Respiratory dev Flashcards
Where does the laryngotracheal groove develop from?
Ventral wall of primitive pharynx
- caudal to the 4th pair of pharyngeal pouches
What primitive tissue do the gland of larynx develop from? What other structures develop from the same type of tissue?
Endoderm
Trachea, bronchi and pulmonary epithelium
Why are the epithelium and glands of respiratory tract derived from the endoderm?
Because it is an outgrowth of the developing GI tract
What then are the surround tissues derived from?
Splanchnic mesenchyme
What are the surrounding tissues?
CT
Cartilage
Smooth muscle
What do the primary bronchial buds develop from?
the laryngotracheal
diverticulum
What separates the developing respiratory tract from the developing foregut?
Tracheoesophageal folds to create the laryngotracheal tube
where does the laryngeal cartilage derive from?
4th and 6th pharyngeal arches
Where do the 4th and 6th pharyngeal arches derive from?
mesenchyme from the neurocrest cells
Where do the larngeal muscles come from?
4th and 6th pharyngeal arch myoblasts
What innervates the laryngeal muscles?
Vegas
- Recurrent laryngeal
- superior laryngeal
- inferior
What another name for pharyngeal arches?
Branchial
Which nerves supplies the muscles and which supplies the sensory to the laryngeal muscles?
Muscles by recurrent and inferior laryngeal
Superior laryngeal supplies sensory
What is responsible for the dev of the trachea?
tracheoesophageal folds
-
What is the most common anomaly of the lower respiratory tract?
Tracheoesophageal fistula
- an abnormal comm because trachea and esophagus
What is commonly ass with tracheoesophageal fistulas?
esophageal atresia
-85% of the time
What are some common complications with tracheoesophageal fistulas?
- food or gastric contents may enter lungs–> aspiration
- polyhydramnios
what does the entire respiratory system dev from?
Respiratory diverticulum
Laryngotracheal groove–> larngotracheal diverticulum–> respiratory bud–> primary bonchial buds–> secondary bronchial buds–> segmental branches
Where do the bronchial buds dev from?
pericardioperitoneal canal which is a portion of the intra-embryonic coelom
What does splanchinic mesenchyme give rise to in the lung?
- visceral pleura
- cartilaginous plates
- SM
- CT
- pulmonary CT
What is the parietal pleura derived from?
Somatic mesoderm
also gives rise to the body wall
What is an azygous lobe?
-Part of the superior lobe of the right lung grows medial to azygous vein instead of lateral to it
What causes agenesis of the lung?
-Failure of lung bud to dev
What is lung hypoplasia commonly ass with?
-Congenital diaphragmatic hernia
What is another common cause of lung hypoplasia?
-Oligohydramnios
Do bronchioles have cartilages in their walls?
no
What is the progression of airway after the terminal bronchioles?
-Respiratory bronchioles–> Alveolar ducts –>alveolar sacs–> alveoli
What is the first stage of lung maturation? When?
- Pseudoglandular stage
- 6-16 weeks
During the pseudoglandular stage what devs? Can the baby survive if its doesn’t?
- Ductal elements like bronchi and terminal bronchioles
- No fetuses cannot survive because alveoli are not present
What is the second stage of lung dev called? When
- Canalicular stage
- 16-26 weeks
What devs during the canalicular stage? Can fetus survive?
- Respiratory passageways like respiratory bronchioles and alveolar ducts
- Vascularization too
- Yes respiration is possible
What is the 3rd stage of lung maturation? When?
- Terminal sac or saccular stage
- 26- birth
What is the 4th stage of lung maturation? When?
- Alveolar stage
- 32 weeks- 8 years old
What is another name for pneumocytes type 1?
- Type 1 alveolar cells
- Squamous epithelium of endodermal origin
What devs during the saccular stage?
- Type 1 alveolar cells
- Capillary and lymphatics
What secretes surfactant and in what stage?
- Type II alveolar cells or pneumocytes
- Made up of phospholipids and two proteins
What is the purpose of surfactant?
-Serves to lower surface tension at the air-alveolar interface
What is infant survival dependent upon?
- Surfactant
- Vasculature
What devs during the alveolar stage of lung maturation?
- Maturation of alveoli
- Increase respiratory bronchioles and primitive alveoli
What fuses between type 1 alveolar cells and the endothilum of capillaries?
- Both basement membranes fuse
- No CT between
How many alveolar are we born with? At age 8?
- 150 mil
- 300 mil
What are fetal breathing movements?
- Occur prior to birth
- Stimulate lung dev and facilitates dev of respiratory musculature
Where does the fluid at birth in the lungs come from?
- ½ from amniotic fluid
- ½ from lung tissue itself
Where does this fluid go after aeration?
- Through mouth after pressure from vaginal delivery
- Pulmonary arts/veins/capillaries
- Lymphatics
What is respiratory distress syndrome?
- Hyaline membrane dz
- 20% of infant deaths
- deficiency in surfactant
- protein/fibrin rich exudation of alveolar wall
What can one give to accelerate lung dev?
- Glucocorticoids
What is diff from newborn lungs from still born lungs?
- Newborn have air and float
- Stillborn are firm and sink
