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SGU SVM EMBRYOLOGY: Development of Respiratory System

Terms in this set (23)

What does the respiratory diverticulum derive from?
The ventral wall of the foregut
What is endodermal in the respiratory system?
Epithelium of the larynx, trachea, bronchi, and lungs
What is derived from the splanchnic mesoderm?
The cartilaginous and muscular components
Laryngo-Tracheal Groove
Develops ventrally from the foregut, grows into splanchnic mesoderm below foregut
What occurs when the laryngo-tracheal groove forms the trachea-esophageal septum?
Ridges of mesenchyme proliferate on side of groove to form the septum and divide the foregut into a dorsal and ventral portion
What are the dorsal and ventral portions of the trachea-esophageal septum also known as?
Dorsal
Laryngo-Tracheal Tube
Ventral
Lung Bud
Lung Bud
Extends b/w foregut and heart, and becomes bilobed, these form the left and right principal bronchi
Which species do a third tracheal bronchus develop on the right side?
Ruminants and pigs
Further develops into right cranial lobe, so these species only have 3 lobes on right side
What does the principal bronchi grow and subdivide to create?
Lungs, lobar bronchi, segmental bronchi, and bronchioles
What are alveoli initially formed as?
Solid cords of cuboidal cells
Expand later when lumen of bronchioles enter
What initiates the changes in the respiratory system at birth?
Cessation of umbilical blood flow results in rapid decrease of oxygen and increase of carbon dioxide
This then stimulates respiratory centers in the medulla, to start breathing
What occurs after the onset of inspiration?
Bronchial tree and alveoli expand, maintained by surfactant
Pulmonary vasodilation due to sudden expansion, ductus arteriosus constricts
What is the result of the constriction of the ductus arteriosus?
Blood from pulmonary trunk is now diverted to perfuse the lungs
How is the fluid removed from the lung?
Direct flow to the pharynx and oral cavity
Evaporation into the respired air
Absorption into the pulmonary lymphatics
How are the pleural and pericardial cavities separated?
--As the common cardiac veins grow. mesenchymal tissue surrounding them is the pleuropericardial fold
--The folds grow medially and fuse to form pleuropericardial septum
What does the pleuropericardial septum further grow into?
As the lungs grow laterally into the body wall, septum grows laterally as well to form pericardium of the heart
Malformations
Tracheal Hypoplasia or tracheal stenosis
Tracheal-Esophogeal fistula
Pulmonary Hypoplasia
Tracheal Hypoplasia
Primary defect in cartilage morphogenesis in the English Bulldog
Tracheostomy's-Esophageal Fistula
Improper separation of the caudal portion of the laryngotracheal groove from the foregut
Pulmonary Hypoplasia
Incomplete development of lungs resulting in lower bronchiole, lower alveoli etc.
What is Respiratory Distress Syndrome?
Inability of alveolar epithelial cells to produce enough surfactant to prevent collapse of the alveoli after initial distension with air
What results from respiratory distress syndrome?
--Cerebral hypoxia caused by insufficient respiratory function, seizures commonly occur in foals
--Insufficient volume of blood circulating in the newborn which prevents a normal full expansion of lungs and deprives the CNS of the O2 it needs
What is Barker Foal Syndrome?
During the onset of seizures resulting from cerebral hypoxia, foal may make barking sounds
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