Embryology 2

Question 1

define vasculogenesis

Answer 1

the new formation of a primitive vascular network

Question 2

define angiogenesis

Answer 2

growth of new vessels from pre-existing blood vessels

Question 3

fate of the 1st and 2nd aortic arches

Answer 3

become the maxillary arteries

Question 4

fate of the third aortic arch

Answer 4

Common carotid and first part of internal carotid arteries

Question 5

fate of the 4th aortic arch on the left side

Answer 5

arch of the aorta (Distal portion)

Question 6

fate of the 4th aortic arch on the right side

Answer 6

Right subclavian artery (proximal portion)

Question 7

fate of the 6th aortic arch on the right side

Answer 7

Becomes right pulmonary artery

Question 8

fate of the 6th aortic arch on the left side

Answer 8

Becomes left pulmonary artery and ductus arteriosus

Question 9

what happens to the 5th aortic arch

Answer 9

either never forms or form incompletely and then disappears

Question 10

when does the lymphatic system develop

Answer 10

at the end of the 6th week develops around main veins

Question 11

what are the first arteries to appear in the embryo?

Answer 11

left and right primitive aortae - each primitive aortae has a ventral and dorsal part

Question 12

after the fusion of 2 endothelial tubes… the 2 ventral aortae partially fuse to from what?

Answer 12

aortic sac

Question 13

how many aortic arch pairs are formed

Answer 13

6

Question 14

what do most defects of the great arteries arise as a result of? (2)

Answer 14

persistence of aortic arches that normally should regress or regression of arches that normally shouldn’t

Question 15

what is aberrant (abnormal) subclavian artery

Answer 15

a rare congenital anomaly that usually does not produce symptoms vascular anomaly of the aortic arch right subclavian artery 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 the trachea and oesophagus, which may constrict these organs

Question 16

double aortic arch - watch out for in OSPE

Answer 16

another congenital aortic arch anomaly occurs with the development of 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 breathing and swallowing.

Question 17

Patent ductus anteriosus PDA

Answer 17

ductus arteriosus fails to close after birth 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 congestive heart failure with increasing age. females > males common link with maternal rubella infection can be genetic or incidental

Question 18

coarctation of the aorta

Answer 18

congenital condition aorta is narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression- connects pulmonary artery with aorta) inserts. The word “coarctation” means narrowing. Coarctations are most common in the aortic arch. Can be proximal to ductus arteriosus (preductal) or distal to it (postductal). (Co = Coarctation site).

Question 19

what are the 3 major areas of embryo

Answer 19

yolk sac placenta aortic arch area

Question 20

names of circulations for:- 1. yolk sac 2. placental 3. rest of body

Answer 20

1. vitelline 2. umbilical 3. cardinal

Question 21

what is the fate of the vitelline arteries in embryo vs adult?

Answer 21

In embryo vitelline arteries supply the yolk sac In adult are represented by arteries to the foregut, midgut & hindgut

Question 22

umbilical arteries before and after birth

Answer 22

Before birth:- Paired branches of the dorsal aorta to placenta After birth:- Proximal portion persists as internal iliac and superior vesical branches to urinary bladder

Question 23

embryonic venous system

Answer 23

Vitelline veins – Carrying blood from the yolk sac to the sinus venosus Umbilical veins – originate from chorionic villi of placenta carrying oxygenated blood to the embryo Cardinal veins – draining the body of embryo

Question 24

where do vitelline, umbilical and cardinal veins drain to?

Answer 24

the right atrium

Question 25

Discuss cardinal veins

Answer 25

Main venous drainage system of the embryo - carry the blood from the head and the lower body into the heart System consists of – anterior, posterior & common cardinal veins draining to sinus venosus Form vena cava (SVC and IVC) system by anastomosis among the veins

Question 26

Venous system abnormalities (4)

Answer 26

double IVC abscence of IVC left SVC double SVC

Question 27

Discuss the development of the lymphatic system

Answer 27

develops at the end of week 6 there are 6 primary lymph sacs at the end of embyronic period lymphatic vessels/channel will join the lymph sacs later

Question 28

why do you no longer need to shunt blood through the heart after a child is born?

Answer 28

because the child can breath so pulmonary circulation kicks in ductus arteriosus is shut off so blood doesn’t move from RA to LA anymore

Question 29

what is good respiration in neonate dependent on?

Answer 29

a normal circulatory transition at birth (placental circulation to pulmonary circulation)

Question 30

what does the ductus venosus do pre birth and why is it shut after birth?

Answer 30

pre birth:- it shunts left umbilical vein blood flow directly to IVC which allows oxygenated blood from the placenta to bypass the liver When you are born you use your liver so this duct that bypassed the liver is shut off.

Question 31

oval foramen pre and post birth

Answer 31

before it allows blood to enter the LA from the RA which allows blood to bypass the lungs don’t need this bypass after birth as lungs should be fully functioning

Question 32

what is the ductus arteriosus and what does it bypass

Answer 32

a blood vessel connecting the main pulmonary artery to the proximal descending aorta. It allows most of the blood from the right ventricle to bypass the foetus’s fluid-filled non-functioning lungs.

Question 33

state the pathway of blood from aorta to umbilical vein in foetus

Answer 33

Aorta descending aorta abdominal aorta common iliac artery umbilical arteries placenta umbilical vein

Question 34

what happens to foramen ovale, ductus venosus and ductus arteriosus at birth?

Answer 34

they are all shut off

Question 35

what does the ductus venosus become

Answer 35

it constricts and becomes solid the ligamentum venosum of the liver

Question 36

what does the ductus arteriosus become

Answer 36

it constricts and becomes solid ligamentum arteriosum (small ligament)

Question 37

Cause of patent ductus arteriosus

Answer 37

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