Embryology

Question 1

How does the AP septum formed?

Answer 1

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.

Question 2

How does the interventricular septum form?

Answer 2

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.

Question 3

How does the foramen ovale form?

Answer 3

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.

Question 4

What does the foramen ovale become?

Answer 4

Fossa ovale

Question 5

What is intussusception?

Answer 5

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.

Question 6

What do the primitive atria become?

Answer 6

Trabeculated atria and auricles

Question 7

What does the bulbis cords become?

Answer 7

The smoother parts of the right atria and outflow track

Question 8

What does the primitive ventricle become?

Answer 8

The left ventricle and rough parts of the right ventricle

Question 9

What do the right and left sinus venosus become?

Answer 9

The right sinus venosus becomes the smooth wall of the right atria. The left sinus venous becomes the coronary sinus.

Question 10

What forms the trachea?

Answer 10

16-20 cartilaginous rings and posterior, the trachealis muscle

Question 11

When do most of the alveoli form?

Answer 11

After birth, because the trachea bifurcates 23 times before birth 4 additional times after birth, for a total of 27 bifurcations.

Question 12

What are bronchioles?

Answer 12

Tubes without cartilage

Question 13

What part of the gut does the lung derive from?

Answer 13

The foregut

Question 14

What are some clinical correlates related to the poor formation of the tracheal esophageal septum?

Answer 14

Fistulas and atresias. Atresias can lead to aspiration. Fistulas can lead to air in the gut.

Question 15

What is the relationships between the mesenchyme of the mesoderm and the epithelium and the endoderm in the formation of the lungs?

Answer 15

The mesenchyme sends signals to the epithelium which become the lungs.

Question 16

Explain the roles of the following in lung bud development: FGF-10, BMP4, and TGFbeta.

Answer 16

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.

Question 17

How does epithelium establish polarity in the developing lung?

Answer 17

epimorphin is secreted by the surrounding mesenchyme

Question 18

What is the role of tenascin and syndecan in lung development?

Answer 18

They signal to the epithelium to grow in sheets.

Question 19

What is the sequential order of stages of lung development?

Answer 19

Embryonic, pseudoglandular, canallcular, saccular, alveolar

Question 20

When is lung surfactant made?

Answer 20

Week 25

Question 21

Which is developed first - the maternal circulation to the placenta or the fetal circulation in the placenta?

Answer 21

Maternal

Question 22

What is the role of FGF8 and retinoic acid in the formation of cardiac tissue?

Answer 22

Mesoderm passes through gradients of these chemicals determining what part of the heart they will become.

Question 23

Contrast angiogenesis and vasculogenesis.

Answer 23

Vasculogenesis is the generation of new blood vessels (V for de noVo) and angiogenesis is the generation of branches off of existing blood vessels

Question 24

What prevents the heart from kinking with cardiac looping?

Answer 24

cardiac jelly

Question 25

How do the valves of the heart form?

Answer 25

Valves of the heart are derived from thickened mesenchyme which came from the formation of endocardial cushions.

Question 26

How did the IV septa form?

Answer 26

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.

Question 27

What is the role of adherons in the formation of the heart?

Answer 27

Still unclear on this!

Question 28

What cells are responsible for the formation of the AP septa?

Answer 28

Neural crest cells and cells from the secondary heart field.

Question 29

How do chordae tendinae form?

Answer 29

Muscular portions of the ventricles disappear leaving behind these chordae tendinae.

Question 30

Describe the aortic arches?

Answer 30

How often does this appear on the boards?

Question 31

What causes patent ductus arteriosum?

Answer 31

Normally at birth, prostaglandin levels E1 and E2 drop; however, if they do not drop then patent ductus arteriosum can occur.

Question 32

Describe patent foramen ovale.

Answer 32

Present in 20-25% of the population. Is usually functionally and is first noticed often with changes in altitude.

Question 33

What is the most common septal defect?

Answer 33

VSD

Question 34

Cortication of the aorta

Answer 34

Narrowing of the aorta

Question 35

Transposition of the great vessels

Answer 35

Switching of the pulmonary and the aorta. This can be somewhat alleviated if coupled with a VSD.

Question 36

Tetratology of fallot

Answer 36

Overriding aorta, pulmonary stenosis, VSD, RV hypertrophy. Clinical sign is usually a child hunched over.