Unit III: Respiratory System Flashcards
The ___ mesoderm will form the cartilages and smooth muscle of the larynx, trachea, and bronchi
Splanchnic
Divisions of the laryngotracheal diverticulum
- ventral part
2. dorsal part
What makes up the ventral part of the laryngotracheal diverticulum?
Larynx, trachea, bronchi, lungs
What makes up the dorsal part of the laryngotracheal diverticulum?
Esophagus
All laryngeal cartilages except for the ___ develops from the 4th-6th pharyngeal arches
Epiglottic cartilage
The cricothyroid muscle develops from the ___ pharyngeal arch
Fourth
All muscles of the larynx except the cricothyroid are supplied by the ___
Recurrent laryngeal nerve
The cricothyroid muscle is supplied by the ___
Vagus nerve
At what ages in a human is the larynx in a high position?
0-1
___ mesoderm forms the C-rings and the smooth muscle of the trachea
Splanchnic
What is splanchnic mesoderm?
Visceral-> relating to internal organs
What is somatic mesoderm?
Related to the body wall
What is tracheoesophageal fistula?
- abnormal opening between the trachea and the esophagus
- from incomplete fusion of the tracheoesophageal folds
- esophageal atresia
- upper esophagus is a blind pouch
- infants cannot swallow
- requires surgery
The upper division of the bronchus becomes the ___
Superior lobar bronchus
The lower division of the bronchus becomes the ___
Middle and inferior lobar bronchi
How many segmental bronchi are in each lung?
10
As the lung develops, the splanchnic mesoderm on its ___ surface forms the visceral pleura
Outer
The somatic mesoderm covering the inside of the ___ forms the parietal pleura
Thoracic wall
What is the space called between the parietal and visceral pleura?
Pleural cavity
4 stages of lung development
- pseudo glandular
- cancalicular
- terminal sac
- alveolar
When is the pseudoglandular stage?
6-16 weeks
When is the canalicular stage?
16-26 weeks
When is the terminal sac stage?
26 weeks-birth
When is the alveolar stage?
32 weeks-8 years
Can a premature infant survive at the pseudoglandular stage?
No
Can a premature infant survive at the canalicular stage?
Possibly- some gas exchange can occur, but the infant requires intensive care and mortality rate is high
Can a premature infant survive at the terminal sac stage?
Possibly- intensive care is needed due to insufficient lung surfactant
What are type 1 pneumocytes?
Squamous epithelial cells in the walls of the terminal sacs
What is the function of type 2 pneumocytes?
Secretes surfactant
What is the purpose of surfactant?
Reduces tension between the air and alveolar surfaces-> allows expansion during expiration
When does adequate levels of surfactant reach?
26-28 weeks
What is the pseudoglandular stage characterized by?
Branching of bronchioles and formation of bronchopulmonary segments
What is the canalicular stage characterized by?
- expansion in diameter of bronchi
- vascularization of the lung
- formation of respiratory bronchioles and alveolar ducts
What is the terminal sac stage characterized by?
Formation of numerous terminal sacs-> primordial of the alveoli
What is the alveolar stage characterized by?
Development of mature alveoli
What 3 factors determine if a premature infant will be able to exchange gases successfully?
- adequate surfactant
- formation of functional alveoli
- establishment of pulmonary/systemic circulation
Fetal breathing movements function to:
- exercises the muscles of respiration
2. stimulate lung development
T/F: the lungs are completely filled with amniotic fluid at birth
False- half filled-> must be removed to allow inflation of the lungs
How do you clear the amniotic fluid from the lungs?
- expulsion through the mouth and nose during birth
- via pulmonary blood vessels
- via pulmonary lymphatics
T/F: pulmonary lymphatic vessels are larger and more numerous in the fetus than in the adult
True
3 factors that are essential for normal lung development
- adequate thoracic volume
- adequate amniotic fluid
- fetal breathing movements
What is oligohydramnios and pulmonary hypoplasia?
- insufficient amniotic fluid is present
- restricts lung expansion
- underdevelopment of the lungs
What is respiratory distress syndrome?
- rapid, labored breathing after birth
- affects 2% of neonates
- caused from surfactant deficiency
