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Embryology TT > Cardiovascular development > Flashcards

Cardiovascular development Flashcards

1
Q

what is the cardiac crescent?

A

mesoderm migrates rostrally and laterally, forming the left and right heart fields either side of the primitive streak
migrate and join to form the cardiac crescent, become cardiac progenitor cells

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2
Q

what does the cardiac crescent create

A

first heart field, second heart field and head fold

receives signals from the overall ectoderm to make cardiac mesoderm

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3
Q

what do the first cardiac progenitor cells produce

A

angiogenic cell clusters coalesce to form endocardial tubes

forms basis for the heart chambers

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4
Q

what happens following the formation of the endocardial tubes

A

left and right tubes fuse at the midline with rostral folding
when fused, initially connected to foregut and endoderm then the connection breaks down

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5
Q

how do the endocardial tubes form from the cardiac crescent

A

vascular elements

formed through vasculogenesis, with vascular endothelial GF

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6
Q

what do the endocardial tubes give rise to

A

once fused, form the primitive heart tube surrounded by cardiac myocytes

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7
Q

tissues within the early heart tube

A

becomes endothelium surrounded by a mass of splanchnic mesoderm
cardiomyoctes progenitors invade the endocardial tube which will form myocardium

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8
Q

what is cardiac jelly?

A

thick layer of ECM surrounding the early heart tube

space in which cells can migrate into, will eventually form the epicardium

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9
Q

parts of primitive heart tube

A 
sinus venosus (base)
primitive atrium 
primitive ventricle 
bulbus cordis 
truncus arteriousus (top)
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10
Q

sinus venosus forms

A

L/R sinus horns, atria

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11
Q

primitive atrium forms

A

L ventricle, separated by AV sulcus

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12
Q

bulbus cordis forms

A

mostly RV

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13
Q

outflow tract forms

A

aorta and PA

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14
Q

attachment of the primitive heart tube

A

originally suspended int he cavity by the dorsal mesocardium, then ruptures allowing the heart to grow and change shape

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15
Q

when does contractile activity begin

A

before linear heart tube formation

day 18, calcium waves visible before striations

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16
Q

venous drainage of linear heart tube

A

3 pairs of vessels on the left and right sides of the embryo, all drain into the sinus venosus
vitelline veins drain yolk sac
cardinal veins drain body
umbilical veins drain placetna

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17
Q

cells of linear heart tube

A

initially just endothelial, then surrounded by mesoderm = myocardium, secrete ECM
separates myocardium from endocardium
rich in hyaluronic acid and proteoglycans
outer surface = epicardium

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18
Q

what is cardiac looping + day

A

day 23-28

4 presumptive chambers brought into correct spatial relationships

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19
Q

how does folding occur?

A

folding is an intrinsic property of heart tubes

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20
Q

how does looping affect blood flow

A

change in blood flow through the heart, first morphological sign of L/R assywmety in embryo

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21
Q

how does the heart shape change

A

rapid proliferation of cells at different rates

elongate and bend into C shape, then S

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22
Q

movement of different regions

A

bulbus cords = caudal, ventral, right (for RV)
primitive ventricle = left (for LV)
primitive atrium = dorsal and cranial
truncus arteriosus remains cranial (with conus cordis from bulbus) to form outflow tract

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23
Q

movement of blood vessels with looping

A

cranial ends of dorsal aorta pulled ventrally, form first aortic arch and then form 4 more
dorsal aortae fuse to form a single midline dorsal aorta
venous system redevelops, all blood enters the sinus horn via the superior and inferior venae cavae

24
Q

what occurs in separation

A

week 4-7
separation of common atria and ventricles
division off the outflow tract

25
Q

why do endocardial cushions form

A

ECM secreted between the endo and mesocardium, so endocardium balloons into the tube
some endocardial cells undergo EMT so become mesenchymal masses
also invaded by neural crest

26
Q

where do the cushions form

A

grow into the common AV canal
superior and inferior cushions grow and by 5the week ha er fused leaving 2 separate AV canals
lateral cushions also form

27
Q

first stage of atrial septation

A

crescent shaped septum primum grows down from the roof of the common atrium and extends towards cushions
as it grows, space behind is the ostium primum

28
Q

what occurs when the septum primum fuses with cushions

A

cells in septum die, forming holes within the body of the septum that fuse into a single opening = ostium secondum
(ostium primum closes)

29
Q

what follows the septum primum

A

the thick, muscular septum secondum grows down on the right side of the septum primum
doesn’t fuse with cushions
space behind septum = foramen ovale

30
Q

what does the foramen ovale form

A

foramen ovale and ostium secondum form a shunt between the atria
two openings don’t line up directly, so septum second acts as a valve (can be pushed by force of blood and then collapses back)

31
Q

what does the foramen ovale form in the adult

A

fossa ovalis in the right atrium

32
Q

how does ventricular septation begin

A

inter-ventricular septum grows up from the base of the heart, towards endocardial cushions

33
Q

important forces acting on ventricles

A

haemodynamic forces play a significant impact on sculpting

34
Q

tissue of septum

A

base = muscular, upper region where it joins cushions is membranous

35
Q

where does the IV septum fuse

A

doesn’t fuse with cushions, closes by fusion between the membranous IV septum and septum in outflow tract

36
Q

what is IV separation continuous with

A

outflow tract septation

37
Q

action of haemodynamic flows on outflow tract

A

create 2 spiralling blood streams, act on cardiac jelly rich wall of outflow tract
pressure causes formation of spiral conotruncal ridges that fuse together, dividing outflow tract

38
Q

shape of vessels as they emerge

A

aortic and pulmonary outflow twist around eachother as they emerge
conotruncal ridges fuse with IV septum and form membranous IV septum
neural crest cells essential

39
Q

septation defects

A

both ventricular and atrial occur, ventricular most common in membranous region
ventricular septal defects cause reduced CO, hypertrophy, increase pressure in pulmonary system

40
Q

defect where no septation of outflow occurs

A

persistent trunks arteriosus

41
Q

defect with no spiralling of vessels

A

transposition of the great vessels

42
Q

tetralogy of fallot

A

abnormal blood flow causes problems with septation of the outflow tract
extreme abnormality, get wrong alignment of ventricular and outflow septation so they don’t fuse in the middle
4 symptoms: pulmonary stenosis, IV septal defect, over-riding aorta, RV hypertrophy

43
Q

how do valves form

A

endocardial cells migrate into jelly
ventricular layer is hollowed out and thinned by cell death to form valve leaflets
spaces left by dead cells = chordae tendinae

44
Q

original arteries in body

A

vitelline supplies yolk sac

umbilical arteries supply placenta

45
Q

what are the aortic arches

A

forms future aortic and pulmonary trunks

5 pairs of aortic arches, not all present at once (I,II,III,IV,VI) - NO 5

46
Q

what occurs with arterial remodelling

A

generate the major vessels that leave the heart

47
Q

what do arch I and II form

A

regress quickly

48
Q

what does arch III form

A

carotid arteries

49
Q

what does arch IV and VI form

A

aortic arch and pulmonary trunk

connection between = ductus arteriosus, associated with vagus nerve

50
Q

changes at birth

A
  • lungs inflate, vascular resistance drops, blood goes through pulmonary circulation and return to LA increases
  • umbilical artery contract, blood flow from placenta stops
  • umbilical vein closes slowly, blood returns to infant
  • less blood in RA, more in LA so foramen ovale closes
  • ductus venosus closes -> ligamentum venosum
  • ductus arteriosus closes -> ligamentum arteriosum
51
Q

major pairs of veins in the embryo

A 
vitelline = drain yolk sac
umbilical = drain blood from umbilical cord into embryo
cardinal = draining of embryo proper
52
Q

vitelline vein development

A

right and left
each one divided into distal, middle and proximal parts by the developing liver
proximal parts anastomose around the duodenum to form the portal vein
middle two parts of the veins = liver sinusoids
proximal part of left disappears
proximal part of right forms part of IVC

53
Q

umbilical vein development

A

right and left
right disappears
proximal part of left disappears
distal left carries blood from placenta to liver
direct communication between left UV and IVC (ductus venosus)

54
Q

cardinal vein development

A

anterior = drain cephalic part
posterior = drain rest
various other addition cardinal veins form for specific organs

55
Q

venous blood flow before sedation

A

bias of blood flowing into RA before septation

Embryology TT (5 decks)

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