Embryology Flashcards
upper respiratory tract composed of
- nose
- oral cavity
- pharynx
- upper larynx
lower respiratory tract composed of
- lower larynx
- trachea
- bronchi
- bronchioles
- alveoli
goal of respiratory tract
- conduct air
- gas exchange with the blood
further breakdown of lower respiratory tract
- primary bronchus
- secondary bronchus
- tertiary bronchus
- terminal bronchiole
gases are exchanged between
- blood in capillaries
- air in alveoli
gas exchange requires that alveoli have
- alveoli have thin walls
what type of epithelium is found in the lower respiratory tract
why is this important
- simple squamous
- thin so it allows for gas exchange
alveolar lumens are lined by
- surfactant
surfactant is secreted by
- type 2 pneumocytes
role of surfactant
- keeps alveolar surface tension low so that thin-walled alveoli don’t collapse
what are collapsed alveoli called
- atelectasis
what can atelectasis cause
- respiratory distress
trachea and lung develops from which germ layer
- endoderm
the lower respiratory tract arises as an _______ of the _____
- anterior diverticulum
- of the GI tract (specifically the pharynx)
what is a diverticulum?
- a blind tube arising from a cavity or tube
when does the trachea and lung form?
- during week 4
why does the anterior diverticulum make sense?
- because it forms anterior to the esophagus
in what direction does the lower respiratory tract develop?
- cranial to caudal
what are the most caudal structures?
- alveoli
what are the last structures to form?
- alveoli
is there any respiratory function (gas exchange) in-utero?
where does it occur?
- no
- occurs in the placenta
importance of fetus respiratory movements
- bring amniotic fluid in and out of developing respiratory tree
- necessary for lung development
placenta formed by
- the embryo
what does the maternal blood release into the placenta?
where does it go?
- nutrients and O2
- goes into the fetal blood
what does the fetal blood release into the placenta?
where does it go?
- releases CO2 and wastes
- goes into the maternal blood
placenta functions as
- fetal lungs, kidney, and GI tract
what does the fetus “breathe”
- amniotic fluid (not air)
post-natal breathing requires
when must this be accomplished?
- alveoli are formed
- alveoli have thin walls
- alveoli secrete surfactant to keep them open
- this must be accomplished by birth
a term fetus is how many weeks?
- 38 weeks
a term fetus normally has adequate amounts of ________ alveoli
- mature, thin-walled
a term fetus normally has adequate amounts of ______ for breathing air
- surfactant
what happens at week 22?
- primitive, thick walled alveoli begin to develop
when do the last alveoli develop
- around 7 years old
when is surfactant produced?
- around week 24
over time the thick alveolar walls become ____
- thin
over time increasing numbers of ______ develop
- air sacs
over time _________ production increases
- surfactant
in a premature infant, viability is partially dependent on the ability to
which requires
- breath air
- requires adequate quantities of surfactant
what happens if surfactant is deficient
- infant respiratory destress syndrome may develop
what can be used in premature infants while lungs continue to develop after birth?
- artificial surfactant
how many weeks before the baby is due defines prematurity
- at least 3
tracheoesophageal fistula arises in what weeks?
- 4-7
tracheoesophageal fistula most common type
- type C
tracheoesophageal fistula clinical symptoms in utero
- polyhydramnios - excessive amniotic fluid
tracheoesophageal fistula clinical symptoms after birth
- choking
- coughing
- cyanosis
- vomiting
embryonic lung development period in which weeks
what occurs
- 3-8
- bronchi and bronchioles form
pseudoglandular lung development period in which weeks
what occurs
- 5-16
- bronchioles branch into terminal bronchioles
canicular lung development period in which weeks
what occurs
- 16-26
- terminal bronchioles branch into respiratory bronchioles
saccular lung development period in which weeks
what occurs
- 26-38 (birth)
- alveolar ducts form
alveolar lung development period in which weeks
what occurs
- 36-38 and even further after birth
- alveolar sacs form
