Development of cardio/pulm Flashcards
In what direction does the laryngeotracheal diverticulum grow?
distally, and is separated from the esophagus by the tracheoesophageal septum
What is tracheoesophageal fistula?
- most common abnormality
2. improper formation of the tracheoesophageal septum
What is an esophageal atresia, and can this accompany a tracheoesophageal fistula?
- failure of the esophagus to properly form with the stomach.
- yes
What would be associated with EA, and TEF?
polyhydramnios, baby will not be able to swallow, and if so it will not be able to pas to the stomach
When do the trachea divide into the 2 bronchial buds?
week 4, which will become the primary bronchi
When do secondary bronchial buds form?
week 5 followed by the tertiary at week 6
What tissue differentiates into the smooth muscle, nerves, and blood vessels of the lungs?
splanchnic mesoderm
What are the stages and time periods of lung development?
- embryonic (4-7wk)
- pseudoglandular (8-16wk)
- CANALICULAR (17-26wk)
- terminal sac (26wk to birth)
- postnatal (alveolar)
What forms during the embryonic stage of development at weeks 4-7?
- respiratory diverticulum and major bronchopulmonary segments
- lung grow into pleural cavity
- pleura differentiates
What forms during the pseudo glandular stage, 8-16wks?
- duct system of bronchopulmonary segment
2. no respiratory components
What forms during canalicular stage, 17-26wks?
- respiratory bronchioles and terminal sacs
- increased vascularization
- capillaries develop in walls
- earliest possibly survivable birth
What happens during the terminal sacular stage? 26wk to birth?
- alveoli develop from respiratory bronchioles
2. epithelial lining differentiates into two cell types
What are the type I and type II pneumocytes used for in the lungs?
- type I: form air-blood barrier
2. type II: secrete surfactant, aids in alveolar expansion
What occurs in the postnatal stage of development?
- 90% alveoli form via septation of pre-existing alveoli
What can lead to infant respiratory distress syndrome, via immature or damaged type II pneumocytes?
- premature
How can low surfactant levels lead to IRDS?
causes lung collapse which causes hypoxia and sometimes death
Describe pulmonary agenesis
-absence of lung, bronchi and vasculature
Describe pulmonary hypoplasia
small segment of lung. underdeveloped
What is a congenital diaphragmatic hernia?
abdominal contents extend through the diaphragm into the thoracic cavity. Prone to pulmonary hypoplasia
Where are congenital diaphragmatic hernias most commonly found?
- posterolateral left side
- results when the pleuroperitoneal membranes do not fuse properly
What are some simple ways to detect congenital diaphragmatic hernias?
- flat abdomen, brethlessness that resolves with sitting upright.
- cyanosis
What vessels does blood drain out of the heart by in the developing fetus?
anterior and posterior cardinal veins that drain into the common cardinal vein
What is considered the nursery for blood cells?
The vitelline which supplies and drains the yolk sac
What does the sinus venosus become in the adult?
smooth portion of Rt atrium, coronary sinus, oblique vein of Lt atrium
What does the primitive atrium become in an adult?
trabeculated part of L and R atria (auricles)
What does the primitive ventricle become in the adult?
trabeculated L and R ventricles
What does the bulbus cordis become in the adult?
smooth portion of R ventricle (sonus cordis) and of L ventricle (aortic vestibule)
What does the truncus arteriosus become in the adult?
aorta, pulmonary trunk
What is dextrocardia?
the heart folds to the left instead of the right, causing it to displace to the right side. great vessels also translocate
What forms the endocardial cushions? ECC
growing together of the dorsal and ventral blocks of tissue. this forms the L and R AV canals
What is an atrioventricular communis?
if the ECC fails to fuse, this is the result and failure of L and R AV canals
Ventricular Septal Defects (VSDs) develop in how many steps and what is this defect?
- upgrowth with the septum and fusion with a membranous portion which is most common to lead to this disease.
- allows shunting of blood between the L and R ventricles
How does the atrial septum form?
septum primum grows to the ECC, it separates from the base, forming two passageways. the foramen primum closes, and the foramen secundum slowly begins to close.
-as the foramen secundum closes the tissues are offest, in order to form a flap to allow blood flow from R atrium to L atrium, bypassing the lungs
How does blood bypass the lungs in the developing fetus?
the foramen ovale acts like a gate based on pressure flow. R atrial pressure> L atrial pressure causing blood to flow from R to L bypassing the lungs.
-inhalation causes the pressure gradient to flip and theoretically should close the foramen ovale
What system do the vitelline veins become incorporated?
they become hepatic sinusoids, heptic veins, portion of the IVC, and drain some of the GI tract
What is the role of the ductus venosus?
Connects the umbilical vein with the IVC, and bypasses the liver. provides oxygenated blood to the heart
Where does the SVC come from?
R anterior and common cardinal veins
What is tetralogy of fallot?
a VSD, with pulmonary stenosis and R ventricular hypertrophy
What is a patent ductus arteriosus?
allows mixing of blood from the aorta and the pulmonary artery. causes mixing of oxygenated and deoxygenated blood
At what point in development do type II pneumocytes develop?
week 12-13
At what point of development at type I pneumocytes present and allow potential for a viable birth?
week 20
