Cardiac Development 1

Question 1

When do heart cells begin to appear

Answer 1

week 2

Question 2

when does vascular system start to form

Answer 2

week 3

Question 3

why do we need vascular system

Answer 3

to transport substance around the featus

Question 4

what happens in week 2

Answer 4

progenitor cells( eventual heart cells) lie in epiblast

Question 5

what happens in week 3

Answer 5

progenitor cellsmove through primitive streak into visceral layer of lateral plate of mesoderm
then organise into horse shoe shape to form heart vessels shape

Question 6

Lateral folding 1

Answer 6

endoderm near primary heart field secretes vascualr endothelial growth factor which helps differntiate angioblasts, cardiac myoblasts, haemocytobloasts

Question 7

lateral folding 2

Answer 7

differentiated heart cells form 2 endothelial- lined tubes surrounded by myoblasts called endocardial tubes

Question 8

lateral folding 3

Answer 8

pockets behind the endocardial tubes form which eventually become pericardial cavities

Question 9

lateral folding 4

Answer 9

the 2 endocardial tubes fold together to join while the GI tract is pushed posteriorly

Question 10

lateral folding 5

Answer 10

heart tube now sits in pericardial cavity attached to posterior wall by dorsal mesocardium

Question 11

lateral folding 6

Answer 11

myocardial cells secrete extracellular matrix to separate mycocardium and endothelium

Question 12

craniocaudal folding 1

Answer 12

initially heart is sitting cranially but as craniocaudal folding occurs it is pulled caudally

Question 13

craniocaudal folding 2/3

Answer 13

when heart tube pulled down it goes into pericardial cavity
surrounding mesoderm forms secondary heart tube

Question 14

in heart tube where do endocardium, myocardium and epicardium come from

Answer 14

endothelial cell layer
myoblastssurrounding mesothelial cells

Question 15

how and when is heart tube formed

Answer 15

between day 20 and 22
left and right endocardial tubes move towards each other and fuse to form the heart tube

Question 16

these parts of heart tube become:
truncus arteriosus
Bulbus cordis
primitive ventricle
primitive atrium
sinus venous

Answer 16

Pulmonary trunk
right ventricle and pulmonary veins
left ventricle
both atria
S/I vena cava, conorary sinus

Question 17

when does cardiac loop begin and end

Answer 17

day 23 and 28

Question 18

when and where do septae develop

Answer 18

between day 27 and 37
seperate atria and ventricles, left and right atria and ventricles and outflow tract

Question 19

how does AV canal septum form

Answer 19

anterior and posterior endocardial cushions form and grow towards each other to form septum intermedium

Question 20

how does interventricular septum form

Answer 20

one septum grows up from heart apex
another grows down from septum intermedium
they grow towards eachother and fuse to form interventricular septum

Question 21

how does atrial septum form

Answer 21

septum primum grows down towards septum intermedium but does reach it leaving a hole called ostium primum
septum primum eventually closes stium primum
another hole is created in upper part of septum primum called ostium secundum
second septum called septum secundum forms
hole forms in sectum secundum called foramen ovale which closes at birth and become fossa ovalis