divers exotics bird anatomy

What are the components of the avian respiratory system?

Nasal cavity, choana, larynx, trachea, syrinx, bronchi, parabronchi, lungs, and air sacs.

What are the functions of the avian respiratory system?

Gas exchange, thermoregulation, and vocalization.

Can birds breathe through their nose?

Yes. They also use it for olfaction (smell).

What is open-beak breathing a sign of in birds?

Disease

What causes blocked nostrils in birds?

Hyperkeratosis and hypovitaminosis A.

What diet commonly causes hypovitaminosis A in birds?

High-fat, seed-based diets.

What is the path of air through the avian upper airway?

Nostril, then nasal cavity (conchae), then choana, then larynx.

Which avian paranasal sinus commonly gets infected?

the infraorbital sinus.

What does the nasal salt gland do?

It allows sea birds to drink sea water by excreting excess salt.

What does the avian larynx look like, and where is it?

A slit-like opening at the base of the tongue.

What 2 structures do birds lack compared to mammals?

An epiglottis and a soft palate.

What regulates airflow through the avian larynx?

The rima glottis, using dilator and constrictor muscles.

What is the purpose of the rima glottidis muscles?

o regulate airflow and prevent aspiration.

What are avian tracheal rings like compared to mammals?

they’re complete cartilaginous rings (full O shapes), not C-shaped.

Why does the avian trachea have a greater diameter?

To compensate for its increased length and the increased resistance that comes with it.

Why should you be careful with cuffed endotracheal tubes in birds?

The complete tracheal rings can’t expand, so an inflated cuff can damage the tracheal mucosa

Which birds have a median septum in the trachea?

Penguins

What unusual tracheal shape can some birds have?

It can be long, and even coiled within the sternum.

What is the syrinx?

The avian voice box.

Where is the syrinx usually located?

at the tracheobronchial junction, where the trachea splits into the bronchi.

What is the syrinx made of?

Modified tracheobronchial cartilages with tympaniform membranes.

What is the syrinx a common site for clinically?

Foreign body obstruction and granulomas.

How do avian lungs differ in volume from mammalian lungs?

They have a fixed volume, are more rigid, and don’t change volume during breathing.

Do birds have a diaphragm?

no

What happens to avian lungs when the coelom is opened?

They do NOT collapse

Where does the primary bronchus go in birds?

it runs through the lung and ends in the caudal air sacs.

What is the order of bronchial branching in birds?

Primary bronchus, then secondary bronchi, then tertiary bronchi (parabronchi).

Where does gas exchange occur in birds?

In the tertiary bronchi (parabronchi).

What are the tertiary bronchi also called?

Parabronchi

What factor increases the number of parabronchi in a bird?

Active flight. Birds that fly more have more parabronchi.

How do parabronchi appear on lateral radiographs?

As a honeycomb pattern.

What are the 2 types of parabronchi?

Paleopulmonic and neopulmonic.

What percentage of parabronchi are paleopulmonic?

75% or more.

What type of airflow do paleopulmonic parabronchi have?

Unidirectional (one-way) airflow (PPB)

What percentage of parabronchi are neopulmonic?

Less than 25%.

What type of airflow do neopulmonic parabronchi have?

Bidirectional (two-way) airflow.

Paleopulmonic vs. neopulmonic: which is more common, and how does air flow in each?

Paleopulmonic parabronchi are the majority (≥75%) with unidirectional flow. Neopulmonic parabronchi are the minority (<25%) with bidirectional flow.

Why do birds have higher O₂ demands than mammals?

To fly at speed and at altitude.

How much more efficient is avian gas exchange than mammalian?

About 10× more efficient.

How do avian air capillaries differ from mammalian gas exchange surfaces?

they’re finer and more numerous.

What type of blood flow makes avian gas exchange more efficient?

Cross-current blood flow.

What type of airflow allows continuous gas exchange in birds?

Unidirectional airflow (CGE)

How do rigid lungs help gas exchange in birds?

They provide about 20% more area for gas exchange.

What are the 4 reasons avian gas exchange is so efficient?

1) Finer, more numerous air capillaries. 2) Cross-current blood flow. 3) Unidirectional airflow (continuous exchange). 4) Rigid lungs (about 20% more exchange area).

What is the downside of birds’ highly efficient respiratory system?

Birds are more susceptible to inhaled toxins and infections.

What are 4 structural features of avian air sacs?

They’re distensible, transparent, only 2 cells thick, and extend from the body cavity into the bones.

What percentage of respiratory volume do the air sacs make up?

80%

What is the blood supply of the air sacs like?

Poor

Does gas exchange occur in the air sacs?

no

how many air sacs do birds have in your notes?

8: 3 pairs and 2 singles.

How is each air sac connected to the lung?

By an ostium (opening).

What are the cranial air sacs?

Cervical, clavicular, and cranial thoracic.

What do the cranial air sacs connect to?

The ventral bronchi.

What are the caudal air sacs?

Caudal thoracic and abdominal.

What do the caudal air sacs connect to?

The primary bronchus.

What is the main respiratory function of the air sacs?

They act as bellows, creating unidirectional airflow through the lungs.

How do air sacs help with thermoregulation?

They help dissipate the heat produced during flight.

What are the non-respiratory functions of the air sacs?

Heat dissipation, sound production, and courtship displays.

What are the 3 functions of the air sacs?

1) Bellows for unidirectional airflow. 2) Heat dissipation during flight. 3) Sound production and courtship displays.

Lungs vs. air sacs: which does gas exchange, and which moves air?

The lungs (parabronchi) do gas exchange. The air sacs move air like bellows but do no gas exchange.