Lecture 5: Cardiopulmonary Development

Question 1

Early phase of lung development

Answer 1

Positioning of lung primordium and primary lung bud formation

Question 2

Late phase of lung development

Answer 2

Mechanism of bronchial branching and cytodifferentiation

Question 3

What signaling molecule specifies the respiratory diverticulum’s position, growth, and development?

Answer 3

Tbx4

Question 4

Tracheoesophageal fistula

Answer 4

Most common respiratory malformation; abnormal communication between trachea/esophagus caused by improper formation of tracheoesophageal septum

Question 5

What is the primary tissue from which the smooth muscle, nerves and blood vessels of the lungs differentiate?

Answer 5

Splanchnic mesoderm

Question 6

Which stage in lung development will the lungs have enough tissue for the embryo to be viable at birth?

Answer 6

Canalicular stage

Question 7

Embryonic stage (lung development)

Answer 7

Weeks 4-7; respiratory diverticulum forms and major bronchopulmonary segments formed

Question 8

Pseudoglandular stage (lung development)

Answer 8

Weeks 8-16; formation and growth of duct systems within bronchopulmonary segments - resembles a “gland”

Question 9

Canalicular stage (lung development)

Answer 9

Weeks 17-26; formation of respiratory bronchioles and terminal sacs (primitive alveoli); vascularization increases, capillaries found in walls - embryo may be viable at this point

Question 10

Terminal sac stage (lung development)

Answer 10

Weeks 27-birth; Alveoli begin to develop from respiratory bronchioles; epithelium lining alveoli differentiates into type I, II pneumocytes

Question 11

Type I pneumocyte

Answer 11

Form part of the blood-air barrier; stem cells for type II

Question 12

Type II pneumocyte

Answer 12

Secrete Clara cells that produce surfactant

Question 13

What are the 3 pulmonary components needed for an embryo to be viable at birth?

Answer 13

Alveoli, pneumocytes/surfactant, capillaries

Question 14

Postnatal/Alveolar stage (lung development)

Answer 14

Up to 90% alveoli formed after birth via septation of pre-existing alveoli

Question 15

Infant Respiratory Distress Syndrome (IRDS)

Answer 15

Deficiency/absence of surfactant; causes labored breathing, results in incomplete expansion or collapse of parts or whole lung

Question 16

Pulmonary agenesis

Answer 16

Complete absence of lungs, bronchi, vasculature - lung buds do not develop; can be bilateral (poor prognosis) or unilateral (better prognosis)

Question 17

Pulmonary hypoplasia

Answer 17

Poorly developed bronchial tree affecting partial or total lung

Question 18

Congenital diaphragmatic hernia

Answer 18

Abdominal contents herniated into thoracic cavity; can cause pulmonary hypoplasia; caused by failure of pleuroperitoneal membranes to fuse; signs: unusually flat abdomen, breathlessness, cyanosis

Question 19

What systems empty into the primitive heart?

Answer 19

Vitelline, Umbilical, and Common Cardinal systems

Question 20

What adult structures does the truncus arteriosus give rise to?

Answer 20

Aorta, pulmonary trunk

Question 21

What adult structures does the bulbus cordis give rise to?

Answer 21

Smooth part of right ventricle, smooth part of left ventricle

Question 22

What adult structures does the primitive ventricle give rise to?

Answer 22

Trabeculated part of right and left ventricles

Question 23

What adult structures does the primitive atrium give rise to?

Answer 23

Trabeculated part of right and left atria (auricles)

Question 24

What adult structures does the sinus venosus give rise to?

Answer 24

Smooth part of right atrium, coronary sinus, oblique vein of left atrium

Question 25

Dextrocardia

Answer 25

Heart bends to the left instead of the right; may be asymptomatic

Question 26

Atrioventricular communis

Answer 26

Large communication between chambers that occurs when cushions fail to fuse

Question 27

Ventricular Septal Defects (VSDs)

Answer 27

Opening between the L/R ventricles associated with shunting of blood; most VSDs requiring surgical correction occur in membranous portion

Question 28

Atrial Septal Defects (ASDs)

Answer 28

Ostium primum defects; secundum type involves foramen ovale and septum primum, sinus venosus - usually near opening of SVC

Question 29

Vitelline vein shunt

Answer 29

Veins become incorporated into liver as hepatic sinusoids, hepatic veins, part of IVC, and GI structures

Question 30

Umbilical vein shunt

Answer 30

Obliterated umbilical vein = ligamentum teres hepatis; umbilical vein connected with IVC

Question 31

Ductus venosus

Answer 31

Connects umbilical vein with IVC, bypasses liver and diverts oxygenated blood into heart

Question 32

Shunt for cardinal system

Answer 32

Anterior cardinal veins are connected, anastomosis becomes left brachiocephalic vein; right anterior cardinal and common cardinal veins become SVC

Question 33

Tetralogy of Fallot

Answer 33

Pulmonary stenosis, VSD, overriding aorta, R Ventricular hypertrophy

Question 34

Patent ductus arteriosus

Answer 34

Abnormal connection between the aorta and the pulmonary artery in the heart - ductus arteriosus remains open after birth