Embryology of the CVS 2 ND

Question 1

What are the two ways the blood vessels develop?

Answer 1

Vasculogenesis
- defined as the new formation of a primitive vascular network

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

Question 2

The aortic sac is an extension of which part of the primitive heart tube?

Answer 2

Truncus arteriosis

Question 3

How does the aortic sac form?

Answer 3

Fusion of the ventral part of the left and right aortae

when the two heart tubes fuse together to form the single heart tube

Question 4

What are the first arteries to appear in the embryo?

Answer 4

Left and right primitive aortae

Question 5

Describe the appearance of the primitive aortae

Answer 5

Have a ventral part that arches over into a dorsal part

Question 6

What happens after the fusion of the aortae to form the aortic sac?

Answer 6

Aortic branches arise from the aortic sac

6 on either side

Question 7

When do the pharyngeal arches develop?

Answer 7

4th & 5th week

Question 8

After formation of the pharyngeal arches, what happens involving the aortic branches?

Answer 8

Each pharyngeal arch has its own nerve and artery

The pharyngeal arch arteries join with the aortic branches

This forms the 6 AORTIC ARCHES on each side, which connect the dorsal aorta to the ventral aorta on either side

However, they are not all present at the same time

Question 9

What is the fate of the 1st aortic arches?

Answer 9

It disappears

A remnant of the 1st arch forms part of the maxillary artery (branch of external carotid a.)

Question 10

What is the fate of the 2nd aortic arches?

Answer 10

It disappears

Question 11

What is the fate of the 3rd aortic arches?

Answer 11

Internal carotid artery

hence it is sometimes called the carotid arch

Question 12

What is the fate of the 4th aortic arches?

Answer 12

Right 4th = Right subclavian

Left 4th = Aortic arch

Question 13

What is the fate of the 5th aortic arches?

Answer 13

5th arch either never forms or forms incompletely and then regresses

Question 14

What is the fate of the 6th aortic arches?

Answer 14

The proximal part of the sixth right arch persists as the proximal part of the right pulmonary artery while the distal section degenerates

The sixth left arch gives off the left pulmonary artery and forms the ductus arteriosus

Question 15

What is the ductus arteriosus and what happens to it?

Answer 15

Little tube thing connecting pulmonary artery to aorta

It turns into ligamentum arteriosum between 1-3 months after birth

Question 16

What generally causes abnormalities in the great arteries?

Answer 16

Persistence of aortic arches that normally should regress

or

Regression of arches that normally shouldn’t.

Question 17

Give examples of congenital abnormalities in the great arteries

Answer 17

Aberrant subclavian artery

Double aortic arch

Patent ductus arteriosus(PDA)

Coarctation of the Aorta

Question 18

What is an aberrant subclavian artery?

Answer 18

rightsubclavian arteryhas 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

may constrict these organs, although usually with no clinical symptoms

Question 19

What is a double aortic arch?

Answer 19

Aorta with two arches, with the trachea and oesophagus passing through the hole in between the two arches

Difficulty breathing and swallowing

Question 20

What is Patent ductus arteriosus (PDA)?

Answer 20

Ductus arteriosusfails to close afterbirth

Early symptoms are uncommon, but in the first year of life include increased ‘work of breathing’ and poor weight gain

An uncorrected PDA may lead to congestiveheart failurewith increasing age.

Question 21

What is Coartication of the aorta?

Answer 21

Congenital condition wherein theaortais narrow

Usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts

Can be proximal to ductus arteriosus (preductal) or distal to it (postductal

Question 22

What are the 3 main circulations in an emrbyo

Answer 22

Vitelline = yolk sac

Umbilical = placental

Cardinal = rest of body

Question 23

What is the fate of the vitelline arteries?

Answer 23

In adult are represented by arteries to the foregut, midgut & hindgut

Question 24

What is the structure of the umbillical arteries before birth ?

Answer 24

Paired branches of the dorsal aorta to placenta

Question 25

What is the fate of the umbillical arteries?

Answer 25

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

Question 26

Where do all embryonic veins enter?

Answer 26

Sinus venosus

Question 27

Which venous system in the embryo is the largest?

Answer 27

Cardinal venous system

Question 28

Describe the different cardinal veins

Answer 28

System consists of – anterior, posterior & common cardinal veins draining to sinus venosus

Question 29

What is the fate of the cardinal venous system?

Answer 29

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

Question 30

Give some examples of abnormalities with development of the venous system

Answer 30

Double IVC

Absence of IVC

Left SVC

Double SVC

Question 31

How/when does the lymphatic system develop?

Answer 31

Develops at the end of sixth week around main veins

Six primary lymph sacs develops at the end of embryonic period

Lymphatic vessels will join the lymph sacs later

Question 32

When a baby is born, it changes from maternal breathing to independent breathing

Several parts of the CVS are important in this transition

What are they?

Answer 32

Ductus venosus (shunts left umbilical vein blood flow directly to IVC: allows oxygenated blood from the placenta to bypass the liver).

Oval foramen (allows blood to enter the leftatriumfrom the right atrium: allows blood to bypass the lungs).

Ductus arteriosus (allows blood that still escapes to the right ventricle to bypass thelungs).