9/1 Embryology of the heart

Question 1

what is the termonology of embriology that is different from med.

Answer 1

the cranial or superior is the anterior in embryo; the tail or caudal is posterior in embrio

Question 2

why do we care about cardio development?

Answer 2

most common birht defects. the leading cause of infant morality.

Question 3

what is one of the unique properites of circulation

Answer 3

it is always needed and the needs change constantly and must be adapted to the living being as it changes from a tube to two chamber to a four chamber

Question 4

how is vasculogeniss accomplished

Answer 4

this is accomplished through the molecules FGF2 and VEGF and comes from a blood island (starts with mesodermal cells

Question 5

how is angiogenesis accomplished

Answer 5

depends on VEGF and is the branching and elaboration of existing vesicles, and builds from what is already there.

Question 6

what are blood islands?

Answer 6

angiogenic cell clusters (should be vasculogenic) they are where vessels come from

Question 7

what is the significance of blood islands

Answer 7

they will give vessels and the heart

Question 8

where are the blood islands located

Answer 8

in the embryonic disc (spanchinic nesoderm) ; the chorionic somatic mesoderm.. ; conentinc stalk somatic mesoderm; yolk sac

Question 9

what is the layer of cells that contains the blood islands in a horse shoe shape?

Answer 9

the heart starts out as a horse shoe of blood islands near the top, and cranial to the head. this is the splanchinc mesoderm.

Question 10

Describe how the primordial heart gets to the thorax region:

Answer 10

head fold: bring the heart primordial to the thorax

Question 11

how do lateral body folds affect the heart development?

Answer 11

brings the paired heart primordia together at the midline where they fuse

Question 12

how do we get a cental tube of heart at the ventral midline

Answer 12

at 22 days the endocardial tube folds in and fuses to make the tube in the middle with the endocardial inside then the cardiac jelly, then the myocardium on the outside

Question 13

what are the layers of the heart?

Answer 13

endocardium; cardiac jelly; and the myocardium; epicardium;

Question 14

endocardium

Answer 14

inner most endothelial layer and continuous to the endothelial lining of the vasulature

Question 15

cardiac jelly

Answer 15

extrcellular matrix and gives rise to the valves

Question 16

myocardium

Answer 16

outer muscular layer.

Question 17

epicardium

Answer 17

outer most layer, derived from the cells that migrate in from the septum transversum and form the coronary arteriers, include the endothelial lining and smooth muscle.

Question 18

where is the gut located in a cross section of the embrio

Answer 18

below the notochord and above the heart

Question 19

where is the spanchnic mesoderm

Answer 19

it lines below the GI tract and arose from the lateral plate mesoderm that splits open to give the spanchnic mesoderm

Question 20

what will lead to the orientation of the heart?

Answer 20

cardiac looping which is coordinated with the left right orientation of the rest of the body.

Question 21

how does cardiac looping work?

Answer 21

the heart will make an s curve where the ventricle starts at the cranial and then twists around the antrium and will end in the caudle position.

Question 22

where does the heart fuse into one tube

Answer 22

ventral midline

Question 23

where do the antrium start in a sinble tube heart

Answer 23

the antrium starts at the bottom and then twists counterclockwise around to end up towards the top (this is looking ventral to the left, and dorsal to the right in a side-on view.

Question 24

describe the orientation of the primitive tube heart

Answer 24

the RA and LA in a branch at the bottom of the heart, then the LV in the middle bottom, and the RV in the middle and the Outflow at the top (called the CT).

Question 25

what happans at the end of looping

Answer 25

the Atrium is at the top and the ventral is at the bottom and there are only those two chambers.

Question 26

how does the primitive twisted tube heart start to separate into separate ventricles?

Answer 26

a cushion of cells starts to form in common atrioventricular canal. A superior endocardial cushion and an inferior one (small lateral cushions form as well). These cushions fuse together to form seperat right and left atrioventricular canals through the heart.

Question 27

how do we make the endocardial cushions?

Answer 27

the cells from the endothelium are induced by myocardium to migrate into the cardiac jelly

Question 28

what is the importance of the endocardial cushion

Answer 28

it will form the valves

Question 29

how are the left and right atrium separated in the primitive atrium?

Answer 29

the septum premium grows between the two, nearly occluding the ostium primum that forms (which would prevent the outflow of heart form the right atrium). as the ostium primum closes, programed cell death opens up the osmium secundum. as the secundum opens, the septum secundum grows and leaves a hole called the foramen ovale.

Question 30

why are the foramen ovale and the ostium secundum offset?

Answer 30

to provide a primitive check valve to prevent back flow to the right atrium! (the primum is flexible and the secundum is not)

Question 31

what is the froaman ovale

Answer 31

the second hole formed and it is formed in the septum secondum.

Question 32

what is the muscular ventricular septum.

Answer 32

the beginging of the division of the right and left ventricle form the bottom of the heart up (the division will be completed during outflow track septation)

Question 33

what forms the valves in the heart?

Answer 33

atrioventricular canals form valves through mesodermal proliferation in the myocardium. (the tissue under this build up then atrophies and you get thin flaps or valves.

Question 34

how do the neural crest cells contribute to the development of the heart

Answer 34

outflow track septation! therefore look for defects in outflow tract septation associated with defects in neural development.

Question 35

where do the neural crest cells come from to migrat to the heart

Answer 35

from the hind brane and arches 3,4,6

Question 36

why would a neural defect depentdent on the neural crest cells contribute to heart defects

Answer 36

the migration of neural crest cells to form the outflow septation.

Question 37

how do the two different paths out of the heart form?

Answer 37

from neural crest cell cushoins or ridges that from in a spiral on the single out flow tract and shunt blood from each ventricle into different paths.

Question 38

How do we devide the ventricle into two chambers?

Answer 38

by haveing the twisting ridges fuse together and fuse to the muscular ridge on the bottom of the heart. i.e. the conotruncal septa fuse with the interventricular septum!

Question 39

highlight the changes in blood flow after birth

Answer 39

the oval foramen closes immediately, as well as the ductus venosus, ductus arteriosis and placental vessels closing within minutes.

Question 40

Tricuspid Atresia

Answer 40

What: Atresia of tricuspid on right (no valve on right and very little atrium) closure of the oval foramen will shut down circulation (no where for the right atrium to go),

Question 41

Persistent Truncus Arteriosus

Answer 41

the ventricles don’t seperate because the outlow track fails to seperate out. No pulmonary semi-lunar valve. mixed blood to both the body and the lungs at the same time with every pump.

Question 42

Transposition of Great arteries

Answer 42

the aorta and the pulmonary artery go to the wrong ventricles. From a failure to spiral out the outflow seperation, ok before birth because of the ductus arteriosus to shunt blood to the right artery

Question 43

Pulmonary valvular atresia

Answer 43

no pulmonary semilunar valve, the right ventricle atrophies, tolerated before birth because of ductus arteriosus and the oval foramen to shunt blood to the left side and to the lungs.

Question 44

Tetralogy of Fallot

Answer 44

stenosis of the pulmonary trunk. interventricular septal defect, hypertrophy of the right ventricle. reduced function when the ductus arteriosus closes and can’t shunt blood to the lungs.