embryogenesis 6 Flashcards
what are the germ layers in the lung
endoderm
ectoderm
mesoderm
the endoderm germ layer in the lung form what
Form the majority of conducting systems and alveoli. (with aid of mesoderm)
the ectoderm germ layer in the lung form what
contribute to neural innervation.
the mesoderm germ layer in the lung form what
supporting musculoskeletal components and splanchnic mesoderm form the majority of conducting systems and alveoli.
The lungs are derived from….
lateral plate endoderm
during the phrayngeal arch phase outgrowth of tissue from between which archs
4 th pair
outgrowth of tissue from between the 4th pair of pharyngeal arches is called what
laryngotracheal groove
what does the laryngotracheal groove into and how
the tube splits into left and rightforming a division with a tracheo-oesophageal septum
the laryngotracheal groove spilts into the lung tract and gut tract, which forms left and which forms right
lung - right
gut - left
from the lung diverticulum, it spilts and forms what
lung buds
the lung development is controled by what
retonic acid interacting with the mesenchymal epithelium
if the retinoic acids is blocked what will happen
the lung bud will not form and there will be no branching.
what are the phases of embryonic/ fetal lung development
embryonic, pseudoglandular, canalicular, saccular, alveolar.
note what the right bronchus develops into what four secondary lobular bronchi
cranial, middle , acessory and caudal lobes (humans have no sccessory)
note what the left bronchus develops into what two secondary lobular bronchi
Cranial and caudal
budding and branching is formed from whst signalling paracrine factors
Shh, Wnt, BMP 4
these all impact on FGF10 - this is what efffects the distal mesenchyme (tissue formings)
FGF 10 is important to lung development, why
to much = extensive biudding
too little = no budding
at what phase does the lungs become functional
saccular
at what phase do the lungs become fully functional
alveolar (postnatal)
what does the pseudoglandular phase achive in lung development
Bronchi are coated in cuboidal epithelium, begins to develop ciliated epithelium and secretory cells (first seen in 13 wk for human)
First alveolar cells appear
what does the canalicular phase achive in lung development
Wholewing out material.
an invasion of capillaries into the mesenchymal tissue occurs and the acini develop from the terminal bronchioles. Capillaries surround the acini and thus form the foundation for the later exchange of gases.
From the cubic type II pneumocytes (surfactant production) develop the flattened type I pneumocytes (gas exchange - diffusion)
Sufficient differentiation of the type II pneumocytes into type I pneumocytes and the proliferation of the capillaries into the mesenchymal
what does the Saccular phase achive in lung development
The most peripheral airways form widened “airspaces”, termed saccules.
At the end of each respiratory tract passage smooth-walled sacculi form, coated with type I and type II pneumocytes.
The interstitial space is rich with cells and the proportion of collagen and elastic fibres is still small.
Alveolar Cells Type II (Type II pneumocytes)
begin to secrete surfactant, levels of secretion gradually increase to term.
what does the canalicular phase achive in lung development
At birth, 1/10 of the 300 million alveoli will be present.
Rapid expansion of gas exchange alveoli takes place
Vascular beds (capillaries), lymphatics and innervation are completed to allow functional respiration at birth.
First breath all the liquid in the lungs are expelled
what is the diffrence between type 1 and 2 cubic type pneumocytes.
1 - surfactant production
2 - gas exchange
