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Epithelium of the trachea, larynx, branchi, and lungs is made of what embryonic tissue
Endodermal
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The cartilaginous, muscular, and connective tissue components of the trachea and lungs are derived from what embryological tissue
Splanchnic mesoderm surrounding the foregut
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When does the lung bud begin forming and from where
Week 4, As an outgrowth from the ventral wall of the foregut
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The lung bud is also known as
- Respiratory bud
- Laryngealtracheal diverticulum
- Respiratory divertuculum
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The foregut where the trachea buds eventually ends up forming
Esophagus
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What divides the trachea from the esophagus
Tracheoesophageal septum
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What is a fistula
An abnormal developmental connection
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Atresia
Absence of an opening
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Tracheoesophageal fistulas are often associated with
Esophageal atresia
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What is the most prevelant type of tracheoesophageal fistula
Atresia of the esophagus on the cranial end, and a fitsula formed with the trachea and esophagus that the caudal end (90% of the time)
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What are the clinical features of a baby born with tracheoesophageal fistulas
- Episodes of gagging and cyanosis after feeding
- Reflux of gastric contents into lungs
- Accumulation of mucous or saliva in mouth
- Pneumonia or Pneumonitis
- Polyhydramnios
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Polyhydramnios
Excess fluid in amniotic sac
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VACTERL association
- A group of genital abnormalities that are often expressed together
- Vertebral
- Anal Atrasia
- Cardiac effects
- Tracheo-Esophageal fistulas
- Esophageal Atresia
- Renal abnormalities
- Limb defects
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1/3 of the TEF's have what as well
Cardiac defects
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The respiratory primordium maintains its communication with the pharnx through the
Laryngeal orifice
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The development of the larynx epithelium originates from
Endoderm and cartilages (thyroid, cricoid, arytenoid) from the 4th and 6th pharyngeal arches
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When do the main bronchi and secondary bronchi begin to develop, and from where
During the 5th week forming from the lung buds forming 3 secondary bronchi on the right and 2 on the left
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What happens in lung development during the 6th week
Tertiary branching of the bronchi forming 10 on the right and 8 on the left
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Each tertiary bronchus with surrounding mesenchyme is the primordium of
A bronchopulmonary segment
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By 24 weeks of development, how many orders of branches of bronchus are present
17, the last 6 develop after birth
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What are the signals that trigger bronchi branching, and where do they come from
Fibroblast growth factor (FGF), from the splanchnic mesoderm surrounding them
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As lung buds grow, what do they invade
Pericardioperitoneal canals
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What mesoderm covers the outside of the lung and forms visceral pleura
Splanchinic
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What mesoderm covers the body wall and ends up forming the parietal pleura
Somatic mesoderm
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Congenital diaphramatic hernia
Intestines herniate in to the thorax compressing lung, more common on the left then the right
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What are the four developmental periods of the development of the lungs
- Pseudoglandular (5-16 wks)
- Canalicular (16-26 wks)
- Terminal sac (26wks-birth)
- Alveolar (8 months to childhood)
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What happens in the pseudoglandular period (5-16 weeks)
- Developing lung resembles branching pattern of a compound exocrine gland
- Respiratory tree has developed terminal bronchioles
- No Alveolar present
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What happens in the canalicular period of development of the lungs (Wks 16-26)
- Terminal bronchioles give rise to 2 more respiratory bronchioles giving rise to 3-6 alveolar ducts
- Lined by simple cuboidal epithelium surrounded by mesoderm with a prominent capillary network
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In the Terminal sac period of develop, what happens (week 26-birth)
- More primitive alveoli develop
- Cuboidal epithelium change into thin flat cells with numerous capillaries and lymph
- Epithelium differentiates into Type I and II pneumocytes
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What is a terminal sac
Primitive alveoli
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When does the production of surfactant begin
Week 20
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What happens in the alveolar period (birth -8 years)
- Mature alveoli with developed capillary contact
- Increase in the # of respiratory bronchioles
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Most alveoli don't develop until
After birth, 90%
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Why is fetal breathing important
- It is essential for normal lung development through exercise of breathing movements
- Also crucial for pneumocyte development
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What are the three routes that the baby clears the lungs of amniotic fluid post birth
- Through the nose and mouth
- Pulmonary capillaries
- Lymphatics and pulmonary arteries
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What is a common cause of premature fetal death relating to the respiratory system
Respiratory distress syndrome
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Pulmonary hypoplasia is found often in association with
Bilateral renal agenesis
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What causes congenital cysts of the lung
Abnormal dilation of the bronchi
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Which bronchi is larger
The right, more prone to objects getting lodge in it
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