Respiratory Embryology Flashcards
median outgrowth found in floor of the primitive pharynx
laryngotracheal groove
laryngotracheal groove goes on to form the
laryngotracheal diverticulum (lung bud)
the _____ end of the diverticulum enlarges to form the respiratory bud
distal end
the bud grows ventrocaudally and bifurcates at __ dpf
26-28 dpf
branching pattern of the lung is organized and regulated by what tissue layer
mesoderm induces endoderm to branch
by week 5, the primary bronchial buds branch to form
the secondary bronchial buds
how many orders of airways form after birth?
7 orders
by 24 weeks, the bronchopulmonary segments have formed (3)
segmental bronchi + mesenchyme
17 orders of branching have occured
respiratory bronchioles have formed
lungs are considered pseudoglandular at weeks __ - __
all major elements of the lung have formed except those involved in __________
Looks like _________
pseudoglandular 5-17 weeks
all elements except those involved with gas exchange
looks like exocrine gland
fetus cannot survive
lungs are considered canalicular at weeks __ - ___
what primordial structures are present?
weeks 16-25
primordial alveolar and sacs & respiratory bronchioles present
vascularization
overlaps pseudoglandular stage
can survive? maybe?
between ___ weeks and ____ - the lungs are in the terminal sac phase
_________ can occur because numerous ______ have formed
24 weeks to birth
gas exchange can occur because numerous alveoli have formed (aka survivable)
thin epithelium with increased vascularization
Type 1 pneumocytes
Type II pneumocytes producing surfactant
from 32 weeks to 8 years, the lungs are considered ________
alveolar
primitive alveoli form more primitive alveoli –> eventually mature
approximately __ % of mature alveoli develop postnatally
95%
the splanchnic mesoderm contributes which layer of pleura
visceral pleura
the thoracic body wall becomes lined with what layer of pleura
parietal pleura
trachea develops at the proximal end of the
tracheoesophageal ridge
trachea is formed from ______ and ______ mesoderm
endoderm and splanchnic mesoderm (outer layer)
esophageal atresia is also known as
blind esophagus - pouch structure that doesnt go anywhere else
tracheoesophageal fistula
abnormal connection between trachea and esophagus
Failure of foregut endoderm to proliferate rapidly enough in relation to the rest of the embryo could result in either
esophageal atresia
tracheoesophageal fistula
complete absence of a lung or a lobe and accompanying bronchi
pulmonary agenesis typically unilateral (bilateral would not survive) respiratory bud fails to separate into R/L bronchial buds
fetal breathing movements
essential for normal lung development
conditions respiratory muscles
used to monitor survival
Aspirate amniotic fluid - stimulates lung development
amniotic fluid is cleared from fetal lungs by
1) pressure on fetal thorax during vaginal delivery
2) pulmonary capillaries, AV
3) lymphatics
pulmonary hypoplasia can result from
too little amniotic fluid (oligohydramnios)
reduced lung size because decreased hydraulic pressure on lungs, affecting stretch receptors and lung growth
pulmonary hypoplasia
Respiratory distress is mainly caused by
surfactant deficiency - lungs are under-inflated
rapid, labored breathing that develops shortly after birth with tachypnea, nasal flaring, suprasternal, intercostal, or subcostal retractions, grunting and cyanosis is known as
respiratory distress syndrome
disturbances in bronchial development during late fetal life can result in fluid/air filled structures known as
congenital lung cysts
the intraembryonic coelom forms during week __
the cranial region represents the future ______ cavity
the caudal region represents the future ___ and ___ cavities
week 4
cranial region –> pericardial
Caudal region –> pleural and peritoneal
head folding reshapes the ________ coelom, causing the primitive pericardial cavity to move, placing it cranially to the ____
reshapes the intraembryonic coelom
now located cranially to septum transversum
