal sacs → lungs
- Not throught the mesobronchus
- Air from caudal sacs → lungs
-
Inspiration (cycle 2)
- Air from lungs → cranial sacs
-
Expiration (cycle 2)
- Air from cranial sacs → ventrobronchus → trachea → out
4
Q
Physological characterisitcs of avian breathing
A
- Countercurrent flow mechanism for gas exchange in the lung
- The air sacs are compressed, not the lungs
-
“Flow-through” system
- Great importance because flight demands an enormous amount of oxygen exchange
- Continous gas exchange, supporting high
- Constant breathing
5
Q
Avian lungs
A
- The lungs are stiff and noncompliant
- The air sacs act as bellows to suck air in and blow it out, and also to hold part of the total volume