Avian Respiration

Question 1

Describe the flow through the upper respiratory system the lungs and the air sacs

Answer 1

Inhalation
Sternum forward and down, ribs cranially, Lower pressure, air sacs expand
Air moves through the nasal cavity past the larynx (passing through URS). The air flows into the caudal air sacs from the trachea.

Exhalation
Sternum back and up, ribs caudally, decrease volume, forces air out of air sacs
Air is forced into the lungs where has exchange takes place in tubular capillaries rather than alveoli

Inhalation
Air sacs expand drawing up the air from the lungs into the cranial air sacs

Exhalation
Air sacs contract expelling air through the trachea

Question 2

Describe the structure of the avian lung

Answer 2

Firmly attached to the thoracic wall and remains constant in volume during both phases of respiration.

The primary bronchus enters the lung, giving off at the branching into 4 sets of secondary bronchi before it enters the abdominal air sac

Parabronchi are primarily responsible for continuous gas exchange using a counter current system ato oxygenate and remove waste from the blood

Question 3

Describe the structure and function of the avian air sac system

Answer 3

Act like reservoirs

Poorly vascularized, no gas exchange

9 (or sometimes 8) air sacs

Connected with pneumatic bones

Evaporative heat loss

Sound production

Question 4

Describe the role of the skeletal system in avian respiration

Answer 4

Pneumatic bones: Reduce weight

- skull

- humerus

- clavicle

- keel (sternum)

- pelvic girdle

- vertebrae