Lecture 5: Cardiopulmonary Development Flashcards
Early phase of lung development
Positioning of lung primordium and primary lung bud formation
Late phase of lung development
Mechanism of bronchial branching and cytodifferentiation
What signaling molecule specifies the respiratory diverticulum’s position, growth, and development?
Tbx4
Tracheoesophageal fistula
Most common respiratory malformation; abnormal communication between trachea/esophagus caused by improper formation of tracheoesophageal septum
What is the primary tissue from which the smooth muscle, nerves and blood vessels of the lungs differentiate?
Splanchnic mesoderm
Which stage in lung development will the lungs have enough tissue for the embryo to be viable at birth?
Canalicular stage
Embryonic stage (lung development)
Weeks 4-7; respiratory diverticulum forms and major bronchopulmonary segments formed
Pseudoglandular stage (lung development)
Weeks 8-16; formation and growth of duct systems within bronchopulmonary segments - resembles a “gland”
Canalicular stage (lung development)
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
Terminal sac stage (lung development)
Weeks 27-birth; Alveoli begin to develop from respiratory bronchioles; epithelium lining alveoli differentiates into type I, II pneumocytes
Type I pneumocyte
Form part of the blood-air barrier; stem cells for type II
Type II pneumocyte
Secrete Clara cells that produce surfactant
What are the 3 pulmonary components needed for an embryo to be viable at birth?
Alveoli, pneumocytes/surfactant, capillaries
Postnatal/Alveolar stage (lung development)
Up to 90% alveoli formed after birth via septation of pre-existing alveoli
Infant Respiratory Distress Syndrome (IRDS)
Deficiency/absence of surfactant; causes labored breathing, results in incomplete expansion or collapse of parts or whole lung
Pulmonary agenesis
Complete absence of lungs, bronchi, vasculature - lung buds do not develop; can be bilateral (poor prognosis) or unilateral (better prognosis)
Pulmonary hypoplasia
Poorly developed bronchial tree affecting partial or total lung
Congenital diaphragmatic hernia
Abdominal contents herniated into thoracic cavity; can cause pulmonary hypoplasia; caused by failure of pleuroperitoneal membranes to fuse; signs: unusually flat abdomen, breathlessness, cyanosis
What systems empty into the primitive heart?
Vitelline, Umbilical, and Common Cardinal systems
What adult structures does the truncus arteriosus give rise to?
Aorta, pulmonary trunk
What adult structures does the bulbus cordis give rise to?
Smooth part of right ventricle, smooth part of left ventricle
What adult structures does the primitive ventricle give rise to?
Trabeculated part of right and left ventricles
What adult structures does the primitive atrium give rise to?
Trabeculated part of right and left atria (auricles)
What adult structures does the sinus venosus give rise to?
Smooth part of right atrium, coronary sinus, oblique vein of left atrium
Dextrocardia
Heart bends to the left instead of the right; may be asymptomatic
Atrioventricular communis
Large communication between chambers that occurs when cushions fail to fuse
Ventricular Septal Defects (VSDs)
Opening between the L/R ventricles associated with shunting of blood; most VSDs requiring surgical correction occur in membranous portion
Atrial Septal Defects (ASDs)
Ostium primum defects; secundum type involves foramen ovale and septum primum, sinus venosus - usually near opening of SVC
Vitelline vein shunt
Veins become incorporated into liver as hepatic sinusoids, hepatic veins, part of IVC, and GI structures
Umbilical vein shunt
Obliterated umbilical vein = ligamentum teres hepatis; umbilical vein connected with IVC
Ductus venosus
Connects umbilical vein with IVC, bypasses liver and diverts oxygenated blood into heart
Shunt for cardinal system
Anterior cardinal veins are connected, anastomosis becomes left brachiocephalic vein; right anterior cardinal and common cardinal veins become SVC
Tetralogy of Fallot
Pulmonary stenosis, VSD, overriding aorta, R Ventricular hypertrophy
Patent ductus arteriosus
Abnormal connection between the aorta and the pulmonary artery in the heart - ductus arteriosus remains open after birth
