Overview of the Pulmonary System/Lung Development Flashcards
Lungs are the only organ in mammals that can participate in ___________.
gas exchange
The lungs are the only organ that constantly surveys _____________.
the inside of the body (100% of cardiac output) and the outside of the body
The airway branches about 23 times. Gas exchange does not occur in the first _______ branch points.
16
There are two types of pneumocytes: ____________.
type I (simple squamous epithelium) and type II (secretory)
Differentiate ventilation and respiration.
Ventilation is the movement of air into and out of the lungs, while respiration is gas exchange.
The lungs develop from the embryonic ________.
endoderm
The lung buds develop ventrally into the mesoderm at week ________.
four
The lung buds develop from buds between the _____________.
4th and 6th branchial (aka pharyngeal) arches
At week _______, lung development is halted by impeding on the liver.
seven
When does the embryonic stage take place?
4-7 weeks
When does the pseudoglandular stage take place?
7-16 weeks
When does the canalicular stage take place?
17-26 weeks
What epithelium differentiates in the pseudoglandular stage?
Conducting airway epithelium
_____ percent of true alveoli don’t appear until after birth.
Ninety
The lungs bud off of the __________.
primitive foregut
Type II pneumocytes appear at the end of ___________.
month six
What is the postnatal stage called?
Alveolar stage
When does the first bronchial branching occur?
Around day 28
The branching pattern is determined by __________.
the mesoderm
Branching occurs by ____________.
collagen deposition in the forking of the branch
The canalicular stage is characterized by formation of the __________.
bronchioles and capillary bed
The saccular stage takes place from __________.
26 weeks to birth
What happens in lung development after birth?
The capillary network lengthens.
Respiratory bronchioles subdivide to produce terminal sacs in the _________.
saccular stage
The bronchus is lined with _________ epithelium, while the bronchioles are lined with ___________ epithelium.
ciliated pseudostratified columnar; simple
Gas exchange takes place distal to the ___________.
terminal bronchioles
In addition to secreting surfactant, type II cells also __________.
repair type I cells
