Embryology 2

Question 1

What are the two different blood vessel development methods?

Answer 1

Vasculogenesis

and Angiogenesis

Question 2

Define Vasculogenesis

Answer 2

defined as the new formation of a primitive vascular network

Question 3

Define Angiogenesis

Answer 3

defined as the growth of new vessels from pre-existing blood vessels

Question 4

Where do the first arteries appear?

Answer 4

First arteries to appear in the embryo – right and left primitive aortae

Question 5

What does each primitive aorta have?

Answer 5

Each primitive aorta has a ventral part (ventral aorta) and a dorsal part (dorsal aorta)

Question 6

How do aortic arches form?

Answer 6

Pharyngeal arteries communicate with aortic branches; these now called aortic arches

Question 7

How many aortic arches are formed when in communication with the dorsal aortae?

Answer 7

6 aortic arches

Question 8

Where do the 6 pairs of aortic arches develop from?

Answer 8

Aortic branches and pharyngeal arch arteries

Question 9

Where do the 6 pairs of aortic arches terminate at?

Answer 9

Dorsal aorta

Question 10

What is the fate of arches 1 and 2?

Answer 10

The1stand2nd archesdisappear early, remnant of the 1st arch forms part of the maxillary artery (branch of external carotid a.)

*dont worry about maxillary

Question 11

What is the fate of the 3rd arch?

Answer 11

The3rd aortic archconstitutes the commencement of theinternal carotid a., and is therefore named thecarotid arch

Question 12

What is the fate of the left and right 4th arch? *important

Answer 12

The4th right archforms theright subclavian,

The 4th left arch constitutes thedistal part of aortic arch

Question 13

What is the fate of arch 5?

Answer 13

The5th archeither never forms or forms incompletely and then regresses.

Question 14

What is the fate of right arch 6?

Answer 14

The proximal part of the6th right archpersists as the proximal part of the rightpulmonary artery

Question 15

What is the fate of left arch 6

Answer 15

The6th left archgives off the leftpulmonary a.and forms the ductus arteriosus; within 1–3 months, the ductus* is obliterated and becomes the ligamentum arteriosum

*important

Question 16

Why do some great arteries anaomalies arise?

Answer 16

Most defects of the great arteries arise as a result of persistence of aortic arches that normally should regress or regression of arches that normally shouldn’t.

Question 17

Define aberrant subclavian artery

Answer 17

with regression of the right aortic arch 4 and the right dorsal aorta, the rightsubclavian arterysometimes has an abnormal origin on the left side. To supply blood to the right arm, this forces the right subclavian artery to cross the midline behind thetrachea and oesophagus, which may constrict these organs, although usually with no clinical symptoms.

Question 18

Describe a double aortic arch

Answer 18

occurs with the non-regression of the right aortic arch – ie., an abnormal right aortic arch in addition to the left aortic arch - forming a vascular ring around the trachea and oesophagus, which usually causes difficulty in breathing and swallowing.

Question 19

What is a common anaomly associated with maternal rubella infection

Answer 19

patent ductus arteriosus

Question 20

What is the cause of patent ductus arteriosus?

Answer 20

Cause – Failure of muscular wall to contract, respiratory distress syndrome (Low O2) and lack of surfactant in the lungs

Question 21

Define what coarctation of aorta is?

Answer 21

Coarctation of the Aorta; a congenital condition wherein theaortais narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts

Question 22

Which 3 embryonic circulations are present in the fetus?

Answer 22

Umbilical = placental        Cardinal = rest of body
Vitelline = yolk sac

Question 23

What is the fate of umbilical arteries before birth?

Answer 23

Paired branches of the dorsal

aorta to placenta

Question 24

What is the fate of umbilical arteries after birth?

Answer 24

After birth -

Proximal portion persists as internal iliac and superior vesical branches to urinary bladder

Question 25

What is the fate of cardinal veins?

Answer 25

Main venous drainage system of the embryo

Form vena caval (SVC and IVC) system by anastomosis among the veins

Question 26

How can double inferior vena cava arise?

Answer 26

At lumbar level arising from the persistence of the left sarcocardinal vein

Question 27

How can absent inferior vena cava arise?

Answer 27

The lower half of the body is drained by the azygous vein which enters the superior vena cava. .

Question 28

How many primary lymph sacs develop at the end of the embryonic peroid?

Answer 28

six

Question 29

How many bypass shunts does the lung have before birth?

Answer 29

2

Question 30

How many bypass shunts does the liver have before birth?

Answer 30

1

Question 31

What are the 3 foetal circulation shunts?

Answer 31

Ductus venosus
Oval foramen
Ductus arteriosus

Question 32

Describe the blood flow for ductus venosus and what its function

Answer 32

shunts left umbilical vein blood flow directly to IVC: allows oxygenated blood from the placenta to bypass the liver

Question 33

Describe the blood flow for oval foramen and its function

Answer 33

allows blood to enter the leftatriumfrom the right atrium: allows blood to bypass the lungs

Question 34

Describe the blood flow for ductus arteriosus and its function

Answer 34

allows blood that still escapes to the right ventricle to bypass thelungs

Question 35

In terms of neonatal circulation changes after birth, what does the ductus venosus become?

Answer 35

becomes the ligamentum venosum of the liver

Question 36

In terms of neonatal circulation changes after birth, what does the oval foramen become?

Answer 36

closes after birth by tissue proliferation and adhesion of septal structures -> fossa ovalis

Question 37

In terms of neonatal circulation changes after birth, what does the ductus arteriosus become?

Answer 37

obliterates to form ligamentum arteriosum

Question 38

In term of neonatal circulation changes after birth, what does the umbilical arteries become?

Answer 38

ligamentous - medial umbilical ligaments