B4.046 - Cardiovascular Embryology Prework 2

Question 1

when does atrial septation happen

Answer 1

weeks 4-7

Question 2

when does ventricular septation happen

Answer 2

weeks 4-7

Question 3

identify what each of these structures turns into

Answer 3

orange - pulm. artery and aorta

dark orange - valves of aorta and pulm a.

red - right ventricle

pink - left ventricle

purple - both atria

Question 4

how does the endocardial cushion form

Answer 4

The myocardium deposits a unique extracellular matrix between the endocardium and itself

Endocardial cells in a certain region undergo an epithelial-to-mesenchymal transformation

Mesenchymal cells (migrating endocardial cushion cells) aid in formation of the atrioventricular canal

Question 5

what regio does endocardium derived cushion tissue form in

Answer 5

atrioventricular region and the outflow tract region

Question 6

the outflow tract region is also populated by what

Answer 6

invading neural crest cells

Question 7

fusion of opposing cushion tissues forms what

Answer 7

2 atrioventricular canals, and the outlets of both ventricles, the aorta and pulmonary trunk

Question 8

the conotruncal cushions contribute to what structure

Answer 8

membranous portion of the interventricular septum

Question 9

describe the heart at day 30

Answer 9

1. atrial pertitioning just beginning to happen
2. primary interventricular foramen undivided
3. outflow tract (bulbus cordis/truncus arteriosus) undivided
4. proximal portion of bulbus cordis becomes trabeculated and forms the right ventricle
5. atrioventricular canal undivided

Question 10

describe the septum primum

Answer 10

grows down from common atrium roof towards the endocardial cushions in the atrioventricular canal

Question 11

what is the formaen (ostium) primum

Answer 11

connects the right and left atrium

Question 12

identify the 2 structures pointed out here

Answer 12

top - foramen secundum

bottom - foramen premum

Question 13

what happens in the 5th week to the septum primum

Answer 13

programmed cell death creates new openings in the septum primum near the superior edge, called the foramen secundum

Question 14

what happens to the endocardial cushions in the 5th week

Answer 14

grow along septum primum and close foramen primum

Question 15

what happesn to the septum secundum in the 5th week of life

Answer 15

it forms to the right of teh septum primum

it grows down and fuses with an intermediate septum by the end of teh 6th week, but a foramen ovale persists throughout embryonic development

Question 16

what happens to the septum secundum in the 6th week of development

Answer 16

it grows down and fuses with an intermediate septum but a foramen ovale persists throughout embryonic development

Question 17

what is the function of the foramen ovale, in the septum secundum and foramen secundum in teh septum primum

Answer 17

it allows the blood to flow from right atrum to left atrium, but not left to right

Question 18

what happens in the 6th week of development

Answer 18

the septum primum meets and fuses with the septum intermedium

the foramen secundum is obliterated and the right and left atria are now separated.

Blood flows through the foramen ovale when its valve is open, but not when its closed

Question 19

during the 5th week of development what happens when the medial walls of the expanding ventricles become apposed

Answer 19

it formes the muscular interventricular septum

Question 20

what is the interventricular foramen

Answer 20

its the foramen between the muscular IV septum and the endocardial cushions, it remains open until about day 37

Question 21

what closes the IV foramen

Answer 21

the formation of the membranous portion of the IV septum, outgrowth of endocardial cushions towards muscular IV septum

Question 22

what cell type contributes to the membranous part of IV septum

Answer 22

neural crest cell derivatives

Question 23

outflow tract septation contribute to what on day 37

Answer 23

membranous IV septum

Question 24

when does formation of the atrioventricular valves happen

Answer 24

5th to 8th weeks

Question 25

what are conotrucal swellings or cushions

Answer 25

they form a spiral within the outflow of the beating heart while growing towards the aortic sac. On opposite walls they form the aorticopulmonary septum to divide the outflow of the heart into 2 spiraling channels, one for the aorta and one for the pulmonary trunk

Question 26

the lower portion of the AP septum contributes to what

Answer 26

upper (membranous) portion of the IV septum

Question 27

what do neural crest cells contribute to

Answer 27

the conotruncal ridges in truncus arteriosus (aslo membranous IV septum)

Question 28

what contributes to the formation of semilunar (aortic and pulmonart artery) valves

Answer 28

Outflow cushion with contribution from neural crest

Question 29

where are SA node cells originated from

Answer 29

caudal end of left heart tube, later sinus venosus, then right atrium

Question 30

where are AV node and bundle of His cells derived from

Answer 30

1. cells in teh left wall of the sinus venosus 2. cells from the atrioventricular canal

Question 31

when is circulation established

Answer 31

week 4

Question 32

what does arch 1 form in adults

Answer 32

part of maxillary arteirs (head)

Question 33

what does arch 2 form in adults

Answer 33

parts of hyoid and stapadial arteries (in neck and head)

Question 34

what does arch 3 form in adults \*\*

Answer 34

common and part of internal carotid artery (in neck) ## Footnote **External carotid forms from sprout off 3rd arch**

Question 35

what does arch 4 form in adults

Answer 35

right subclavian artery (R) and arch of the aorta (L)

Question 36

what does arch 5 form

Answer 36

Trick question!!! IT REGRESSES!!

Question 37

what does arch 6 form in adults

Answer 37

pulmonary arteries, ductus arteriosus

Question 38

what doe vitelline arties do

Answer 38

supply yolk sac; eventually fuse and form vessels to gut

Question 39

what do paired umbilical arteries form

Answer 39

(ventral branches of dorsal aortae) course to placenta

Question 40

describe coronary artery formation

Answer 40

Partially arise from epicardium following EMT (epithelial to mesenchymal transformation); mesenchymal cells contribute to endothelial and smooth muscle cells

Question 41

how do neural crest cells contribute to coronart arteries

Answer 41

contribute to smooth muscle cells along proximal segments of coronary arteries

Question 42

coronary arties grow into what structure

Answer 42

the aorta to establish blood flow to the heart muscle

Question 43

what do vitelline veins become

Answer 43

portal veinous system

Question 44

what does the umbillical vein do

Answer 44

carries blood from the placenta to the embryo

Question 45

what do the cardinal veins do

Answer 45

drain the body of the embryo; will form superior vena cava

Question 46

what to all veins drain to

Answer 46

sinus venosus

Question 47

while cardinal veins are initially bilateral, as they return blood to eh right and left horn of the sinus venosus portion of the heart what happens

Answer 47

venous system shifts to the right

Question 48

what happens to the right horn of the sinus venosus

Answer 48

becomes incorporated into the wall of the right atrium

Question 49

what happens to the left horn of the sinus venosus

Answer 49

becomes the coronary sinus (major venous drainage for blood that has perfused myocardium)