Development of repiratory system By Adhish Gautam
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The document summarizes the development of the respiratory system from the formation of lung buds in a 4 week old embryo to the development of surfactant. Key events include the outgrowth of lung buds from the foregut mediated by retinoic acid, the separation of the trachea and esophagus by the tracheoesophageal septum, the formation and branching of the bronchi and expansion of the lungs, and the later development of surfactant important for premature infants. Abnormalities in partitioning like tracheoesophageal fistulas can occur.
![FURTHER
DEVELOPMENT
• Subsequent growth in caudal and lateral directions, the
lung buds expand into the body cavity .
• The spaces for the lungs, which are the
pericardioperitoneal canals, are narrow.
• The mesoderm[covers outside of the lung] develops into
the visceral pleura.
• The somatic mesoderm layer[covering the body wall
from the inside] becomes the parietal pleura
• The space between the parietal and visceral pleura is
the pleural cavity .](https://image.slidesharecdn.com/developmentofrepiratorysystem-141117143532-conversion-gate01/85/Development-of-repiratory-system-By-Adhish-Gautam-14-320.jpg)
Development of repiratory system By Adhish Gautam
- 1. DEVELOPMENT OF THE RESPIRATORY SYSTEM Name- Adhish Gautam Group-216
- 2. FORMATION OF THE LUNG BUDS • Embryo is 4 weeks old • respiratory diverticulum (lung bud) appears as an outgrowth from the ventral wall of the foregut . • Dependent upon: retinoic acid (RA) produced by adjacent mesoderm. • Epithelium of the internal lining of the larynx, trachea; bronchi; lungs, is Endoderm • The cartilaginous; muscular,; connective tissue components of the trachea; lungs are splanchnic mesoderm ( that surrounds the foregut)
- 3. A Embryo of approximately 25 days' gestation showing the relation of the respiratory diverticulum to the heart, stomach, and liver. B. Sagittal section through the cephalic end of a 5-week embryo showing the openings of the pharyngeal pouches and the laryngotracheal orifice.
- 4. FORMATION OF THE LUNG BUDS -2 • The diverticulum expands caudally, and two longitudinal ridges, the tracheoesophageal ridges, separate it from the foregut. • These ridges fuse to form the tracheoesophageal septum • The respiratory primordium communicates with the pharynx through the laryngeal orifice • Foregut Divides into: 1) Dorsal portion: Oesophagus. 2) Ventral portion: Trachea & Lung Buds.
- 5. • A-C. Successive stages in development of the respiratory diverticulum showing the tracheoesophageal ridges and formation of the septum, splitting the foregut into esophagus and trachea with lung buds. • D. The ventral portion of the pharynx seen from above showing the laryngeal orifice and surrounding swelling.
- 6. TRACHEOESOPHAGEAL FISTULAS (TEFS) • Abnormalities in partitioning of the esophagus and trachea by the tracheoesophageal septum ensuing Esophageal Atresia with or w/o TEFs. • Approx. 1/3,000 births • Blind pouch and the lower segment forming a fistula with the trachea (90% of cases) • Isolated Oesophageal Atresia • H-type TEF without oesophageal Atresia
- 7. • A. most frequent abnormality (90% of cases) occurs with the upper oesophagus ending in a blind pouch and the lower segment forming a fistula with the trachea. • B. Isolated oesophageal atresia (4% of cases). • C. H-type tracheoesophageal fistula (4% of cases). • D,E. Other variations (each 1% of cases).
- 8. BUT THESE ABNORMALITIES ARE ASSOCIATED WITH OTHER BIRTH DEFECTS • Including cardiac abnormalities (33% of cases) • TEFs are a component of the VACTERL Group: • Vertebral anomalies • Anal Atresia • Cardiac Defects • Tracheoesophageal Fistula • Esophageal Atresia, • Renal Anomalies • Limb Defects
- 9. • A, Tracheoesophageal fistula (TEF) in a 17-week male fetus. The upper esophageal segment ends blindly (pointer). • B, Contrast radiograph of a newborn infant with TEF. Note the communication (arrow) between the esophagus (E) and trachea (T).
- 10. LARYNX • Internal lining: originates from endoderm. • Cartilages; muscles originate from mesenchyme of the 4th & 6th pharyngeal arches. • Laryngeal orifice changes from a sagittal slit to a T-shaped opening. • Caracteristic adult shape of the laryngeal orifice can be recognized when mesenchyme of the two arches transforms into the thyroid; cricoid; arytenoid cartilages.
- 11. • Laryngeal orifice and surrounding swellings at successive stages of development: • A. 6 weeks. • B. 12 weeks
- 12. TRACHEA & BRONCHI & LUNGS • The bronchial buds forms • 5th week, each of these buds enlarges to form right and left main bronchi. • The right forms three secondary bronchi. • The left forms two.
- 13. • Stages in development of the trachea and lungs: • A. 5 weeks. • B. 6 weeks. • C. 8 weeks
- 14. FURTHER DEVELOPMENT • Subsequent growth in caudal and lateral directions, the lung buds expand into the body cavity . • The spaces for the lungs, which are the pericardioperitoneal canals, are narrow. • The mesoderm[covers outside of the lung] develops into the visceral pleura. • The somatic mesoderm layer[covering the body wall from the inside] becomes the parietal pleura • The space between the parietal and visceral pleura is the pleural cavity .
- 15. • Expansion of the lung buds into the pericardioperitoneal canals. At this stage, the canals are in communication with the peritoneal and pericardial cavities. • A. Ventral view of lung buds. • B. Transverse section through the lung buds showing the pleuropericardial folds that will divide the thoracic portion of the body cavity into the pleural and pericardial cavities.
- 16. • pericardioperitoneal canals separate from the pericardial and peritoneal cavities, • the lungs expand in the pleural cavities. • Note the visceral and parietal pleura and definitive pleural cavity. The visceral pleura extends between the lobes of the lungs.
- 17. SURFACTANT • Important for survival of the premature infant. • When insufficient, the air-water (blood) surface membrane tension becomes high, bringing great risk that alveoli will collapse during expiration. • Resulting in respiratory distress syndrome (RDS) • Common cause of death in the premature infant.
- 18. THE END
Editor's Notes
- #3: Splanchnic: Relating to or affecting the viscera.
- #5: Primordioum: An organ in its earliest stage of development; the foundation for subsequent development.
- #7: Fistula: An abnormal passage leading from a suppurating cavity to the body surface. Atresia: An abnormal condition in which a normal opening or tube in the body (as the urethra) is closed or absent.
- #8: A complication of some TEFs is polyhydramnios, since in some types of TEF, amniotic fluid does not pass to the stomach and intestines. Also, gastric contents and/or amniotic fluid at birth may enter the trachea through a fistula, causing pneumonitis and pneumonia
- #11: Laryngeal orifice changes shape result of rapid growth of mesenchyme. Thyroid: A gland located near the base of the neck. Arytenoid cartilages: Either of two small cartilages at the back of the larynx to which the vocal folds are attached. The cricoid cartilage: A complete ring cartilage around the trachea.