Anatomy of respiratory system of poultry birds.

1. Anatomy and Physiology of Respiratory
System
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2. Respiratory System
Comprises of following parts
 Nasal cavity
 larynx
 Syrinx
 Trachea
 Bronchi
 Lungs
 Air sacs
 Pneumatic bones
 Diaphragm

3. Difference between respiratory
system of poultry and mammals
Nasal cavity
 In birds nostrils(nares) are located on the
upper part of the beak / in mammals
nostrils are located on ventral aspect of
nose
 nasal cavity is a single continuous
chamber without septum / divided by a
septum into two chambers in mammals
 Primary function of nasal cavity is as a
respiratory organ / in mammals serve as
both respiratory and olfactory organ

4.  A cornified plate known as operculum
projects from the dorsal border of the
nares.
 In contrast to mammals birds nasal
conchae are arranged in rostrocaudal
rather than dorsoventral sequence
 Cartilaginous lamella arises from
ventral border of nostrils absent in
mammals

5. Larynx
 Larynx manifests as a visible mound in the ventral oropharynx, caudal to
the tongue
 Reflex closure of the larynx prevents entry of foreign material into the
lower airways
 It does not contribute to phonation

6. Trachea
 Trachea conducts the air from nasal cavity and mouth to the
bronchus or bronchi.
 Both birds and mammals have rings however number vary.
 In birds the rings are completely C-shaped but in mammals
incomplete rings
 Trachea kept open and supported by connective tissue and
muscle
Syrinx
 A specialized vocal organ in birds / in mammals larynx is a
vocal cord
 No epiglottis in birds
 The organ of phonation (syrinx) is located at the bifurcation
of trachea rather than near the pharynx (in mammals)

8. Bronchi
Bronchial system of birds consists of three orders of branching before the gas
exchange units are reached.
1. Primary bronchi
2. Secondary bronchi
3. Tertiary bronchi (para bronchi)
Primary bronchi
• Arise from bifurcation of trachea
• has 2 parts
(I) Extra pulmonary bronchus – part within the lungs
(II) Intra pulmonary bronchus – part outside of the lungs

9. (I) Secondary bronchi
(II) Arise from the primary bronchus
(III) Arranges into 4 groups
 laterodorsal secondary bronchi
 7–10 mediodorsal secondary bronchi
 4–7 lateroventral secondary bronchi
 4 medioventral secondary bronchi
Tertiary bronchi (Para bronchi)
• Derived from ramifications of secondary bronchi.

10. Lungs
The left and right avian lungs (plume -sinister and pulmo -dexter) occupy a
dorsal position, either side of the vertebral column.
They are not lobed
Ribs deeply embed the dorsomedial portion of the lungs, forming sulci
costales thus known as tori inter-costales ( lung tissue segments)
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11. Air sacs
Air sacs are deformable, thin-walled cavities attached to the lungs.
Function
 Mechanical ventilation of lungs by acting as a bellows
 Pneumatisation of the skeleton
Eight air sacs are present in the domestic chicken
 An unpaired cervical air sac
 An unpaired clavicular air sac
 Paired cranial thoracic air sacs
 Paired caudal thoracic air sacs
 Paired abdominal air sac

12. Breathing Mechanism