Stevens- Lung Development Flashcards
normal human development is ____ weeks
38 weeks
chance of survival increases with each additional what
week
most common cause of death in extremely preterm babies
acute respiratory failure
phase of development weeks 1-4
embryonic
main events that happen in embryonic phase
primary main bronchi buds form
responsible for developing epithelial airway and tubes
endoderm
responsible for mesenchyme development
mesoderm
5 stages of lung development
embryonic
pseudoglandular
canalicular
saccular
alveolar
4-16 weeks
Pseudoglandular stage
-bronchioles and terminal bronchioles form
-vascular network in mesenchyme
pseudoglandular stage
16-26 weeks
Canalicular stage
respiratory bronchioles form
gas exchange can happen at the end of this stage
canalicular stage
babies born before saccular stage need what to survive
O2
steroids (to make surfactant)
26-36 weeks
Saccular stage
terminal sacs
type II cells secrete surfactant
Saccular stage
cell that produces surfactant (lowering surface tension)
type II pneumocytes
composed of proteins and lipids (DPPC)
surfactant
lowers alveolar surface tension
has antimicrobial properties
surfactant
too little surfactant can lead to what in infants
respiratory distress syndrome (restrictive physiology)
too much surfactant
pulmonary alveolar proteinosis
supplement ___ in preterm infants for air breathing life
surfactant
36 weeks-8 years
Alveolar stage
alveoli increase
type II cell proliferation
Alveolar stage
formed by a process known as secondary septation
alveoli
2 types of cells (interstitial cells) that play a role in septation
lipid fibroblasts
myofibroblasts
make lipids for type II cells so they can make surfactant
lipid fibroblast
essential for secondary septation (important for increasing surface area for gas exchange)
myofibroblast
____develops and aligns with the airways
circulation
Rapid expansion of functional circulation beginning in the _____stage; and circulation becomes continuous here
pseudoglandular stage
development of lung bud relies on communication of what 2 things
epithelium (airways) and mesenchyme (circulation)
fetal O2 is ____ compared to adults
low
low fetal oxygen levels (hypoxia) will promote what
lung development
Babies born prematurely will be exposed to oxygen supplementation and while its necessary to have the O2 supplementation to meet metabolic demands of the body; the high level of O2 can cause impairment of normal vascular development—–this is seen in _____ due to preterm birth
broncho-alveolar dysplasia (broncho-pulmonary dysplasia—BPD)
this is defined as the need for supplemental oxygen beyond 30 days of life
BPD
alveolar simplification
capillary hypoplasia
interstitial cellularity
BPD
hypoxia conditions in the fetus contribute to high ________ in utero
pulmonary vascular tone
fetal circulation has high ___ and low ___
high resistance
low blood flow
the reason the blood is shunted in utero
the resistance in the pulmonary circulation is high and the path of least resistance is to shunt blood from pulmonary to systemic circulation (and lungs not developed)
_____ ventricle is unusually large in fetus compared to adult
R ventricle
____ artery is highly muscularized in fetal circulation compared to adult
pulmonary artery
what decreases minutes after birth
pulmonary vascular resistance (and pressure)
retention of medial hypertrophy of pulmonary a. can lead to what of neonate
pulmonary HTN
