L29 – Development of the great vessels and circulatory changes at birth Flashcards Preview

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Flashcards in L29 – Development of the great vessels and circulatory changes at birth Deck (96):
1

Define Vasculogenesis

The de novo formation of blood vessels from angioblasts (haemangioblasts)

2

Define Angiogenesis.

growth of new capillaries from pre-existing blood vessels(i.e. dorsal aorta, cardinal vein)

3

Three mechanisms of Angiogenesis?
SIB

1. Sprouting (= branching)
2. Intussusception (= splitting: grow inward into smaller capillaries)
3. Bridging (grow inward but more evenly distributed)

4

Which mechanism of angiogenesis gives increasing number of blood vessels?

Intussusception

5

6 pairs of pharyngeal arches develop. Describe innervation of arches. Describe core of these arches and their function.

Each pharyngeal arch receives its own nerve, artery

Each arch has core of
mesenchyme tissue: give rise to specific tissues in head and neck

6

How do aortic arches arise and where do they terminate?

Arise from aortic sac (distal truncus arteriosus)

Aortic arches are embedded in mesenchyme core of pharyngeal arches

Terminate in L/R dorsal aortae > converge to outflow tract

7

How do pharyngeal arches and aortic arches appear?

Cranial- caudal sequence
Aortic sac contributes a branch to each new pharyngeal arch as it
forms

8

Which pharyngeal arch forms incompletely and degenerates?

5th

9

What happens to the first and second aortic arches by 5th week?

1st and 2nd aortic arches degenerate

1st arch remnant= Maxillary artery

2nd arch remnant= hyoid and stapedial arteries

10

What happens to 3rd, 4th and 6th aortic arches by week 5?

3rd = Large
4th, 6th = Still forming

11

Which arch give rise to primitive pulmonary artery?

developing 6th aortic arch

12

Is the differentiation of aortic arches simultaneous?

No

Graded formation: remodelling from 1st arch to 6th

13

What areas do the aortic arches supply blood to?

3rd = head
4th = head, arms
6th= lung bud

14

Describe further development of 3rd aortic arch.

Left and Right:
Form L/R Common carotid artery
+
Proximal portion of internal carotid artery

15

Describe further development of 4th aortic arch.

Left: Aortic arch (portion between left subclavian and left common carotid artery)
Distal aortic arch connect to L dorsal aorta

Right: Proximal portion of right subclavian
artery > connect to R
dorsal aorta

16

Describe further development of 6th aortic arch.

Left: Left pulmonary artery + Ductus arteriosus

Right: Right pulmonary artery

17

What is role of ductus arteriosus?

Transient, allow blood to bypass lungs to descending aorta

18

Which caudal portion of dorsal aorta is obliterated?

Right dorsal aorta

19

What do vessels in right cranial dorsal aorta lead to?

7th intersegmental artery

20

What duct formed by 3rd aortic arch is obliterated?

Carotid duct

21

Name the vessel that connect 3rd aortic arch with dorsal aorta?

Proximal internal carotid artery on both sides

22

Name the vessel that connect 4th aortic arch with dorsal aorta?

Proximal subclavian artery on right

Distal aortic arch on left

23

Name the vessel that connect 6th aortic arch with dorsal aorta?

Only left dorsal aorta through ductus arteriosus

24

Which vessels are wrongly obliterated/ wrongly persist in Abnormal origin of right subclavian artery?

Wrongly obliterated: Right 4th aortic arch and right proximal dorsal aorta

Wrongly persist: Right distal dorsal aorta

Right subclavian artery wrongly formed by right distal dorsal aorta and 7th intersegmental artery

25

Consequence of abnormal origin of right subclavian artery?

Abnormal right subclavian artery settle below left subclavian artery

Cross midline behind esophagus to reach right arm

Neither esophagus or trachea compressed severely

26

What causes double aortic arch to form?

Wrongly persist: right distal dorsal aorta

vascular ring surrounds,
compresses both
trachea and esophagus
> difficulties in
breathing, swallowing

27

Dorsal aorta branches throughout the embryo. Name A/V for placenta circulation, Vitelline circulation.

Placenta circulation:
 Left umbilical vein
 Umbilical artery

Vitelline circulation :
 Vitelline vein
 Vitelline artery

28

Vitelline arteries (branch of dorsal aorta) differentiates into what vessels of the gut?

Coelian arteries in foregut
Superior mesenteric arteries in mingut

29

What vessel forms artery for hindgut?

Umbilical arteries > inferior mesenteric arteries

30

Role of umbilical arteries?

Originate from chorionic villi, Convey deoxygenated blood to placenta for oxygenation

31

Fate of umbilical arteries at birth?

Proximal portion = superior vesical arteries

Distal portion = medial umbilical ligaments

32

Role of cardinal veins?

Draining body of embryo proper

33

Role of vitelline veins?

Carrying blood from yolk sac to sinus venosus

34

What are the six cardinal veins? What do cardinal veins originate from?

Left and Right Anterior, Common, Posterior cardinal veins

Arise from Left or Right horns of Sinus venosus

35

What cardinal veins drains what part of embryo?

Anterior cardinal vein> drain cephalic part

Posterior cardinal vein > drain rest of embryo

36

How do cardinal veins join?

Anterior and Posterior cardinal veins join at common cardinal veins > enter sinus venosus

37

Route of blood in sinus venosus? receive and opens into what?

Sinus venosus:
 Receives blood from right, left sinus horn
 Opens into primitive
atrium

38

Effects of asymmetrical Left to right shunt of blood in primitive heart?

 Right sinus horn increases in size
 Obliteration of left vitelline vein and left posterior + anterior cardinal veins, right umbilical vein, right posterior common
cardinal vein

39

What vessels are NOT obliterated in the development of sinus venosus before day 50?

left umbilical vein, right anterior + common cardinal vein

40

What vessel obliterated from day 50-56? What remnant of left sinus horn?

Left common cardinal vein obliterates

 remains of left sinus horn = oblique vein of left atrium,
coronary sinus

41

What happens to the initial orifice of pulmonary vein?

becomes 4 orifices of pulmonary veins

42

Fate of right anterior cardinal vein?

right brachiocephalic vein

43

Fate of right posterior cardinal vein?

inferior vena cava

44

Fate of right anterior cardinal vein?

Superior Vena Cava

45

What occurs to form sinus venarum?

Right sinus horn is gradually incorporated/ inserted into right atrium to form sinus venarum (smooth-walled)

46

What is the sinuatrial orifice originally flanked by?

Initially flanked by right, left venous valves

47

What happens to the valves of sinuatrial orifice in development of sinus venosus?

 Superior portion of valves disappear

 Inferior portion develops into:
Valve of inferior vena cava
(drains into RA)
Valve of coronary sinus (drains into RA)

48

What forms to divide the original trabeculated primitive right atrium and the incorporated right sinus horn - sinus venarum?

Crista terminalis forms dividing line between:
 Sinus venarum
 Original trabeculated part of right atrium

49

What initially develops to form single embryonic pulmonary vein? Fate of this single vein?

Posterior left atrial wall grows out = single embryonic pulmonary vein

later: 4 pulmonary veins enter LA

50

Where do vitelline veins arise from?

Arise from capillary plexus of yolk sac

51

Tract of vitelline veins?

Carry blood from yolk sac to sinus venosus, passing liver

Run in each side of duodenum and forms plexus around it > develops into a single vessel (portal vein)

52

What forms hepatic sinosoids?

With development of liver cord (by Week 5): proximal part of vitelline, umbilical veins break into numerous vascular network > form
hepatic sinosoids

53

How are hepatic sinusoids drained?

drain into sinus venosus through right, left hepatocardiac channels to vena cava

54

Explain Selective obliteration to maintain flow back to right atrium by forming common hepatic vein.(Star with left sinus horn obliteration...)

Left sinus horn and hepatocardiac channel obliterated > blood from left umbilical vein enters sinus venosus through right hepatocardiac channel > right vitelline forms common hepatic vein (hepatic portion of inferior VC)

55

What is superior mesenteric vein derived from? How?

Right vitelline vein

Left vitelline vein degenerate, leaving enlarging R. vitelline > portal vein branching into superior mesentery and splenic veins

56

What portions of umbilical veins are obliterated? What remains and enlarges?

Proximal part of both umbilical veins
+
Remainder of right umbilical vein

Left umbilical vein remains and enlarges

57

How does left umbilical vein carry blood from placenta to heart, bypassing liver?

via DUCTUS VENOSUS

ligamentum venosum at birth

58

Anastomosis of what veins form left brachiocephalic vein?

Between anterior cardinal veins

59

How is the left superior intercostal vein formed?

Terminal portion of left posterior cardinal vein entering left brachiocephalic vein retained as left superior intercostal vein

60

What forms superior vena cava?

Right common cardinal vein +
proximal portion of right anterior cardinal vein

61

What does the distal portion of right anterior cardinal vein form?

Right internal jugular vein

62

What forms the azygous vein?

Right supracardinal vein + a portion of posterior cardinal vein

63

What forms the left renal vein?

Anastomosis between subcardinal veins

64

What forms the hemiazygous vein?

Supracardinal vein + left common cardinal vein

65

What does the right subcardinal vein develop into?

develops into renal segment of inferior vena cava

66

What is the fate of left subcardinal vein?

 Proximal: degenerates
 Distal: becomes left gonadal vein

67

What forms left common iliac vein?

Anastomosis between sacrocardinal veins

68

What does Intercostal vein empty into ?

right supracardinal vein

69

What vein becomes hepatic segment of inferior VC?

Right sacrocardinal vein
(left obliterated)

70

What is the fate of Left vitelline vein?

Regresses > disappears

71

Fate of Right vitelline vein?

 Terminal segment of IVC
 Hepatic portal system (Superior mesenteric vein)

72

Fate of Left umbilical vein?

Anastomosis with ductus venosus, connect with placenta

73

Fate of Right umbilical vein?

Regresses > disappears

74

Fate of Left anterior cardinal vein?

 Caudal part: oblique vein of left atrium (coronary sinus)
 Cranial part: Left internal jugular vein, connected to left brachiocephalic vein

75

Fate of Right anterior cardinal vein?

 Cranial part: Right internal jugular vein
 Caudal part: right brachiocephalic vein, SVC

76

Fate of Medial anastomosis (anterior cardinal veins)?

Left brachiocephalic vein

77

Fate of Left posterior cardinal vein + interconnecting
anastomosis?

 Left common iliac vein
 Sacral segment of IVC

78

Fate of Right posterior cardinal vein + interconnecting
anastomosis?

 Right common iliac vein
 Sacral segment of IVC

79

Fate of Left subcardinal vein + anastomotic channels?

 Left renal and gonadal vein

80

Fate of Right subcardinal vein ?

 Right renal and gonadal vein
 Renal segment of IVC

81

Fate of Left supracardinal vein?

 Left superior Intercostal vein + intercostal veins
 Hemizygous vein

82

Fate of Right supracardinal vein ?

 Intercostals
 Azygous vein (form with portion of posterior cardinal vein)
 3rd segment of IVC

83

Fate of left sacrocardinal vein?

Obliterated

84

What causes double IVC defect?

left sacrocardinal vein fails to disconnect with left subcardinal vein (develops into Left renal and gonadal vein) >
persistent left sarcocardinal vein

Normally right sacrocardinal vein forms hepatic segment of IVC

85

Results of double IVC defect?

 Left common iliac vein may or may not be present
 Left gonadal vein remains as normal
 Does not affect other organs

86

Cause of Absence of IVC?

right subcardinal vein (develops into renal segment of IVC normally) fails to connect with liver >

shunts blood directly into
right supracardinal vein (connects with azygous vein)

87

What causes Left SVC defect?

 Left anterior cardinal vein persists; and
 Common cardinal vein and proximal part of
right anterior cardinal veins obliterate (normally persist to form internal jugular vein and portion of SVC)

88

Result of Left SVC defect?

 Right brachiocephalic vein channels blood
flow from right to left
 Left SVC drains into right atrium through coronary sinus

89

Cause of Double SVC defect?

 Left anterior cardinal vein persists (normally middle segment obliterated, cranial end= internal jugular, caudal end= left superior intercostal vein, Distal end > coronary sinus)
 Left brachiocephalic vein fails to form (no anastomosis of anterior cardinal veins)

90

Result of Double SVC defect?

left SVC drains into right atrium through coronary sinus

91

5 locations in fetal circulation that allow oxygenated blood from placenta to mix with desaturated blood?

1) Ductus venosus in portal
 Sphincter controls blood
pressure flowing from liver
to IVC

2) IVC (from lower extremities)

3) Head, limbs

4) Lungs

5) Ductus arteriosus (allow bypass of lungs to descending aorta)

92

Sequence of blood flow in fetal circulation? strating at umbilical vein at placenta.

Umbilical vein > Ductus Venosus in Liver > Inferior VC > RA > either RV or oval foramen to LA > RV to ductus arteriosus (or pulmonary vein) to descending aorta OR LA to LV to Aortic arch > Descending aorta > Umbilical arteries > placenta

93

Fate of umbilical arteries after birth?

Umbilical arteries close,
nonfunctional:
 Proximal portion becomes
superior vesical arteries
 Distal parts form medial
umbilical ligament

94

Fate of umbilical vein?

Umbilical vein closes >
become ligamentum teres
hepatis

95

Fate of ductus arteriosus at birth?

Ductus arteriosus closes to
become ligamentum
arteriosum (no need to bypass lungs to descending aorta)

96

Fate of Oval foremen at birth?

Oval foremen close due to high pressure of blood in left atrium > septate atrium

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