Lecture 19: The Heart

Question 1

where is cardiogenic mesoderm located

Answer 1

cranially to oropharyngeal membrane

Question 2

what eventually engulfs the heart

Answer 2

pericardial coelom

Question 3

what forms the initial artery/vein system

Answer 3

blood islands coalescing

Question 4

where do vitelline arteries and veins empty

Answer 4

caudal end of heart tube

Question 5

how is blood initially pumped to the body

Answer 5

through a single tube

Question 6

what comprises the primitive heart tube

Answer 6

1) aortic sac
2) truncus arteriosis
3) bulbus cordis
4) primitive ventricle
5) primitive atrium
6) sinus venosus

Question 7

formation of the AV septum

Answer 7

dorsal AV cushion and ventral AV cushion approach each other

Question 8

what doe the AV septum partition

Answer 8

the AV canal into the R AV canal and L AV canal

Question 9

formation of the IV septum

Answer 9

muscular IV septum develops in midline on floor of ventricle (from cardiac mesoderm) and grows toward fused AV cushion
Membranous IV semptum from bulbar ridge and AV cushions also grows

Question 10

difference in initial vs end IV septum

Answer 10

initially, foramen in free edge of muscular IV septum and fused AV cushions. Then it gets closed by the membranous septum

Question 11

2 things that divide primitive atrium

Answer 11

septum primum and septum secundum

Question 12

what does septum primum come from

Answer 12

forms in roof of primitive atrium and grows toward AV cushions in AV canal

Question 13

what does the foramen secundum come from

Answer 13

forms in center of septum primumm, fenestrations that become one big hole

Question 14

when does the foramen primum start and end

Answer 14

forms between free edges of septum primum and AV cushions, closes when there is fusion with cushions

Question 15

where does the septum secundum form

Answer 15

the right of septum primum

Question 16

what is the foramen ovale

Answer 16

opening between the upper and lower limbs of the septum secundum

Question 17

how does blood get shunted in the embryonic heart

Answer 17

RA to LA via foramen ovale

Question 18

how is functional closure of foramen ovale achieved

Answer 18

decrease in right atrial pressure (from occlusion of placental circulation) and increase in left atrial pressure (due to pulmonary venous return)
*eventually septum primum and secudum will anatomically fuse

Question 19

what is the valve of the foramen ovale derived from

Answer 19

septum primum

Question 20

why is the foramen ovale significant

Answer 20

allows blood to bypass the fetal lungs

Question 21

path of aorta vs pulmonary artery

Answer 21

aorta: L ventricular outflow

pulmonary artery: R ventricular outflow tract

Question 22

what are the conotruncal ridges

Answer 22

bulbar and truncal ridges

Question 23

bulbar and truncal ridges

Answer 23

conotruncal ridges

Question 24

where do conotruncal ridges form

Answer 24

truncus arteriosis and bulbus cordis

Question 25

how does the aorticopulmonary septum form

Answer 25

neural crest cells from hindbrain through ph. arches 3,4,6 invade truncal and bulbar ridges - they grow and twist around each other and fuse to form AP septum

Question 26

what does the AP septum divide

Answer 26

truncus arteriosis and bulbus cordis into the aorta and pulmonary trunk

Question 27

what does the AP septum meet

Answer 27

the IV septum

Question 28

which is more ventral between aorta and pulmonary trunk

Answer 28

pulmonary trunk

Question 29

what are the SL valves called

Answer 29

aortic, pulmonic

Question 30

how many swellings per valve

Answer 30

3 subendocardial

Question 31

what area of the heart do the seminlunar valves separate between

Answer 31

aorta and LV and pulmonary artery and RV

Question 32

what do the AV valves separate

Answer 32

the atrium and ventricles

Question 33

names and function of AV valves

Answer 33

tricupsid (RA to RV) | mitral (LA to LV)

Question 34

what do AV valves develop from

Answer 34

proliferation of tissue around endocardial cushions and AV canals

Question 35

formation of dorsal aorta

Answer 35

initially a pair of tubes that fuse to form a single dorsal aorta which connects with the aortic arch. aortic arch connect to aortic sac in primitive heart tube.

Question 36

what is each paired aortic arch associated with

Answer 36

a pharyngeal arch

Question 37

what do the aortic arches connect to

Answer 37

aortic sac

Question 38

how many aortic arches develop

Answer 38

6, NOT AT THE SAME TIME

Question 39

where does the arterial pattern develop from 6 pairs of arteries

Answer 39

head and neck

Question 40

development of arteries in main body

Answer 40

R and L dorsal aortae

Question 41

what is the ductus arteriosis

Answer 41

a shunt (doesnt shunt everything)

Question 42

what does the 1st aortic arch become

Answer 42

L and R = maxillary/external carotid artery

Question 43

what does the 2nd aortic arch become

Answer 43

L and R stapedial artery

Question 44

what does the 3rd aortic arch become

Answer 44

L and R common carotid/internal artery

Question 45

what does the 4th aortic arch become

Answer 45

L = part of aortic arch, R = proximal R subclavian artery

Question 46

what does the 5th aortic arch become

Answer 46

rudimentary aorta

Question 47

what does the 6th aortic arch become

Answer 47

``` L= L pulmonary + ductus arteriosus R = R pulmonary aorta ```

Question 48

where do the primitive cardiac veins drain

Answer 48

sinus venosus

Question 49

what are the 3 primitive veins

Answer 49

vitellin (drain yolk sac, low O2) umbilical (from placenta, high O2) Common cardinal (from body of embryo, low O2)

Question 50

what is the fate of the primitive veins

Answer 50

very complex and differs between people

Question 51

what vein dissapears

Answer 51

R umbilical

Question 52

what happens to L umbilical vein

Answer 52

umbilical vein within umbilical cord, becomes ductus venosus

Question 53

what is the superior vena cava a derivative of

Answer 53

R anterior and R common cardinal veins