Pulmonary Embryology Flashcards
The _____ is a cartilagenous tube extending from the larynx to the bronchial tubes. Rings of ______ in this structure prevent collapse.
trachea, hyaline cartilage
The ______ is an arrangement of ___ cartilages connected by membranes and ligaments. All of these cartilages are made up hyaline except for _____
larynx, 9, epiglottis
The larynx attaches to the ____ bone _____ [position] and opens into the ______
hyoid bone, superiorly, laryngopharynx
The larynx is _____ continuous with the trachea
inferiorly
What are the three basic functions of the larynx?
provides an airway for breathing, routes food and air, protects vocal cords
The _____ is a _______, dome shaped parition that separates the thoracic from abdominal arteries
diaphragm, musculotendinous
The epithelium of the internal lining of the trachea and lungs is derived from the ______
endoderm
Cartilagenous, muscular and connective tissue of the respiratory system is derived from the _________
sphlancnic mesoderm
The respiratory system develops from the _______ which is an outgrowth from the _____ body wall of the _____ and appears during gestational week ___
respiratory diverticulum, ventral, foregut, 4
The respiratory diverticulum expands _____ and _______ ridges form which separates the _____ from the foregut
caudally, tracheo-esophageal, lung bud
Once the tracheo-esophageal ridges form, the diverticulum is then called the ______ with the _____ portion consisting of the trachea and the _____ portion consisting of the esophagus
tracheo-esophogeal septum, ventral, dorsal
What is the tracheo-esophageal fistula?
an abnormal partitioning of the esophagus and trachea by septum; found in 1/3000 births
86% of tracheo-esophageal fistulas are _____ where the upper esophagus ends in a ______ [artesia], while the lower esophagus forms a fistual with the trachea
type III, blind pouch
The upper esophagus forms fistula in ___ of tracheo-esophageal fistula cases
1%
In ___ of cases of tracheo-esophageal fistula, the esophageal artesia is isolated, whereas in _____ there is no artesia but there is still abnormal communication between the trachea and esophagus
4%, H-type
What is the clinical presentation for tracheo-esophageal fistula?
excessive salivation/drooling; choking/aspiration pneumonia; inability to pass feeding catheter into stomach
What 2 characteristics are seen on an x-ray of a pt with tracheo-esophageal fistula?
dilated upper esophageal pouch; increased air in abdomen/stomach
How is tracheo-esophageal fistula diagnosed?
via bronchoscopy (airway endoscopy)
How does tracheo-esophageal fistula lead to polyhydramnios?
amniotic fluid does not pass into stomach
How does tracheo-esophageal fistula lead to pneumonia?
passage of fluid into trachea
What is one possible cause of tracheal stenosis/agenesis?
vascular compromise to the developing trachea
The muscle and cartilage of the larynx forms from the ______ of which pharyngeal arches?
mesenchyme, 4, 6
True/False: The epiglottis is a flexible, cartilagenous flap over trachea and esophagus that is derived from the 6th pharyngeal arch
FALSE 4
In gestinational week ___, the laryngeal orifice is seen at the ___ pharyngeal pouch
5, 4th
True/False: Besides the epliglottis, the other laryngeal cartilages are derived from the 4th and 6th pharyngeal arches
TRUE
When the mesenchyme of the pharyngeal arches proliferates, the _____ changes from a slit into a ____
laryngeal orifice, T-shape
The mesenchyme from the pharyngeal arches differentiates into what three structures?
thyroid cartilage, cricoid cartilage, arytenoid cartilage
The _______ is the site of vocal cord attachment for speech
arytenoid cartilage
The ______ is the site of muscle attachment for speech and completely encircles the trachea
cricoid cartilage
The ______ is the bulk of the front wall and protects the vocal cords
thyroid cartilage
The epiglottis formed from the 4th pharyngeal arch gives rise to the _____ which is innervated by branches of _____
superior laryngeal nerve, CNX
The arytenoid swellings and vocal cords from 6th pharyngeal arch give rise to the _____ which is innervated by branches of _____
recurrent laryngeal nerve, CNX
Each pharyngeal arch contains what four characteristics?
cartilagenous component, cranial nerve, artery, muscular component
The epiglottis, cuneiform cartilage, and corniculate cartilage become apparent between ______ gestational age
7-10 weeks
The _______ results from the failure of the _______ to develop and allows communication between the ____ larynx and esophagus. It is found in 1/10,000 and 1/20,000 births
congenital laryngeal cleft, tracheo-esophageal septum, posterior
What are three symptoms of congenital laryngeal cleft?
aspiration, choking, weak voice
Describe types 0-4 of congenital laryngeal cleft
type 0 = occult submucosal; type 1 =interarytenoid only; type 2 = partial cricoid; type 3 = complete cricoid +/- cervical trachea; 4=extends into thoracic trachea, up to the carina
In what week of development do the lung buds appear? How many buds are there and how many bronchial buds or lobes?
5th week, 2 lung buds (R and L), there are 2 bronchial buds on left side and 3 on the right side
In the __ week embryo, segments of primitive lobes form. ____ are on right and ____ are on left
6, 10, 8
In the __ week embryo, segments divide further and expand caudolaterally. Then, by the end of the 6th month, there are ____ generations of subdivisions and an additional ___ divisions postnatally
8, 17, 6
During development of the pleural membrane, the bronchial buds “punch” into the ______ which derives from the sphlancnic mesoderm
visceral pleura
The _________ is the space between the pleural and visceral pleura at the point when there is no split between pleural and pericardial cavities
pericardioperitoneal canals
The pericardioperitoneal canals get separated by the ______ which creates the pleural and pericardial cavities
pleuropericardial fold
After the pleural and pericardial cavities are created, the lungs grow and expand into the pleural cavity, which is aided by maturation of the ___
pericardium
The pulmonary arteries grow _____ from the _______ and the branches position themselves next to _____ branches
caudally, aortic sac, bronchial
True/False: all arterial branches are completed by 16 weeks gestational age
True
True/False: arterioles and capillaries stop proliferating at birth
FALSE - keep proliferating for several years after birth
During the ______ which is gestational week _____ period, branching continues to form terminal bronchioles but there is no division yet of terminal into respiratory bronchioles
pseudoglandular, 5-16
During the ______ period which is gestational week ______, the respiratory bronchioles are formed and are lined with _____
canalicular, 16-26, cuboidal epithelium
The respiratory bronchioles divide into _____ during the canalicular period and these end in nascent terminal sacs, which are lined with ________ in contact with capillaries
alveolar ducts, flattened epithelial cells
During the ______ period which is gestational week ____, there is robust formation of the terminal sacs also known as _______
terminal sac period, GW26, primitive alveoli
When does gas exchange begin to occur?
by end of 7th gestational month
During the _______ period, which lasts from _____ to _____, the alveolar epithelium (type I) cells become ____ which allows epithelial-endothelial contacts to be more intimate
alveolar, 8 months, childhood, squamous
Also during the alveolar period, there is formation of ________ which secrete surfactant and are cuboidal
type II alveolar epithelial cells
Surfactant is a ____ that lowers surface tension at interface between ____ and ____. Secretion of this substance increases dramatically in the final gestational month.
phospholipid, air, alveoli
When respiration begins at birth _____ and _____ is absorbed by the alveoli and remains deposited on the inside of ______ membranes
lung fluid, surfactant, type I alveolar cell
How is surfactant secreted by type II alveolar cells of the embryo thought to elicit uterine muscle contraction and labor?
secretion of surfactant into the amnionic fluid activates macrophage which migrate into the uterus and upregulate immune cells –> increases prostaglandin secretion –> uterine muscle contraction and labor
________ is caused by deficiency of surfactant and affects 2% of live newborns and accounts for ___ of newborn death
neonatal respiratory distress syndrome, 20%
Neonatal respiratory distress syndrome leads to low _____ and subsequenct _____ of the lungs
compliance, atelectasis (alveoli collapse)
How does neonatal respiratory distress syndrome lead to hyaline membrane disease?
Labored breathing damages alveolar epithelium —> protein deposition and hyaline changes
What are three causes of neonatal respiratory distress syndrome (NRDS)?
type II cells undeveloped, lack of compression during c-section, maternal diabetes
How does lack of compression during c-section lead to neonatal respiratory distress syndrome?
lack of cortisol –> lack of surfactant
How does maternal diabetes lead to neonate respiratory distress syndrome?
high insulin decreases surfactant
How is neonatal respiratory distress syndrome treated?
with corticosteroids from gw 23-24 and artificial surfactant (endotracheal)
What are the 4 structures involved with diaphragm development?
septum transversum, pleuroperitoneal membranes, dorsal esophageal mesentery, body wall
The septum transversum forms the ____ whereas the pleuroperitoneal membranes fuse with ____ and _____
central tendon, tendon, esophageal mesentery
The dorsal esophageal mesentery becomes _____ of diaphragm muscle
crural portion
The body wall becomes the ____ portion of the diaphragm muscle
costal portion
What are the two types of congenital diaphragmatic hernias?
This birth defect is present in 1/3000 people
Bochdalek type, morgagni type
The Bochdalek type is the most common (80-90%) and most severe and can lead to severe ______. It is ____ and in 85% of cases left-sided. It can be isolated or complex. The abdominal organs move into the _____ and the heart is pushed to the ____
lung hypoplasia, posterolateral, parasternal left chest, right
The Morgangi type is an ____ and ____ defect. There is no significant pulmonary hypoplasia and only mild to no respiratory distress. What happens in this type to the diaphragm?
anterior, parasternal; incomplete muscularization
Describe 2 features of the hypoplastic lung
smaller/hypoplastic airways and alveoli; smaller pulmonary vascular bed
Describe 2 implications of a smaller pulmonary vascular bed in the hypoplastic lung
Increased constriction of pulmonary blood vessels; decreased gas exchange area
What is the principal determinant of lethality in congenital diaphragmatic hernia?
the persistent pulmonary HTN caused by the increased pulmonary vascular resistance as a result of the smaller pulmonary vascular bed
_____ are filled with lung or air and result in dilation of terminal bronchi. These draina poorly and cause chronic infections
congenital lung cysts
True/False: Unilateral lung agenesis is compatible with life
TRUE
In _____ caused by congenital diaphragmmatic hernia or congenital heart disease there is reduced _____
lung hypoplasia, lung volume
What causes the development of ectopic lung lobes?
additional respiratory diverticulum develop off of hindgut independent of main system
Abnormal division of bronchial tree leads to ______ which are of little functional significance
supernumary lobules
