development of the respiratory system Flashcards
when does the respiratory system begin
Day 22 (forth week)
major changes in the respiratory system happens
5th and 6th month
how long does the respiratory system develop
past the first breath at birth up to age 3 (possible for 7-8 years)
what part of the respiratory system appears at week 4
Respiratory diveritulum
what is the respiratory diverticulum
the lung bud
how does the respiratory diverticulum grow as
As an outgrowth of the foregut
what parts of the respiratory system is endoderm
Inner lining of larynx
Trachea
Bronchi
Lungs
what parts of the respiratory system is splanchnic mesoderm
Cartilaginous
Muscular
Connective tissue component of trachea and lungs
what does the lung bud grow into
Splanchnic mesoderm
what is the lung bud open to
Open comm with the foregut
what causes the lung bud to separate from the foregut
as the bud grows caudally, tracheoesophageal ridges separate the bud from the foregut
tracheoesophageal ridges eventually fuse to make
The tracheoesophageanl septum
Abnormalities in partitioning of the esophagus and trachea by the tracheoesophageal septum result in
Esophageal atresia(blind end sack) with or without tracheoesophageal fistulas (TEF)- air goes into sack
foregut anomolies mean you may have
Respiratory anomolies
How does the respiratory diverticulum maintina comm with the parynx
Laryngeal origice
what is the shape of the laryngeal orifice orignally
Safittal slit
what does the Larygeal orifice change to in shape
T-shaped opening
surrounding tissues of the Laryngeal orifice
Epiglottal swelling Arytenoid swelling (inferior) originally laryngeal swellings
what do the laryngeal cartilage and muscles arise from
Pharyngeal arch 4 and 6
what innervate the muscles of the larynx
Vagus nerve
what does the mesenchym of the 4th and 6th arch turn into
Thyroid cartilage
Cricoid Cartilage
Arytenoid cartilce
what does the epiglottis form from
Mesnechyme of the caudal hypopharyngeal eminence
LAryngeal mm arising fromt the first arch are innervated by
super laryngeal n
Innervation of laryngeal mm fo the 6th arch
recurrent laryngeal n
when does the lung bud devide into the primary bronchial buds
day 28
when does the primary bronchial buds devide into secondary bronchial buds
30 days(week 5)
when does the secondary bronchial buds devide into teritary bronchial buds
38 days ( 5th and 6th)
as the lung buds devide and grow what is carried with them
Pleural mesenchyme
how many seconadry bronchial buds are there
Left: 2
Right: 3
number of tertiary bronchial buds
R: 10
L: 8
where does the lung buds grow into
Pericardioperitoneal canals
What forms the pleural cavities
Lung bud growth into the pericardioperitoneal canals
what gives rise to the visceral pleura of the lungs
Splanchnic mesoderm
what gives rise to the parietal pleura
Somatic mesoderm
what fills the pleural caviy in the development
Serous fluid still
what does the respiratory tree create
Small branches called terminal bronchioles
when do terminal rbonchiole devide
weeks 16-28
what do terminal bronchiole divide into
respiratory bronchia
when are the terminal sacs (primitive alveoli)
week 36
separates the conditioning/conducting portion of lungs
ends at terminal bronchioles
Gas exchange at respiratory bronchioles
as the terminal sacs form what else is just beginning to form
Blood islands for the capillaries in the mesenchyme
stages of lung maturation
Pseudoglandular period- branches for terminal bronchioles
Canalicular period- respiratory brnahces begin to turn into alveolar ducts
TErminal sac- terminal sacs form, and capillaries begin
Alveolar period; mature alveoli with capillary contacts
Time of the pseudoglandular period
5-16weeks
Canalicular period
16-26 weeks
time of terminal sac period
26 week to birth
alveolar period
8 months till childhood
fetal stages of lungs
Pseudoglandular, canalicular, terminal sac
What stages are late fetal and enonatal
Alveolar period
what happens in the pseudoglandular period
Branches has continued to form terminal bronchioles
No respiratory or bronchioles or alveoli present
Capillaries presnet but not asssociated
what happens in the canicular period
Each terminal bronchiole divides into 2+ respiratory bronchioles
These devide into 3-6 alveolar ducts
air blood relation is not there yet
beginning of cellular specialization
what happens in terminal sac period
Terminal sacs form and capillaries become close to sacs
Functional development
fetus can possibly surive if born here
no surfactant cells
what do terminal sacs look like a 26 weeks
single layer of simple squamous cells
cells through which gases diffuse
Type I alveolar cells and associate with capillaries
what are the shape of type II alveolar cells
Rounded
Shape of Type I alveolar cells
flat
Roll of type II alveolar cells
Produce, store, and secrete pulmonary surfactant
what does Surfactant form
Film over the internal walls te alveolar sacs and counteracts surface tension
Roll of surfactants
Facilitate expansion of terminal sac and prevent collapse (atelectasis)
when does surfactant begin to be produced
20-22 weeks
what fills the respiratory tree before brith
Amniotic fluid
what happens at first breath to liquid in lungs
All the fluid goes out it and secreted surfactant forms on top of remaining fluid
what happens to prevent colaspse of alveolus
Surfactant prevents alveolar collapse
what happens at the alveolar period
Mature alveoli have well developed epithelial endothelial contacts
Type I and II alveolar
Smooth msucles are present
