Embryology (respi)

Question 1

Stages of respi development (earliest to latest)

Answer 1

Embryonic

Pseudoglandular

Canalicular

Saccular

Alveolar

Question 2

What is a lung bud/respiratory diverticulum?

Answer 2

Outpouching of developing foregut region

Question 3

What is necessary for functional stability?

Answer 3

Separation btw developing foregut and respiratory diverticulum

Question 4

Main origins for development of respi structures

Answer 4

Gut tube

Question 5

Fn of tracheoesophageal septum?

Answer 5

Separates trachea and esophagus

Question 6

What envelopes tracheoesophageal septum?

Answer 6

Mesoderm

Question 7

What facilitates separation of trachea and esophagus during fetal development?

Answer 7

Emergence of tracheoesophageal folds

Question 8

How is tracheoesophageal septum formed?

Answer 8

Fusing of tracheoesophageal folds in midline

Question 9

What complication arises if separation doesn’t occur completely?

Answer 9

Fistula

Question 10

How is bronchial bud formed?

Answer 10

Respiratory diverticulum bifurcates into right and left bud

Question 11

What does the bronchial bud turn into later on during development?

Answer 11

Pri bronchi

Question 12

When does formation of tertiary bronchi occur?

Answer 12

End of embryonic stage

Question 13

What happens during the pseudoglandular stage?

Answer 13

Formation of more intricate structures of the respi sys

Question 14

What is the canalicular stage?

Answer 14

Specialised development of respi component within lung themselves

Question 15

What happens during canalicular stage?

Answer 15

Terminal bronchioles -> respiratory bronchioles -> alveolar ducts -> alveolar sacs

Formation of canals and widening of canals

Increased vascularisation and respi bronchioles -> influx of pulmonary capillaries

Question 16

What is an acinus?

Answer 16

Unit consisting of terminal bronchioles, alveolar duct, terminal sac

Immature precursor to the final alveoli

Question 17

Is a foetus able to survive it is born premature during the canalicular stage?

Answer 17

Yes, some alveoli capable of supporting gas exchange

Question 18

What happens during the saccular stage?

Answer 18

Alveolar ducts -> alveolar sacs

Question 19

Type 1 vs type 2 alveolar cells

Answer 19

Type 1
- flat and thin
- needed for gas exchange

Type 2
- produce surfactant -> reduce surface tension of fluid in lungs to prevent collapse of alveoli

Question 20

What happens during the alveolar stage?

Answer 20

Proliferation and maturation of alveoli

Continuous increase in vascularisation -> increase in pulmonary capillaries surrounding each alveoli

Question 21

Describe blood circulation during fetal life

Answer 21

Lungs filled w/ fluid -> alveoli collapsed

Pulmonary vascular resistance high

Heart has shunts to bypass lungs because fetus is receiving oxygenation from placenta

Question 22

How does babies’ circulation change at birth?

Answer 22

Baby take breath -> lungs fill w/ air and pulmonary vascular resistance drops
- cardiac shunts close -> blood flows through lungs

Question 23

Components of developing diaphragm

Answer 23

Somites (muscles for diaphragm), septum transversum and pleuroperitoneal folds

Question 24

What happens if diaphragm is not fully formed?

Answer 24

Abdominal content herniate into thoracic cavity (congenital diaphragmatic hernia)

Question 25

What is a fistula?

Answer 25

Abnormal connection btw 2 hollow spaces

Question 26

What is esophageal atresia?

Answer 26

Narrowing/closure of adjacent esophagus

Question 27

Manifestations of tracheoesophageal fistula

Answer 27

Failure to thrive Aspiration/lung infection Polyhydramnios - fetus can't swallow amniotic fluid -> excess amniotic fluid in womb

Question 28

Signs that a baby has tracheoesophageal fistula

Answer 28

GIT distended w/ air -> air go into esophagus instead of trachea Feeding tube doesn't extend to stomach as it's caught in proximal oesophagus

Question 29

How to treat tracheoesophageal fistula?

Answer 29

Surgical repair

Question 30

What does newborn respiratory distress syndrome/hyaline membrane disease occur?

Answer 30

Occurs due to insufficient surfactant production in immature lung of premature infants

Question 31

Clinical features of newborn respiratory distress syndrome

Answer 31

Breathing in rapid and laboured manner Indrawing of infant's ribcage -> use of accessory respiratory muscles to generate high intrathoracic pressure to expand poorly compliant lung Cyanosis -> blue and purple discolouration of skin

Question 32

Features of an X-ray of an infant w/ respiratory distress syndrome

Answer 32

Decreased lung vol Increased patchiness of lung

Question 33

Management of newborn respiratory distress syndrome

Answer 33

Surfactant therapy Antenatal corticosteroids -> accelerate fetal lung development and surfactant production Continuous positive airway pressure (CPAP)

Question 34

What is congenital diaphragmatic hernia?

Answer 34

Failure of normal closure of the pleuroperitoneal membrane

Question 35

Clinical features of congenital diaphragmatic hernia

Answer 35

Structures displaced to one side Scaphoid abdomen Absent breath sounds

Question 36

Management of congenital diaphragmatic hernia

Answer 36

Surgical repair