development of respiratory system
TRANSCRIPT
Development of Respiratory System
الرحمن الله بسمالرحيم
Respiratory system
UpperRespiratory
system
LowerRespiratory
system
Nose Pharynx Larynx TracheaBronchi Lungs
Prof. Mohamed AutifiProf. Mohamed Autifi
The lower respiratory system develops as Median laryngo-laryngo-tracheal groovetracheal groove in the floor of pharynx between the 6th pharyngeal arches(26th – 27th day)
Prof. Mohamed AutifiProf. Mohamed Autifi
Laryngo-tracheal groove deepens ➪ laryngo-tracheal diverticulum(respiratory diverticulum)The edges of it fuse ➪ oesophago-tracheal septum, which converts the groove into laryngo-tracheal tube, separates it dorsally from oesophagus
Prof. Mohamed AutifiProf. Mohamed Autifi
The cranial part of the laryngotracheal tube becomes the larynx which opens into the pharynx by laryngeal orifice.
The caudal part separates from the related part of the foregut (oesophagus) and divides into the two principle bronchi.
Each bronchus is divided into 2ry and then 3ry bronchial buds and surrounded by a mesodermal mass and is called the lung bud.
Prof. Mohamed AutifiProf. Mohamed Autifi
The cartilages and muscles of larynx develop mainly from the mesoderm of the 4th and 6th pharyngeal arches.
The cartilages and muscles of the trachea and bronchi develop from the splanchnic mesoderm which surround the laryngo-tracheal tube.
Each lung bud branches into bronchi, bronchioles and alveoli of the lung.
The surrounding mesoderm forms the stroma and blood vessels of the lung.
The pleura is formed a part of intraembryonic coelom.
Prof. Mohamed AutifiProf. Mohamed Autifi
Cartilages:Cartilages:Epiglottis: from the caudal part of hypobranchial
eminence.The rest of the cartilages: from 4th and 6th arch.
Muscles:Muscles:Cricothyroid : from the 4th pharyngeal arch.Other muscles: from the 6th pharyngeal arch.
Mucous membrane:Mucous membrane:Supraglottic area: from the 4th pharyngeal arch
(supplied by superior laryngeal nerve).Infraglottic area: from the 6th pharyngeal arch
(supplied by recurrent laryngeal nerve).Prof. Mohamed AutifiProf. Mohamed Autifi
Congenital anomalies of lungsCongenital anomalies of lungs::
1. Agenesis of one or both lungs: due to failure of
development of lung buds.2. Accessory lung lobes: due to additional
branching of stem of lung bud.3. Abnormal division of bronchial tree: leading to super-numerary lobules. 4. Ectopic lung lobes: arise from trachea or oesophagus, due to abnormal budding.5. Congenital cysts of the lung: due to dilation
of terminal or larger bronchi. 6. Respiratory distress syndrome: failure of the
alveoli to ventilate due to absence of surfactant.
Prof. Mohamed AutifiProf. Mohamed Autifi
6. Tracheo-oesophageal fistula:
due to incomplete fusion of the lips of laryngo- tracheal groove.
Prof. Mohamed AutifiProf. Mohamed Autifi