DEVELOPMENT OF RESPIRATORY SYSTEM NOTES PDF

DEVELOPMENT OF RESPIRATORY SYSTEM All parts of the body develop from one of three layers: Internal: Endoderm- Forms the epithelium of the airway. External: Ectoderm- Plays a minor role in development. Middle: Mesoderm- Develops into cartilage, muscles, and lung tissue. Respiratory system develops...

DEVELOPMENT OF RESPIRATORY SYSTEM All parts of the body develop from one of three layers: Internal: Endoderm- Forms the epithelium of the airway. External: Ectoderm- Plays a minor role in development. Middle: Mesoderm- Develops into cartilage, muscles, and lung tissue. Respiratory system develops in the 4th week of intrauterine life Stages of Lung Development:  1- Embryonic Stage (4th - 7th week): Clinical Condition: Tracheoesophageal fistula (TEF) occurs 2- Pseudoglandular Stage (5th - 17th week): Major airway branching occurs, forming bronchi, bronchioles, and terminal bronchioles. 3- Canalicular Stage (16th - 25th week): Type I cells → Gas exchange. Type II cells → Begin surfactant production at 20 weeks Clinical Condition: Neonatal Respiratory Distress Syndrome (NRDS) occurs 4- Saccular Stage (24 weeks - birth): Formation of primordial alveoli (terminal sacs). 5- Alveolar Stage (32 weeks - 8 years) Development of the Pleura: Visceral pleura: Derived from splanchnic mesoderm (autonomic nerve supply). Parietal pleura: Derived from somatic mesoderm (somatic nerve supply). Congenital Anomalies of the Lungs:  Agenesis: Complete absence of lung development. Hypoplasia: Underdeveloped lung. Lobar variations: Abnormal number of lung lobes. Accessory lung lobes: Extra lobes arising from trachea/esophagus. Congenital lung cysts: Cystic formations within lung tissue. gut tube: The gut tube is formed during week 3-4 The tube is divided into: Foregut, Midgut and Hindgut.