Respiratory System Development

Study Notes

Respiratory System Development

Begins as a median outgrowth, the laryngo-tracheal groove, caudal to the 4th pharyngeal pouches
Endoderm lining the groove gives rise to epithelium and glands of the respiratory tract
Surrounding splanchnic mesoderm gives rise to connective tissue, cartilage, and smooth muscles of the respiratory tract

Larynx and Trachea Development

Laryngo-tracheal diverticulum forms by the end of the 4th week, ventral to the caudal part of the foregut
Proximal part remains tubular, opens into the pharynx, and forms the larynx and trachea
Distal end dilates to form a lung bud, which divides to give rise to 2 lateral outgrowths (primary bronchial buds)

Lung Development

Lung buds divide into primary bronchi, which subdivide into secondary bronchi on each side
Segmental bronchi begin to form by the 7th week of development
Respiratory bronchioles develop by the 24th week of development
Additional development and branching of bronchioles occur after birth

Maturation of Lungs

Divided into 4 periods: Pseudoglandular, Canalicular, Saccular, and Alveolar
Pseudoglandular Period: 6th-16th weeks, major elements of lungs have formed, but respiration is not possible
Canalicular Period: 16th-26th weeks, lumina of bronchi and terminal bronchioles become larger, and respiratory bronchioles are formed

Description

This quiz covers the development of the respiratory system, including the formation of the laryngo-tracheal diverticulum and the origin of respiratory tract components. It focuses on the embryonic development of the respiratory system.