E: Respiratory Flashcards
The respiratory diverticulum appears during week __
4
The respiratory diverticulum appears as an outgrowth of ___
foregut
The respiratory diverticulum is ___ derived
endoderm
Because respiratory diverticulum is endoderm derived, what adult structures are endoderm derived?
inner lining of larynx, trachea, bronchi, lungs
The lung bud grows out into the ____
splanchnic mesoderm
Because lung bud grows into splanchnic mesoderm, what adult structures are splanchnic mesoderm derived?
cartilageinous, musculature, connective tissue of trachae and lungs
The lung bud initially has an open communication with ___
foregut
Which direction does the lung bud grow?
caudal
As the lung bud grows caudally, what forms?
tracheoesophageal ridges
Tracheoesophageal ridges separate ____
the lung bud from the foregut
When tracheoesophageal ridges fuse, it becomes ___
tracheoesophageal septum
Tracheoesophageal septum:
dorsal part = ____
ventral part = ___
dorsal part = esophagus
ventral part = laryngotracheal tube (lung bud + trachae)
What is the laryngotrachael tube?
early in development when lung bud and trachea are still together
Tracheoesophageal septum can lead to what 2 main developmental disorders?
- esophageal atresia
2. tracheoesophageal fistula
What is esophageal atresia?
complete septation of the esophagus
blind end sac
food has nowhere to go
What is a tracheoesophageal fistula?
connection between tracheo and esophagus
so food and air are going t o the wrong places
If you have esophageal atresia, do you automatically have tracheoesophageal fistulas?
no
you can have esophageal atresia with or without tracheoesophageal fistulas
The lung bud maintains communication with pharynx through ___
laryngeal orifice
The lung bud maintains communication with ___ through the laryngeal orifice
pharynx
Describe the shape of the laryngeal orifice
initially is a SAGITTAL SLIT
changes into a T SHAPED opening
Larynx cartilage and musculature is derived from pharyngeal arches ___
4 and 6
Mesenchyme of pharyngeal arches 4 and 6 become _____ in the larynx
thyroid cartilage
cricoid cartilage
arytenoid cartilage
The epiglottis is formed from mesenchyme of the ____
caudal hypopharyngeal eminence
hypopharyngeal eminence
- where is it
- what does it become
@ base of tongue
mesenchyme = becomes EPIGLOTTIS
Laryngeal mm from pharyngeal arch 4 is innervated by ____
Laryngeal mm from pharyngeal arch 6 is innervated by ____
4 = superior laryngeal n
6 = recurrent laryngeal n
At day __ lung bud divides into 2 primary bronchial buds
28
At day 28 the lung bud divides into ___
2 primary bronchial buds
At week __, the R/L primary bronchial buds divide
5
At week 5, the R/L primary bronchial buds divide into ___
right = 3 secondary bronchial buds
left = 2 secondary bronchial buds
At week __, the R/L secondary bronchial buds divide
5-6
Week 5-6, the R/L secondary bronchial buds divide into ___
right = 10 tertiary bronchial buds
left = 8 tertiary bronchial buds
Once it starts to divide, the lung bud is growing in which direction?
caudal and LATERAL
The lung bud is growing laterally into ___
pericardioperitoneal canal
How does the shape of the pericardioperitoneal canal change?
What does this become?
It narrows
Becomes thep leural cavities
Splanchnic mesoderm becomes ___
Somatic mesoderm becomes ___
splanchnic – visceral
somatic – parietal
The respiratory tree produces small branches called ___
terminal bronchioles
At week ___ the terminal bronchioles divide
16-28
At weeks 16-28, the terminal bronchioles divide into ____
2 or more respiratory bronchioles
What is so significant about the change from terminal bronchioles to respiratory bronchioles?
this is the transition period from CONDUCTING to RESPIRATORY
By week ___ terminal sacs (primitive alveoli) are formed
36
What are the 4 stages of branching?
- psuedoglandular period
- canalicular period
- terminal sac period
- alveolar period
Which of the stages of branching are fetal vs. neonatal?
fetal = psuedoglandular, canalicular, terminal sac
late fetal/neonatal = alveolar
Which of the stages of branching would a fetus survive?
fatal = psuedoglandular and canalicular
could survive w/ assistance = termianl sac period
survive = alveolar
Psuedogladnular period
- when?
- what is present?
5-16 weeks
branching continues to form TERMINAL BRONCHIOLES
Canalicular period
- when?
- what is present?
16-26 weeks
each terminal bronchiole divided into 2+ respiratory bronchioles which divides into 3-6 alveolar ducts
Terminal sac period
- when?
- what is present?
26 weeks
terminal sacs (primitive alveoli) are formed
capillaries establish close contact
Alveolar Period
- when?
- what is present?
8months - early childhood
mature alveoli have well developed epithelial-endothelial contact
Describe the epithelium at 26 weeks of the terminal sacs in respiratory system?
mostly simple squamous cells = type 1 alveolar cells
a few type 2 alveolar cells (surfactant)
Describe type 1 alveolar cells
simple squamous cells that line terminal sacs
makes up most of epithelium
Describe type 2 alveolar cells
scattered among type 1 alveolar cells
these produce, store, secrete pulmonary surfactant
Where is surfactant present?
forms film over internal walls of alveolar sacs
What is the function of surfactant?
counteracts surface tension
facilitates expansion of terminal sacs by preventing lung collapse
What is atelectasis?
lung collapse
Production of surfactant occurs at weeks ___
20-22