Flashcards in Fetal and newborn pulmonary physiology Deck (35)
when does alveolar formation begin?
28th week gestation
what are the milestone phases of lung development?
during what week does surfactant start being produced? during which phase of lung development is this?
what events occur during the embryonic phase of lung development?
first segments appear in the 5 lobes
pulmonary vessels have formed
during which phase of lung development can precursors of pneumocytes be discerned in the respiratory sections as cubic epithelium?
during which phase do type I pneumocytes differentiate from type II pneumocytes?
during which phase is amniotic fluid produced by lung epithelium?
at what point can lung maturity be based upon the activity of type II pneumocytes?
from canalicular phase onward
what is the main feature of the saccular phase of lung development?
whole clusters of sacs form on the terminal bronchioli
phase: primary septa contain two networks of capillaries coming from neighboring sacculi
phase: fibroblasts begin to produce extracellular material in the interductal and intersaccular space
by the end of which phase have all generations of conducting and respiratory branches been generated?
the onset of functional maturation of the lung is marked by the appearance of what structures? where are they located?
alveolar type II cells
the ratio of what compounds in amniotic fluid is a measure of fetal lung maturity?
lecithin / sphingomyelin
what happens to the lecithin / sphingomyelin ratio at week 32?
lecithin production increases rapidly
sphingomyelin production decreases
a lecithin / sphingomyelin ratio below what value indicates poor lung maturity?
what are the functions of surfactant specific proteins?
which surfactant specific proteins are critical for surface activity?
what are stimulators of surfactant synthesis in the saccular phase of lung development?
epidermal growth factor
beta adrenergic agonists
what is an inhibitor of surfactant synthesis in the saccular phase of lung development?
what events occur in late fetal life during the alveolar maturation phase of lung development?
increase number and size of alveoli
thinning of CT septa between alveoli
flatter alveolar epithelium
what is the role of the perinatal EPI surge?
activates transepithelial sodium transport to absorb all the fluid in the lungs
perinatal absorption of lung fluid is enhanced by what factors?
thyroid and steroid hormones
alveolar capillary pressure gradient
what is the status of neonatal lung compliance?
low static and dynamic compliance:
low lung compliance
high chest wall compliance
viscous properties of newborn lung tissues
distortion of pliable newborn chest
what is the status of neonatal nasal resistance?
what is the status of neonatal airway resistance?
term infant respiratory function in the first hour of life: lung compliance
term infant respiratory function in the first hour of life: lung resistance
term infant respiratory function in the first hour of life: functional residual capacity
term infant respiratory function in the first hour of life: breathing frequency
term infant respiratory function in the first hour of life: tidal volume
decrease then plateau
term infant respiratory function in the first hour of life: arterial pO2
term infant respiratory function in the first hour of life: arterial pCO2
what happens to the pulmonary arteries : alveoli ratio after birth? what is the effect?
decreasing vascular resistance