Embryology Flashcards
Which layer of the embryo does the lung bud originate from?
Endoderm
Where does the lung bud come from?
The anterior upper part of the gut tube
What grows together to separate the oesophagus from the trachea?
The tracheoesophageal ridge
How are all respiratory congenital defects corrected?
Surgery
What is the most common respiratory congenital defect?
A blind ending oesophagus from the mouth and a communication between the trachea and the oesophagus with the part coming from the stomach
What is a blind ending of the oesophagus called?
Oesophageal atresia
What is a communication between the trachea and the oesophagus called?
Tracheoesophageal fistula
At what stage do the left and right primary bronchial buds form?
4 weeks
At what stage do the secondary bronchial buds form?
30 days
How many secondary bronchial buds form on the right and how many form on the left?
Right = 3 Left = 2
At what stage do the tertiary bronchial buds form?
38 days
What forms the visceral pleura and the tissue and cartilage surrounding the lung?
Visceral mesoderm
What occurs in the embryonic stage of maturation of the lungs and what is the time period?
Time period = 26 days- 6 weeks
Respiratory diverticulum and branching to give lungs, lobes and segments
What occurs in the pseudoglandular stage of maturation of the lungs and what is the time period?
Time period = 6-16 weeks
14 more generation of branching to form tertiary bronchioles
What occurs in the canalicular stage of maturation of the lungs and what is the time period?
Time period = 16-28 weeks
Branching from the terminal bronchioles to at least 2 respiratory bronchioles
What occurs in the saccular stage of maturation of the lungs and what is the time period?
Time period = 28-36 weeks
Terminal sacs form and the capillaries make close contact
What occurs in the alveolar stage of maturation of the lungs and what is the time period?
Time period = 36 weeks into infancy
Alvioli mature
What type of cells produce surfactant?
Type 2 pneumocytes (cuboidal)
What is the role of sufactant?
Reduces alviolar surface tension preventing alveolar collapse.
Why do premature babies experience Acute Respiratory Distress Syndrome (ARDS)?
Type 2 pneumocytes are some of the last cells to develop therefore premature babies often do not produce enough surfactant and their alvioli are prone to collapse making it difficult for them to expand their lungs fully.
