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

Breathing cycle

  • Continous gas exchange
  • “Flow through” system
    • Constant breathing (ø in and out breathing)
      • Flying (reason)
  • “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
    • Expiration (cycle 1)
      • Caudal sacs → lungs
    • Inspiration (cycle 2)
      • Lungs → cranial sacs
    • Expiration (cycle 2)
      • Cranial sacs → ventrobronchus → trachea → out

Countercurrent flow and the lungs

  • Compression of air sacs (not lungs)
  • Lungs
    • Noncompliant
    • Stiff
  • Continous gas exchange
    • High O2 need during flying
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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: used air
  • Caudal group: fresh air
  • Trachea
  • Mesobronchus
  • Dorsobronchi
  • Parabronchi
  • Ventrobronchi
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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
  • Inspiration (cycle 2)
    • Air from lungs → cranial sacs
  • Expiration (cycle 2)
    • Air from cranial sacs → ventrobronchus → trachea → out
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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
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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
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