Embryology Flashcards
How does the AP septum formed?
Neural crest cells and the secondary heart field cells migrate to form a 180 degree clockwise septa dividing the outflow tracks. This contributes to the membranous portion of the inter ventricular septum.
How does the interventricular septum form?
The muscular portion of the interventricular septum naturally grows as the ventricles expand. The membraneous portion of the interventricular septum forms from the AP septum formation.
How does the foramen ovale form?
The septum primum expands down superiorly to inferiorly. There is a osmium primum and an osmium secundum that forms with the blood flood shooting from the inferior vena cava. This is the flimsy septum that eventually will become the flap. The septum secundum forms inferiorly to superiorly from anterior to posterior. This is the firm septum.
What does the foramen ovale become?
Fossa ovale
What is intussusception?
The intake of vessels into the heart that forms the smooth walls of the heart. The right sinus venosus makes the smooth part of the right atria and the pulmonary veins make the smooth part of the left atria.
What do the primitive atria become?
Trabeculated atria and auricles
What does the bulbis cords become?
The smoother parts of the right atria and outflow track
What does the primitive ventricle become?
The left ventricle and rough parts of the right ventricle
What do the right and left sinus venosus become?
The right sinus venosus becomes the smooth wall of the right atria. The left sinus venous becomes the coronary sinus.
What forms the trachea?
16-20 cartilaginous rings and posterior, the trachealis muscle
When do most of the alveoli form?
After birth, because the trachea bifurcates 23 times before birth 4 additional times after birth, for a total of 27 bifurcations.
What are bronchioles?
Tubes without cartilage
What part of the gut does the lung derive from?
The foregut
What are some clinical correlates related to the poor formation of the tracheal esophageal septum?
Fistulas and atresias. Atresias can lead to aspiration. Fistulas can lead to air in the gut.
What is the relationships between the mesenchyme of the mesoderm and the epithelium and the endoderm in the formation of the lungs?
The mesenchyme sends signals to the epithelium which become the lungs.
Explain the roles of the following in lung bud development: FGF-10, BMP4, and TGFbeta.
FGF-10 is a signal molecule from the mesenchyme that allows the epithelia to grow. BMP4 inhibits FGF-10, preventing growth at branching points. Shh causes the release of TGFbeta which causes collagen production at these branching points.
How does epithelium establish polarity in the developing lung?
epimorphin is secreted by the surrounding mesenchyme
What is the role of tenascin and syndecan in lung development?
They signal to the epithelium to grow in sheets.
What is the sequential order of stages of lung development?
Embryonic, pseudoglandular, canallcular, saccular, alveolar
When is lung surfactant made?
Week 25
Which is developed first - the maternal circulation to the placenta or the fetal circulation in the placenta?
Maternal
What is the role of FGF8 and retinoic acid in the formation of cardiac tissue?
Mesoderm passes through gradients of these chemicals determining what part of the heart they will become.
Contrast angiogenesis and vasculogenesis.
Vasculogenesis is the generation of new blood vessels (V for de noVo) and angiogenesis is the generation of branches off of existing blood vessels
What prevents the heart from kinking with cardiac looping?
cardiac jelly
How do the valves of the heart form?
Valves of the heart are derived from thickened mesenchyme which came from the formation of endocardial cushions.
How did the IV septa form?
The IV septa first forms with the muscular portion that grows naturally as the ventricles expand. The membranous portion is the part that forms along with the AP septa. This is the part of the septa that is most frequently deformed for this reason.
What is the role of adherons in the formation of the heart?
Still unclear on this!
What cells are responsible for the formation of the AP septa?
Neural crest cells and cells from the secondary heart field.
How do chordae tendinae form?
Muscular portions of the ventricles disappear leaving behind these chordae tendinae.
Describe the aortic arches?
How often does this appear on the boards?
What causes patent ductus arteriosum?
Normally at birth, prostaglandin levels E1 and E2 drop; however, if they do not drop then patent ductus arteriosum can occur.
Describe patent foramen ovale.
Present in 20-25% of the population. Is usually functionally and is first noticed often with changes in altitude.
What is the most common septal defect?
VSD
Cortication of the aorta
Narrowing of the aorta
Transposition of the great vessels
Switching of the pulmonary and the aorta. This can be somewhat alleviated if coupled with a VSD.
Tetratology of fallot
Overriding aorta, pulmonary stenosis, VSD, RV hypertrophy. Clinical sign is usually a child hunched over.
