Respiratory System (Severson) - W1

Question 1

Where and from what does the laryngotracheal groove develop from?

Answer 1

ventral wall of the primitive pharynx, caudal to the 4th pair of phayrngeal arches.

Question 2

What is derived from endoderm?

Answer 2

• epithelium of lARYNX, TRACHEA AND BRONCHI
• glands
• pulmonary epitheilum

Question 3

What is derived from splanchnic mesenchyme?

Answer 3

• connective tissue
• cartilage
• smooth muscle

Question 4

What does laryngeal cartilage develop from?

Answer 4

Neural crest mesenchyme

Question 5

What does the laryngotracehal tube form from?

Answer 5

cranial part of foregut - tracheoesophageal folds and septum divide it.

Question 6

Where is the epitheial lining of the larynx derived from?

Answer 6

endoderm

Question 7

What are laryngeal cartilages derived from?

Answer 7

4th and 6th pharyngeal arches (mesenchyme derived from neural crest cells)

Question 8

What do laryngeal muscles develop from and what are they innervated by?

Answer 8

develop from myoblasts of 4th and 6th pair of pharyngeal arches.

Innervated by vagus nerve - superior laryngeal and recurrent laryngeal nerves

Question 9

How is the trachea formed?

Answer 9

Formed by separation of the foregut into the trachea and esophagus by growth of the tracheoesophageal fold & septum.

Question 10

in the trachea, where are epithelium and glandular elements derived from?

Answer 10

Endodermal origin

Question 11

In the trachea, where are cartilage, connective tissue, and muscle derived from?

Answer 11

splanchnic mesoderm

Question 12

Explian what a tracheosophageal fistula is and what it is associated with

Answer 12

abnormal communication between trachea and esophagus.

Associated w/esophageal atresia.

Question 13

What causes a tracheoesophageal fistula?

What are complications?

Answer 13

• caused by: abnormal partitioning of the laryngotracheal tube by the tracheoesophageal septum
• complications
  
  • pneumonia from food or gastric contents entering lungs
  • polyhydramnios due to amnitoic fluid accumulation - can’t pass to stomach for reabsoprtion.

Question 14

What does the primary bronchial bud grow into?

Answer 14

pericardioperitoneal canals

Question 15

in the bronchi and lungs, what is derived from the splanchnic mesoderm

Answer 15

• cartilaginous plates
• bronchial smooth muscle
• connective tissue
• pulmonary connective tissue
• pulmonary capillaries

Question 16

What is the Parietal pleura derived from?

Answer 16

Somatic mesoderm

Question 17

What is the visceral pleura derived from?

Answer 17

Splanchnic mesoderm

Question 18

How is an azygous lobe formed?

Answer 18

part of the superior lobe of the right lung grows MEDIAL to the azygous vein instead of lateral to it.

Question 19

What is lung hypoplasia usually associated with?

Answer 19

Congenital diaphgramatic hernia

Question 20

What is another cause besides congential hernia that can cause pulmonary hypoplasia

Answer 20

Oligohydramnios

Question 21

What can cause oligohydramnios?

Answer 21

• insuffiencent amount of fluid
• bilateral renal agenesis - urine is diminished reducing the amount of amniotic fluid

Question 22

What is seen with Potter’s syndrome?

Answer 22

pulmonary hypoplasia and bilateral renal agenesis

Question 23

T/F. Bronchioles have cartilage.

Answer 23

False, just the bronchi do.

Question 24

4 stages of lung development

Answer 24

1. Pseudoglandular stage - 6-16 weeks
   
   1. bronchi and terminal bronchioles form
   2. no alveoli
2. Canalicular stage - 16-26 weeks
   
   1. vascularization and respiration possible
   2. respiratory bronchioles and alveolar ducts develop
3. Terminal sac period 26 weeks to birth
   
   1. alveolar cells form - surfacant
   2. capillary and lymph vessels form
4. alveolar period - late fetal to 8 years
   
   1. ​maturation of alveoli
   2. thin respiratory membrane
   3. aveloli increase

Question 25

What are type I alveolar cells made up of?

Answer 25

squamous epithelium of endodermal origin

Question 26

What do **type II alveolar cells produce?**

Answer 26

**surfactant** (phospholipids and 2 proteins) leads to lower surface tension at air-alveolar interface

Question 27

What is featl breathing movements and when do they occur?

Answer 27

**FBMs** occur prior to birth and are essentail for normal lung development. Stimulate lung development and facilitates development of respiratory muscles.

Question 28

What are 3 ways removal of amniotic fluid occurs at birth?

Answer 28

* through mouth and nose by pressure on thorax during vaginal deliveries * into pulmonary arteries, veins and capillaries * into the lymphatics

Question 29

What is **respiratory distress syndrome?**

Answer 29

* deficiency of surfactant and injury to alveolar wall * leads to **protein rich fibrin-rich exudate** into alveolar space and formation of **hyaline membranes**

Question 30

what administered during pregnancy can accelerate fetal lung development

Answer 30

glucocorticodis (B-methasone)

Question 31

Why do stillborn infant's lungs sink in water?

Answer 31

they contain fluid, not air.

Question 32

When does pulmonary surfactant formation occur?

Answer 32

**20 weeks** but not sufficient until 26-28 week.

Question 33

What are congenital lung cysts?

Answer 33

* form by DILATION of terminal bronchioles due to distrubance in bronchial development during LATE fetal life * lungs have HONEYCOMB appearance