Respiratory System Development Flashcards
What are fetal breathing movements?
What else is required w/ them for normal lung development?
priming lungs for breathing - breath in amniotic fluid
need adequate space for thoracic growth
adequate amniotic fluid volume
How does hyaline membrane disease present?
What causes it?
ground glass appearance of lungs in chest x ray
occurs bc of lack of surfactant in terminal sac stage
When do secondary bronchi form?
week 6
At what point do you have all your bronchopulmonary segments to the terminal bronchioles?
How many orders of branches are there?
24 weeks
17 orders
What and when happens in pseudglandular lung development?
5-17 weeks
terminal bronchioles formed
connective tissue from splanchnic mesoderm formed
capillaries far away from bronchioles
can’t survive if you only get to this point
When do primary brochial buds form?
week 5
What are the two groups of people whose lungs develop fastest?
african americans
females
(caucasian males develop the slowest)
What causes congenital diaphragmatic hernia?
What is the other name for it?
septum transversum and pleuroperitoneal folds do not fuse
foramen of bochdalek
When/what happens in alveolar development?
32 weeks - 8 years
alveolocapillary membrane formed
primitive alveoli start to mature - 90% of mature alveoli formed after birth
most at 3 yrs, don’t finish until 8 yrs
What are laryngeal webs?
tissue btw vocal folds = incomplete atresia
usually present in infancy w/ respiratory stress and stridor
caused by failure of recanilization
What canals do bronchial buds grow into?
pericrdial-peritoneal canals
When is the tracheoesophageal septum formed?
week 5
What are signs of respiratory distress in an infant?
tachypnea nasal flaring suprasternal, intercostal, or subcostal retractions grunting cyanosis
What does the primitive pharynx and respiratory diverticulum form from?
endoderm from 6th arch
What is oligohydramnios?
What does it cause?
too little amniotic fluid
severe cases –> retards lung development –> pulmonary hypoplasia
When do tertiary bronchi form?
How many are there?
week 7
10 right
9 left
What is the laryngotracheal diverticulum?
Bud of endoderm that is the early trachea
How many secondary bronchi are there?
3 on right: superior, middle, inferior
2 on left: superior, inferior
Oligohydramnios at what stage significantly increases risk of pulmonary hypoplasia?
oliogohyramnios prior to 26 weeks
When/what happens in canalicular lung development?
16-25 weeks
vessels are much closer to terminal sacs now
primordial alveolar ducts have formed from respiratory bronchioles –> terminal sacs
can survive w/ medical intervention
What is laryngomalacia?
collapse of the supraglottic structures during inspiration = most common congenital anomaly of the larynx
mechanism unknown
How does congenital diaphragmatic hernia present?
will see intestines in thorax w/ heart pushed over to the right
barrel-shaped thorax
abdomen scaphoid shaped
absence of breath sounds ipsilaterally
What is recanalization and when does it occur in the larynx?
sequence of apoptosis that allows the endodermal proliferation to turn into a tube again –> allows for laryngeal ventricals and vocal and vestibular folds
10th week
When is surfactant detectible in amniotic fluid?
starting at week 25
How many arytenoid swellings are there?
1, 2, 3, 4, 5 disappears, 6
What is the hypobranchial eminence?
comes from arytenoid arch 4 –> turns into epiglottis
What are the tracheoesophageal folds and septum?
folds are the first bit of endoderm that separate the growing trachea and esophagus (coronal plane) –> once grown together = tracheoesophageal septum
What is laryngeal atresia?
failure of recanilization –> larynx is completely closed
What is the most common kind of tracheoesophageal fistula?
esophageal atresia = blind end esophagus
84% of cases are this
What are the 2 types of Tracheoesophageal fistula?
esophageal atresia = blind end esophagus
trachoesophageal fistula = abnormal passage btw trachea and esophagus
What are the arytenoid swellings made of?
What do they turn into?
neural crest covered in endoderm
turn into cartilage
What neonatal condition can be a risk factor for TE fistula?
polyhydramnios (too much amniotic fluid)
What general part of the lung forms first?
superior part
When/what happens in terminal sac lung development?
24 weeks - birth type I and II pneumocytes differentiate surfactant now produced lymphatic capillaries developed will survive
How is intra-alveolar fluid cleared at birth?
by pressure on thorax during vaginal delivery –> out mouth and nose
into pulmonary capillaries, arteries, and veins
into lymphatics
What are congenital lung cysts filled with?
Why do we think they form?
air or fluid - looks like honeycomb on x ray
thought to be bc of disturbance in bronchial dev during late fetal life
What causes a TE fistula?
When would it occur?
problem w/ tracheal esophageal folds
week 5
What are the 4 stages of lung development?
- pseudoglandular (5-17 weeks)
- canalicular (16-25 weeks)
- terminal sac (24 weeks - birth)
- alveolar (32 weeks - 8 years)
