Avian Respiratory Anatomy/Physiology Flashcards
Unique aspects of avian respiratory system
- complete tracheal rings
- some birds have two trachea (penguins)
- trachea is longer and wider than trachea of a comparably-sized mammal
- anatomic dead space larger
- unidirectional gas exchange
Avian lungs are rigid or pliable?
Rigid
Do birds have a diaphragm?
No
Definition of syrinx
Voice box
7 airsacs
2 abdominal sacs
2 caudal thoracic sacs
2 cranial thoracic sacs
1 interclavicular sac
Order of airway branching
primary bronchi - secondary bronchi - parabronchi - atria - infundibuli - air capilaries (site of gas exchange)
Explanation of airflow (2 cycles)
Inhalation 1: Air flows into caudal airsacs
Exhalation 1: Air from caudal sacs flows to parabronchi for gas exchange
Inhalation 2: Air from parabronchi flows to anterior airsacs
Exhalation 2: Air from anterior airsacs flows back out to environment
Anatomical dead space issue
With a longer and wider trachea, dead space increases. Physiological solution is to decrease respiratory frequency
(decreased frequency = decreased dead space b/c less CO2 produced)
Explanation of intra-pulmonary chemoreceptors
- respond to air-borne and blood-borne CO2 levels
- when CO2 increased, decreased firing in afferent fibers (CN10)
- decrease inhibition of rhythm generators in CNS
- respiratory rate increased
Adaptation to high CO2 in nesting birds
- decrease sensitivity of IPC to CO2
- meaning: chemoreceptor will not send signal to increase respiratory rate
(increased respiratory rate would produce more CO2 over time, which is not advantageous in a burrow)
Responses to diving reflex
- bradycardia (slow heart rate)
- induces apnea (stop breathing)
Mechanism of surviving diving
Increase heart rate before diving, which loads myoglobin w/ O2 in preparation for dive
