Embryology 3 Flashcards
Where does the trachea develop from
from the layrnotracheal groove on ventral wall of the foregut - oesophagus
What separates the trachea and the oesophagus
oseophaotracheal septum
How many weeks gestation until the trachea and lungs full develop
4 weeks
8 weeks
After the formation of the lung buds what do they go on to invaginate
and what surrounds them
Invaginate visceral mesoderm
surrounded by pleural cavity and parietal pleura
What does the splanchnic and somatic mesoderm in the lungs go on to develop
visceral pleura - splanchnic
parietal pleura - somatic
What is the 5 differentiation stages of lung buds development
Embryonic Pseuglandular Canaicular saccular alveolar
What is the morphology of the lung buds
elongate
widen
form sacs
then finally bud into tiny alveoli
Where does the sept transverse develop between
the thorax and the abdomen
What is the septum transversums initially location
and what does it bring down with it in the formation of the diaphragm
opposite c3 - c5 and brings down the nerves (phrenic) to supply the diaphragm
What four embryonic parts does the diagram form from?
septum transversum
2 pleuraperitonial membranes
peripheral body wall muscle
mesentery of oesophagus
What part of the diaphragm does the septum transverse form
Central tendon
What two parts form the muscular part of the diaphragm
2 pleuraperitonial membranes
(extended visceral + pleural membranes)
peripheral body wall muscle
What part of the diaphragm does the mesentery of oesophagus form
the crura of the diaphragm
Define fitsula and aretesia
Fistula
an abnormal or surgically made passage between a hollow or tubular organ and the body surface, or between two hollow or tubular organs
Artesia
a condition in which an orifice or passage in
the body is (usually abnormally) closed or absent
What occurs in the congenital condition Tracheoesophageal fistula
Trachea, larynx and oesophagus fail to separate, oesophagus blocked of and fails to develop
What are the congenital developmental abnormalities occurring in respiratory embryology
Tracheoesophageal fistula Tracheal stenosis cystadenomatoid malformation cyst formation Accessory lobes Surfacant and respiratory distress syndrome Agenesis Lobe of azygous vein Diaphragmatic hernia Histal hernia
Define congenital abnormality
birth defect, or anomaly, is a condition existing at or before birth regardless of cause
In the embryonic period, the lungs from as what first in the ventral part of the respiratory tract
Lung bud grown and develops until forms median trachea with two lateral pockets
Where do the pulmonary arteries individuate from in the embryonic period
6th aortic arch
What 3 differentiation stages of the lung buds are in the foetal period
pseuglandular stage
canalicular stage
saccular stage
When and what occurs in the pseuglandular stage
(7 -17 weeks). Setup of all pulmonary structures except elements needed for gas exchange
Lobes elongate, cells grow large and look like canals
In the canalicular stage what does the respiratory bronchiole give rise to?
the tubes that make up the respiratory part of the lung enabling gas exchange to take place
What is the development of the epithelium in the canalicular stage
Differentiation of epithelium into cuboidal secretory cells (Type II pneumocytes) which will synthesize the surfactant, and flat cells (Type I pneumocytes).
How long does the canalicular stage take
17-27 weeks
What is finally formed in the saccular stage of lung bud development and what is the cell change
how long does this take
Formation of alveolar sacs which change in epithelium to simple squamous
week 27-40
What separates the alveolar sacs
separated by primary septa
What progressively divides the alveolar into smaller sub units forming alveoli
secondary septa
What stage of differentiation is in the postnatal period and how long is the process
Alveolar stage (32 weeks to 8 years)
What occurs in the alveolar stage
formation of alveoli alveoli enlarge (increase as lungs increase)
What produces surfactant, whats it composed of and its function
type 2 pneumocytes
phospholipids and proteins
Counteracts surface tension at air-alveolar interface
What is a major cause of respiratory distress syndrome and what does this go on to from and prevent
surfactant deficiency
Hyaline membrane preventing the function of gas exchange
What is an example of a congenital condition that is asymptomatic and causes no harm
An accessory lobe
What is the congenital condition of Agenesis of the lung
complete absence of bronchus, parenchyma, and vessels - lung don’t develop
What is the congenital condition of Lobe of Azygos vein
Lung grows on either side of azygous vein and invaginate it
What embryonic component forms the primitive part of the diaphragm
pleuroperitoneal membrane
What is the three major defects causing diaphragmatc hernia
Failure of the diaphragm to completely close during development
Herniation of the abdominal contents into the chest
Pulmonary hypoplasia
Define the term hernia
general term used to describe a bulge or protrusion of an organ through the structure or muscle that usually contains it
What are the two different hernias
diaphragmatic hernia
hiatal hernia
Define Pulmonary hypoplasia
incomplete development of the lungs, resulting in an abnormally low number or size of bronchopulmonary segments or alveoli
What occurs in a diaphragmatic herniae
Protrusion occurring through the diaphragm muscle
Where does a hiatal hernia protrude the diagram
the protrusion of an organ, typically the stomach, through the oesophageal opening in the diaphragm
What are the two forms of hiatal hernias
sliding hiatus hernia - into the oesophagus
paraesophageal hiatus hernia - beside the oesophagus
When is diaphragmatic closure
18 weeks
