Module 3: Development of the Thorax, Head, and Placenta Flashcards
What are the 3 partitions in the intraembryonic cavity?
Pleural, pericardial, peritoneal
What is the diaphragm?
dome shaped muscle below the heart and lungs that separates the thoracic and peritoneal cavities
What 3 structures fuse to form the diaphragm?
mesenchyme, septum transversum, pleuroperitoneal folds
What direction do the pleuroperitoneal folds grow?
ventrally from the dorsal body wall
what are the pericardial folds?
lateral body wall folds that contain phrenic nerves
How do the pericardial folds grow?
towards each other medially to separate the thoracic cavity into pleural and pericardial cavities
What is the tracheobronchial tree?
system of airways that allow the passage of air into the lungs
What are the component of the tracheobronchial tree in chronological order?
trachea, bronchi, bronchioles, alveoli
When does lung development begin?
day 22
What portion of the primitive gut are the lungs derived from?
the foregut
What are the steps to lung development?
respiratory diverticulum - out pocketing in the ventral wall of the foregut expand in to surrounding splanchnic mesoderm
tracheal buds - diverticulum pinches off the ventral wall forming the trachea and the esophagus, then tracheal buds protrude from the caudal diverticulum
bronchioles - tracheal buds form the right and left primary bronchi and continue to branch to form all major airway structures
When do the alveoli form?
week 16
What is surfactant?
compound that reduces the surface tension between the pulmonary air liquid interface enabling proper expansion of the alveoli and prevents collapse during expiration
When do breathing movements begin?
around week 20/21
What are breathing movements in a fetus?
occur when contractions of the respiratory muscles cause inhalation and expiration of amniotic fluid which help tone the muscle for breathing
How do the lungs get rid of the amniotic fluid during birth?
compression of the thoracic cavity during birth forces much of the liquid to be expelled
What are the pharyngeal arches?
series of externally visible anterior tissue bands deep to the developing brain
What do the pharyngeal arches give rise to?
structures of the head and neck
What do the pharyngeal arches develop from?
lateral plate mesoderm and neural crest cells; mesenchymal core lined externally by ectoderm and internally by endoderm
What are pharyngeal pouches?
endodermal lined pockets that form on the inside of the pharynx between the arches
What does pharyngeal pouch 1 give rise to?
auditory tube and middle ear cavity
What does pharyngeal pouch 2 give rise to?
palatine tonsil
What does pharyngeal pouch 3 give rise to?
inferior parathyroid gland and thymus
What does pharyngeal pouch 4 give rise to?
superior parathyroid gland and ultimobranchial body
