Embryology Of Trachea, Bronchi, Lungs Flashcards
Development of the trachea, bronchi and lungs
The lower respiratory organs i.e. _____,____,___,____ begin to form during the ______ week
larynx, trachea, bronchi and lungs
fourth
The respiratory primordium appears as a ______ from the (ventral or Dorsal?) wall of the _____- the ______________
median outgrowth
Ventral
foregut
laryngotracheal groove
- By the end of 4th week, the laryngotracheal groove has __ginated to form a _____-like structure called the ________
- This would _____ and is invested with ______ mesenchyme and its (proximal or distal?) end enlarges to form a ______-shaped _____
eva
pouch
respiratory diverticulum
elongate
splanchnic; distal
globular
respiratory bud
Soon 2 longitudinal ridges separate the laryngotracheal groove from the foregut- the __________
- Subsequently the 2 ridges fuse to form the _______
- Dividing the foregut into a ventral part- __________ and a dorsal part (primordium of _________ and _______ )
tracheoesophageal ridges
tracheoesophageal septum
laryngotracheal tube
oropharynx and esophaus
After formation of the tracheoesophageal septum , the laryngotracheal tube separates from the foregut and forms the;
➢ ______
➢The __________
Trachea
bronchial (lung) buds.
Development of Trachea
- The endodermal lining of the laryngotracheal tube differentiates into the ______ and ____ of the trachea and the ______
- The cartilages, CT, and muscles of the trachea are derived from the __________________________________
epithelium and glands; pulmonary epithelium
splanchnic mesenchyme surrounding the laryngotracheal tube
DEVELOPMENT OF THE BRONCHI
•The respiratory bud that developed at the (cranial or caudal ?) end of _______ during the 4th week divides into two outpouchings – _______
- These endodermal buds grow (medially or laterally?) into the ______ canals
- Together with the surrounding splanchnic mesenchyme, the bronchial buds differentiate into ____ and their ramifications in the lungs
Caudal
laryngotracheal tube
pry bronchial buds.
Laterally
pericardioperitoneal
bronchi
pericardioperitoneal canals is the primordia of the _________
pleural cavities
_____ week- each of the bud enlarge to form the main or principal bronchi.
•The main bronchi subdivides into ____ bronchi that divides into _____ bronchi around the ____ week.
5TH
lobar
segmental
7th
Each segmental bronchus with its surrounding mass of mesenchyme is the primordium of a ________
bronchopulmonary segment
By ___ weeks respiratory bronchioles have developed
24
The lungs acquire a layer of _____ pleura from the splanchnic mesoderm and a layer of _____ pleura from the somatic mesoderm
•Space btw the two layers is ????
visceral
parietal
pleural cavity
Maturation of the lungs is divided into five periods
•_______ period
- _________ period
- ________ period
- _______ period
- _________ period
Embryonic
Pseudoglandular
Canalicular
Terminal sac
Alveolar
EMBRYONIC PERIOD of lung maturation
●It occurs between the ___-___ week of gestation.
•During this period the tracheobronchial bud divides to form the proximal airways to the level of the ___________
4th to 6th
segmental bronchi.
PSEUDOGLANDULAR PERIOD of lung maturation
__-___WEEKS
- The ___ resembles an ______ during this period.
- Branching has continued to form ____ bronchioles.
- By the end of this period , all major elements of the lung have formed, except those involved with ______
6- 17
terminal bronchiole; exocrine gland
terminal
gas exchange.
Presence of respiratory bronchioles or alveoli in PSEUDOGLANDULAR PERIOD of lung maturation
T/F
F
No respiratory bronchioles or alveoli are present.
CANNALICULAR PERIOD of lung maturation
___-___WEEKS
• Each terminal bronchioles divides into two or more ________ that divides into __to__ ______ that end in ______ (primitive ____)
•The tissues become more ____ as _____ develop.
17-26
respiratory bronchioles
3 to 6
alveolar ducts.
terminal sacs
alveoli
vascular; capillaries
TERMINAL SAC PERIOD of lung maturation
from _____ to _____
•Many more _____ (primitive alveoli) develops and their epithelium becomes very (thin or thick ?)
•Capillaries begin to ____ into ________
•The intimate contact between ______ and _______ cells establishes the ______.
24 weeks to birth
terminal sacs
Thin
bulge; these developing alveoli.
epithelial and endothelial
blood-air barrier
blood-air barrier permits adequate gas exchange for survival of the foetus if it is born prematurely
T/F
T
TERMINAL SAC PERIOD of lung maturation
•By ___ weeks, the terminal sacs are lined mainly by ____ epithelial cells of __dermal origin
➢Type I alveolar cells or pneumocytes- _______ function.
➢Type II alveolar cells — ___________ function
24
squamous
endo
gas exchange
which secrete pulmonary surfactant.
Sufactant production begins in the ____ week and ___eases during the ____ weeks of pregnancy.
20th
Incr
last 2
fetuses born prematurely at 24-26 wks after fertilization may survive intensive care but may suffer respiratory distress because of _____
•Survival has improved with the use of ___________
surfactant deficiency
antenatal corticosteroids
ALVEOLAR PERIOD of lung maturation
______ PERIOD TO _____
•Structures analogous to alveoli are present at ____ weeks of gestation
•At the beginning of the alveolar period, each respiratory bronchiole terminates in a cluster of (thin or thick?) -walled terminal sacs.
•Characteristic mature alveoli do not form until _____
LATE FETAL; CHILDHOOD
32
Thin
after birth
about 95% of alveoli develop prenatally
T/F
F
about 95% of alveoli develop postnatally
TRACHEOESOPHAGEAL FISTULA
•It is an abnormal connection between the _____ and the ____.
•It occurs due to improper division of the ____ by the ____________
lower oesophagus
trachea
foregut
tracheoesophageal septum
unilateral pulmonary agenesis is incompatible with life
T/F
F
It is
Accessory lung-
(Common or uncommon?)
always located at the ___ of the ____
Uncommon
base
left lung
