Establishment of the Respiratory System Flashcards
Conducting portion (8)
Nostrils
Nasal cavities
Paranasal sinuses
Pharynx
Larynx
Trachea
Bronchi
Bronchioles.
Gas exchange (4)
Respiratory brochioles
Alveolar ducts
Alveolar sacs
Alveoli
The first recognizable facial structures are the ____ and the paired maxillary and mandibular prominences.
frontonasal prominence
Frontonasal prominence Differentiates into 2:
paired nasal (olfactory) and lens placodes
Ectoderm thickening which appears bilaterally at the rostral end of the frontonasal prominence (nose)
NASAL PLACODE
____ and ____ subsequently develop at each side of the nasal placodes.
Subsequent growth of surrounding medial and lateral nasal processes forms a _____ (bilaterally).
Medial and lateral nasal prominences
nasal pit
- Develops into the primary nasal cavity
- Separated from the primary oral cavity by
the oro-nasal membrane
NASAL PIT
Give rise to alar cartilage of the nose, nasal
bone and lacrimal bone.
LATERAL NASAL PROCESS
- Fuses with the maxillary prominence
- This lays the foundation for formation of the bones of the upper jaw (the maxilla and incisive bones) and the upper lip.
MEDIAL NASAL PROCESS
- Leaves a medial groove, the philtrum
- Carnivores and small ruminants
INCOMPLETE FUSION
- Results in a continuous upper lip
- Horses, cattle, and pigs
COMPLETE FUSION
The maxillary and medial nasal prominences are separated by the _____.
Later, cord develops a lumen and forms the ____.
nasolacrimal groove
nasolacrimal duct
Develops from the dorsal aspect of the
nasal cavity and grows ventrally
NASAL SEPTUM
Grow ventrally from the lateral walls of the
cavity
PALATINE PROCESSES
*SPECIES DIFFERENCES
Each nasal cavity communicates with the
pharynx by a separate opening.
HORSES
*SPECIES DIFFERENCES
Both nasal cavities share a common
opening to the nasopharynx
OTHER DOMESTIC ANIMALS
- Rostral two-thirds
- Intramembranous ossification
HARD PALATE
Develops caudally from the mesenchyme
covered with ectoderm
SOFT PALATE
- Formed from the processes extending from the lateral aspect of the developing
nasal cavity. - Endochondral ossification transforms this into scroll-like structures.
conchae
- Develop lateral to the nasal septum in the floor of the rostral region of the nasal cavities.
- Cranial ends open into the incisive ducts and the caudal ends of the tube-like organs.
Vomeronasal organ
Development commences when neural crest‐ derived mesenchymal cells migrate into the developing head and neck regions and form discrete aggregations.
PHARYNGEAL ARCHES
Undergoes atrophy
FIFTH ARCH
Fuses with the fourth arch, forming a fourth–sixth arch complex.
SIXTH ARCH
*Larynx
In the cranial portion of the foregut just caudal to the developing pharynx, an internal ____ forms and deepens.
laryngo- tracheal groove
*Larynx
Externally, the developing oesophagus becomes separated from the larynx and trachea by the _____
tracheo-oesophageal groove
*Larynx
Internally, further development of the external groove results in the formation of the ____ defining the respiratory diverticulum.
tracheo-oesophageal septum
*Larynx
The septum separates a ____ from the esophagus.
laryngotracheal tube
*Larynx
The wall of the larynx originates from growth of ____ and ____
bilateral laryngeal swellings (future arytenoid, thyroid & cricoid cartilages)
and
rostral epiglottal swelling.
*Larynx
As the laryngeal cartilages and muscles develop, the ____ are formed.
vocal folds
*Larynx
In the horse and dog, and to a minor degree in pigs, the endodermal epithelium forms a lateral outpocketing resulting in the _____
laryngeal ventricles
*Larynx
In the process, the well-defined ____ are formed rostral to the vocal folds in the horse and the dog.
vestibular folds
____ grows caudally into splanchnic mesoderm located ventral to the pharynx
Laryngotracheal tube
*Trachea & bronchi
The blind, caudal end of the tube develops ____ which grows to form the future _____.
bi-lobed bronchial buds
principal bronchi
*Trachea & bronchi
Outgrowths of each principal bronchus form future _____.
lobar bronchi
*Trachea & bronchi
Each of which gives rise to outgrowths that
become future _____.
segmental bronchi
The smallest branches are
bronchioles
- Represent the termination of the exclusively conducting portion of the respiratory system
- Subdivides into two or more respiratory
bronchioles
TERMINAL BRONCHIOLES
- Transitional zones between the conducting and respiratory regions of the respiratory system
- Present in humans and carnivores
- Give off a number of alveolar ducts from
which alveolar sacs and alveoli arise.
RESPIRATORY BRONCHIOLES
The development of the bronchi and lungs can be divided into sequential periods (3)
Embryonic period
Fetal period (Pseudo-glandular, canalicular, saccular and alveolar periods)
Postnatal period
When the primordium of the bronchi and
lungs is formed
EMBRYONIC PERIOD
When the ramified bronchi are formed and
the preliminary structures for gas exchange
are established
FETAL PERIOD
When the definitive structures for gas
exchange, the alveoli, are developed and
the lungs assume their adult form.
POSTNATAL PERIOD
Characterized by the extensive formation
of the bronchial tree which is a
compound tubuloalveolar pattern of
airways and terminal buds
PSEUDOGLANDULAR STAGE
Characterized by the establishment of
intimate juxtaposition of capillaries and
lung parenchyma (composed of the
bronchioles and alveoli)
CANALICULAR STAGE
Characterized by the formation of the
blind saccules as a result of the terminal
branching of the air conducting system.
SACCULAR STAGE
Establishes the blood – air relationship. The
intimate position of the capillaries and the
alveoli facilitates the exchange of gases (O2 and CO2)
ALVEOLAR STAGE
The endodermal epithelium in the developing alveoli differentiates into:
- Squamous type I alveolar cells
- Cuboidal type II alveolar cells-
cover most of the alveolar surface
Squamous type I alveolar cells-
specialize in the production of surfactant
Cuboidal type II alveolar cells-
- Results from a partial persistence of the
laryngotracheal groove. - Causes refluxing of feed through the upper respiratory tract, and inhalation pneumonia.
TRACHEOESOPHAGEAL FISTULA
Associated with congenital diaphragmatic hernia with the herniated abdominal organs in the thoracic cavity interfering with pulmonary growth.
PULMONARY HYPOPLASIA
- Result from a lack of production of pulmonary surfactant
- Gasping of the newborn is a sign of its presence.
BARKER FOAL SYNDROME: HYALIN DISEASE
