Olm Anat. 05: Introduction to the Respiratory System PDF

OLM ANAT. 05: INTRODUCTION TO THE RESPIRATORY SYSTEM Insert Image Here Fundamentals of Organ System Dr. Abass Alhassan, PhD  4.4 Learning Objectives Describe the development of the lung bud and surrounding structures of the pharyngeal foregut Describe the 4 major d...

OLM ANAT. 05: INTRODUCTION TO THE RESPIRATORY SYSTEM Insert Image Here Fundamentals of Organ System Dr. Abass Alhassan, PhD  4.4 Learning Objectives Describe the development of the lung bud and surrounding structures of the pharyngeal foregut Describe the 4 major developmental stages of the lung and their distinctive components of each stage Identify the lobes of the right and left lungs and their bronchopulmonary segments.  Respiratory system Respiratory system does not carry Phary out its physiological function (of nx Lary gas exchange) until after birth. nx Respiratory tract, diaphragm and Trach lungs do form early in embryonic ea development. Bronc Respiratory tract is divided hi anatomically into 2 main parts: Bronchiol es upper respiratory tract, Lun g consisting of the nose, nasal cavity and the pharynx Alve oli lower respiratory tract Diaphragm consisting of the larynx, Development of Lower Respiratory Tract and Lungs Ventral wall of foregut → laryngotracheal groove → laryngotracheal diverticulum Tracheoesophageal fistula/Atresia Hypoplasia of tracheoesophageal septum; Fistula found between trachea and esophagus; Usually accompanied by esophageal atresia.  Bronchial Development Lung Embryology ❖ Distal end of diverticulum divides into right and left lung buds → bronchi and lungs ❖ Undivided part forms the trachea ❖ The opening of diverticulum becomes larynx.  Pseudoglandular Canalicular Stage Stage (5-16 weeks) (16-25 weeks) Terminal Sac Terminal CT Cells Sac Capillari Capillari es es Respirato ry Bronchiol es Terminal Bronchiol e CT CT Terminal/ Conducting Bronchioles  Terminal Sac Alveolar Stage Stage (Birth-8 years) (26 weeks-Birth) Respirato Respirato ry ry Bronchiol Bronchiol e e Terminal Sacs Terminal Bronchiol e Smooth Terminal Muscle Bronchiol Cell e Alveoli Respirato Alveolus ry Capilla al sac period Bronchiol ry eks to birth) e Clinical Correlation Hyaline Membrane Disease HMD is caused by a deficiency or absence of surfactant that is produced by type II pneumocytes. Surfactant is a surface active agent that coats the inside of alveoli to maintain alveolar patency. HMD is prevalent in premature infants (accounts for 50%– hyperaerated alveoli 70% of deaths in premature infants), infants of diabetic mothers, infants who experienced fetal asphyxia or maternofetal hemorrhage (damages type II pneumocytes), and multiple-birth infants. Clinical features include dyspnea, tachypnea, inspiratory retractions of chest wall, expiratory grunting, cyanosis, and nasal flaring. Treatments include administration of betamethasone (a corticosteroid)  Knowledge Check Quiz A 1- day- old child is referred to the clinic with Neonatal Respiratory Distress Syndrome (NRDS). This syndrome is a life- threatening occurrence due to which of the following? A. Constriction of the primary bronchi B. Loss of visceral pleura C. Loss of arterial supply to the terminal bronchi D. Loss of lymphatic drainage of the lung E. Lack of surfactant causing alveoli damage