Respiratory development begins early in gestation and proceeds through a sequence of branching, maturation, and vascularization. Although the fetus develops breathing movements before birth, gas exchange still depends on the placenta until delivery.
Respiratory development begins at about week 4. Most respiratory structures arise from endoderm, while ectoderm also contributes to the early nasal region.
All flashcards
What is the lung bud?
A dome-shaped structure that bulges from the foregut around week 4 and gives rise to the developing lower respiratory tract.
What structures develop from the laryngotracheal bud?
Its proximal portion becomes the trachea, and its distal end forms bronchial buds that develop into the bronchi and other lower respiratory structures.
When do type II pneumocytes begin producing surfactant?
After respiratory lining cells differentiate into type II pneumocytes, during the period around weeks 16–24. They initially produce only small amounts.
What do fetal breathing movements involve?
Muscle contractions that draw amniotic fluid into the developing lungs and expel it again with mucus and surfactant. They are intermittent and do not perform fetal gas exchange.
When is a full complement of functional alveoli present?
Alveoli continue to form and mature after birth; a full complement of functional alveoli is present at around 8 years of age.
Quiz questions
When does the first inhalation usually occur after birth?Answer: Within about 10 seconds after birth.
What helps expel much of the lung fluid during birth?Answer: Thoracic compression during passage through the birth canal.
What primarily causes respiratory distress syndrome in premature infants?Answer: Insufficient surfactant impairs lung inflation and gas exchange.
When may nasal continuous positive airway pressure (CPAP) be used for an infant?Answer: When spontaneous breathing continues but pressure support is needed.
By approximately what proportion has pulmonary surfactant therapy reduced deaths due to RDS?Answer: About 50 percent.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.