Embryo- Development of the RS Flashcards
During what week does the development of the Respiratory System commence?
During week 4(4th week of development)
The development of the Respiratory System starts with the development of ….
Lung Bud
Lung Bud or Respiratory Diverticulum
what is it?
is an outgrowth of the ventral wall of the FOREGUT portion of the digestive tract
Lung bud is dependent on the increase of what?
increase of Retonic Acid(RA) produced by the MESODERM
RA(Retonic Acid) causes the upregulation of…
TBX4 which will be expressed on the endoderm of the gut tube
thus… inducing the formation of the LUNG BUD
Lung Bud will turn into lower respiratory structures like?
Trachea
Larynx
Lungs
Bronchi
Epithelium of internal lining of the Trachea, Larynx,Bronchi and Lungs will be made out of ?
Endoderm (Endodermal origin)
What is the cartilageoneous,muscular and connectie tissue components of the Trachea and Lungs made of?
Visceral (Splanchnic) Mesoderm that surrounds the foregut
How is the Lung Bud and the Foregut separated ?
or
How is the intial open communication of the Lung Bud and the Foregut closed up?
by the Tracheoesophageal Ridges
When Tracheoesophageal Ridges fuse and they form…
Tracheoesophageal Septum
which..
divides the foregut into:
Dorsal portion( esophagus)
Ventral portion( trachea and lung buds)
Esophageal Atresia
caused by an abnormal separation of the esophagus and the trachea
(So they can be connected,which is NOT NORMAL)
Tracheoesophageal Fistula
abnormal connection/hole between trachea and esophagus
Type C: Most common. Portion of the esophagus did not develop and produces pouch. lower esophagus connects directly to the trachea
Type D: Portion of the esophagus did not develop and produces pouch. Pouch and lower esophagus connects through the trachea
Internal linning of the larynx originates from…
Endoderm
Larynx forms into….how many arches?
6 pharyngeal arches
* Each arch made out of mesenchyme
Mesenchyme proliferates rapidly… which causes?
laryngeal orifice to change appearance from a sagittal slit into a T shape opening
T shape opening= leads to larynx formation
During week 5 the _________ forms
T shape Laryngeal orifice, which leads to the larynx formation
Cartilage like cricoid, arytenoid,thyroid and muscles originate from…
the mesenchyme of the 4th and 6th pharyngeal arch
Arch 4th and 6th gives us the ability to talk
Endoderm of the 4th and 6th pharyngeal arch form the…
laryngeal epithelium(proliferates and causes temporarly occulsion of the lumen
Endothelium inside the larynx forms into…
Laryngeal ventricles(due to the vacuolization and the recanalization)
lateral ventricles=lateral recesses
Laryngeal ventricles turn into…
Vocal cords( either false or true vocal cords)
False= looks like vocal cords but doesn’t have muscles to act like a normal vocal cord
Laryngeal muscles will be innervated by which nerve?
Cranial Nerve X. VAGUS NERVE
Superior Laryngeal Nerve: innervates 4th pharengeal arch
Recurrent Laryngeal Nerve: innervates 6th pharengeal arch
During separation of the foregut and the lung bud… what is formed?
Trachea is formed.
And lung bud/trachea bifurcates into: 2 Primary Bronchial Buds
During the beginning of week 5…what happens to the broncial buds?
Bronchial buds enlarge to form the RIGHT and LEFT Primary Bronchi
Right Primary bronchi forms…
3 secondary bronchi
Left Primary bronchi forms…
2 secondary bronchi
Right Secondary Bronchi forms…
10 tertiary segmental bronchi
Left Secondary Bronchi forms…
8 tertiary segmental bronchi
Tertiary bronchi create… eventually?
Bronchopulmonary segments of adult lungs
Before bronchial tree is officially done…. what happens during postnatal life?
6 more additional divisions occur during post natal life
Pleuroperitoneal + Pleuropericardial folds separate the pericardioperitoneal canals from the peritoneal and pericardial cavities
and spaces remaining between them form…
Primitive Pleural Cavities
Pleural Cavities divides into…
Visceral Pleura and Parietal Pleura.
visceral pleura=surrounds the outside of the lung (splanchnic mesoderm)
parietal pleura= covers body wall from the inside (somatic mesoderm)
While bronchial tree is developing the lung assumes a more … ____________ position?
More CAUDAL position
By the time of birth bifurcation(carina) is formed opposite to the 4th thoracic vertebra
Caudal position produces: Apex of lung to be shorter and base of lung to be larger
Lungs become Lungs through 4 stages…
What are the 4 stages?
1 Pseudoglandular Stage(week 5-16) causes bronchial bud to divide-> secondary and then tertiary -> and finally terminal bronchioles
#2 Canalicular Stage(week16-26) cause terminal bronchioles to form respiratory bronchioles. Respiratory bronchiles divide into 3-6 alveoli ducts.
#3 Terminal Sac(week 26-birth) causes primitive alveoli to form around alveoli ducts. Pneumocystes type I and II form. Closed contact with capillaries
#4 Alveolar Stage (8month-8years) septa divides primitive alveoli to obtain mature alveoli
At 6th month of development: Pneunomocytes type I and type II form… what to they do?
Pneunomocytes type I: become thinner so that surrounding capillaries can pertrude the the alveolar sac and initiate gas exchange
Pneunomocytestype II: prodcution of surfactant(which reduces the surface tension of the air-blood barrier and allows lungs to expand and fill up with air more easily)
By the 7th month of development… what happens?
sufficient amount of mature alveoli are present so there is a guarantee of gas exchange
Baby born pre-maturely at 7 months can live
Fetal Breathing Movements commence when?
start before birth so that lungs and muscle can learn to work together and stimulate a good coordination for PERFECT development of respiratory system.
Baby aspire amniotic fluid in womb since there is no air in uterus. But at birth, babies first breath causes the amniotic fluid to get reabsorbed by the pulmonary capillaries or expelled through the trachea.
Surfactant gets left in the inner wall if the alveolar membrane
Growth of the Lungs after birth depends on…
depends on the increase amount of respiratory bronchioles and alveoli
APGAR Score is used to determine if baby is borned with any condition
A(appearence) P(pulse rate) G(grimance) A(activity of muscle) and
R- Respiratory effort, classified between 0,1,2
0-absent crying
1-weak crying or wheezing
2-strong cry
Infant Respiratory Distress is…
deficiency in surfactant causes respiratory distress syndrome
thus… health of baby is dependent on the amount of sulfactant baby contains
