Respiration

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Respiration Vocal Communication
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Avian Lungs

• Respiratory System
• Delivers O2 and rids CO2
• Thermoregulation
• Evaporative Heat Loss
• Vocal sound production

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Avian lungs with uni-directional flow or
flow-through ventilation

• (A). Dorsal view of the trachea (circled) and the
  lung of the Ostrich (Struthio camelus). The lungs
  are deeply entrenched into the ribs on the
  dorsolateral aspects (arrowhead). Filled circle,
  right extrapulmonary primary bronchus (EPPB).
  Note that the right EPPB is relatively longer,
  rather horizontal and relatively narrower
  compared with the left EPPB. Scale bar, 1 cm. (B)
  Close up of the dorsal aspect of the lung showing
  the deep costal sulci (s). Trachea, circled
  filled circle, right extrapulmonary primary
  bronchus. Scale bar, 2 cm (Maina and Nathaniel
  2001).

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cf. Mammalian Lung
Bi-directional flow
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Cervical
Interclavicular
Anterior
Posterior
Abdominal
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• 9 Airsacs
• Cranial
• 1 interclavicular sac
• 2 cervical sacs
• 2 anterior thoracic sacs
• Caudal
• 2 posterior thoracic sacs
• 2 abdominal sacs
• Form and Function
• Thin walled
• Little vasculature
• No gas exchange
• Bellows

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Respiratory Pathway

• Uni-directional, double cycle
• 1 - On first inhalation, air flows through the
  trachea bronchi primarily into the posterior
  (rear) air sacs
• 2 - On first exhalation, air moves from the
  posterior air sacs into the lungs
• 3 - With the second inhalation, air moves from
  the lungs into the anterior (front) air sacs
• 4 - With the second exhalation, air moves from
  the anterior air sacs back into the trachea out

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Inspiration

• the sternum moves forward downward while the
  vertebral ribs move cranially to expand the
  sternal ribs the thoracoabdominal cavity (see
  diagram below). This expands the posterior
  anterior air sacs (see 1 above) lowers the
  pressure, causing air to move into those air
  sacs.
• Air from the trachea bronchi moves into the
  posterior air sacs , simultaneously,
• air from the lungs moves into the anterior air
  sacs.

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(No Transcript)
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Expiration

• the sternum moves backward upward the
  vertebral ribs move caudally to retract the
  sternal ribs reduce the volume of the
  thoracoabdominal cavity. The reduces the volume
  of the anterior posterior air sacs (see 2 4
  above), causing air to move out of those sacs.
• Air from the posterior sacs moves into the lungs
  , simultaneously,
• air from the anterior sacs moves into the trachea
  out of the body.

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Parabronchus
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• arrows d. of airflow
• a arterial blood
• v venous blood
• - atria
• arrowhead infundibulum
• m mantle of gas exchange tissue
• air capillaries
• blood capilaries

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• Top Schematic of air flow (large arrows) and
  blood flow (small arrows) patterns constituting
  the cross-current gas-exchange mechanism
  operating in the avian lung. Note the serial
  arrangement of blood capillaries running from the
  periphery to the lumen of the parabronchus and
  the air capillaries radially departing from the
  parabronchial lumen. Bottom Pressure profiles of
  O2 and CO2 from initial-parabronchial (PI) to
  end-parabronchial values (PE) and in blood
  capillaries from mixed venous (Pv) to arterial
  blood (Pa). The PO2of arterial blood is derived
  from a mixture of all serial air-blood capillary
  units and exceeds that of PE. In mammals, the
  PaO2 cannot exceed that of end-expiratory gas
  (i.e., PE) (Brown et al. 1997).

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light
air capillary
TEM
rbc
lt0.2µm
surfactant layer
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Trachea
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The Syrinx