Gross Anatomy Cardiovascular Embryology

Front 1

when does the cardiovascular system begin to develop?

Back 1

week 3

mesenchymal cells derived from mesoderm form endothelial tubes which join to form primitive vascular system

Front 2

from what does the heart develop?

Back 2

splanchnic mesenchyme in cardiogenic area

Front 3

what forms the paired endocardial heart tubes?

Back 3

bilateral cardiogenic cords formed from mesenchyme, which become canalized and then fuse into a single heart tube

Front 4

what happens to the mesenchyme surrounding the cardiogenic cords?

Back 4

surrounding mesenchyme thickens to form myoepicardial mantle separated from endothelial heart tube by gelatinous cardiac jelly

Front 5

what are the four parts of the primitive heart?

Back 5

sinus venosus
atrium
ventricle
bulbus cordis

Front 6

what veins drain into the sinus venosus in the primitive heart?

Back 6

vitelline veins from the yolk sac
umbilical veins from the chorion
common cardinal veins from the embryo

Front 7

with what is the truncus arteriosus continuous caudally? cranially?

Back 7

caudally - bulbus cordis

cranially - enlarges to form aortic sac (from which aortic arches arise)

Front 8

what do the systems of paired veins become after birth?

Back 8

vitelline system - portal system
cardinal system - caval system
umbilical system - degenerates

Front 9

why does the bulboventricular loop form?

Back 9

bulbus cordis and ventricle grow faster than the rest of the heart and it bends on itself to form the bulboventricular loop

Front 10

what happens at the same time that the bulboventricular loop forms?

Back 10

heart invaginates into pericardial cavity

Front 11

what forms the transverse pericardial sinus?

Back 11

dorsal mesocardium (which attaches heart to dorsal wall of pericardial cavity) degenerates to form the transverse pericardial sinus

Front 12

when does the first heartbeat occur?

Back 12

21 to 22 days

Front 13

where do the peristalsis-like waves of the primordial heart begin?

Back 13

sinus venosus

Front 14

when does the heart have coordinated contractions which result in unidirectional flow?

Back 14

by the end of week 4

Front 15

what is the pathway through the primitive heart?

Back 15

blood enters the sinus venosus from vitelline, cardinal, and umbilical veins

blood flows into primitive ventricle

ventricular contraction pushes blood into the bulbus cordis and truncus arteriosus into the aortic sac, passing the aortic arches and branchial arches

blood passes to dorsal aortae for distribution to embryo, yolk sac and placenta

Front 16

when does the heart divide into four chambers?

Back 16

between weeks 4 and 7

Front 17

what divides the atrioventricular canal?

Back 17

endocardial cushions from the dorsal and ventral walls and begin approaching each other at week 5, fusing, and dividing the atrioventricular canal into right and left canals

Front 18

when does the septum primum begin to extend into the atrium? from where?

Back 18

day 28

superoposterior wall, growing caudally toward atrioventricular canal

Front 19

when are the left and right atria separated by the septum primum?

Back 19

fifth week

Front 20

what is the ostium primum?

Back 20

foramen that forms in the septum primum

Front 21

when does the septum primum fuse with the endocardial cushions to obliterate the ostium primum?

Back 21

at the end of the sixth week

Front 22

what is the ostium secundum?

Back 22

shunt formed by the coalescence of perforations in the septum primum, which form before the ostium primum closes

Front 23

what is the septum secundum?

Back 23

a flap growing from the roof of the right atrium, but not reaching the endocardial cushion, leaving an opening called the foramen ovale

Front 24

what are the two staggered openings through which blood shunting from right atrium to left atrium passes?

Back 24

foramen ovale (from septum secundum)

foramen secundum (septum primum)

Front 25

what closes the foramen ovale after birth?

Back 25

fusion of the septum primum with the septum secundum

Front 26

from where is the coronary sinus derived?

Back 26

left horn of the sinus venosus

Front 27

from where is the right atrium derived?

Back 27

smooth part (sinus venarum) - right horn of the sinus venosus

muscular part (auricle) - primitive atrium

Front 28

what separates the sinus venarum from the auricle internally and externally?

Back 28

internally - crista terminalis

externally - sulcus terminalis

Front 29

until when is the crescentic fold which partitions the ventricles open cranially (interventricular foramen)?

Back 29

until end of week 7

Front 30

when does the aorticopulmonary septum divide the truncus arteriosus into the pulmonary trunk and aorta?

Back 30

during week 5

valves develop from proliferation of subendocardial tissue

Front 31

from what temporary pacemaker does the sinus venosus take over?

Back 31

primitive atrium

Front 32

when does the sinoatrial node develop? from where?

Back 32

week 5
(part of the sinus venosus which becomes incorporated into the right atrium)

Front 33

from where does the atrioventricular node develop?

Back 33

sinus venosus

Front 34

when is the critical period of heart development?

Back 34

20-50 days after fertilization

Front 35

what is the most common defect of the cardiac septa?

Back 35

ventricular septal defects

Front 36

what is a membranous ventricular septal defect?

Back 36

oval membranous portion of interventricular septum fails to develop

Front 37

what is a muscular septal defect?

Back 37

perforation anywhere in the muscular part of the interventricular septum

caused by excessive resorption of myocardial tissue during formation of muscular part of interventricular septum

Front 38

what is cor triloculare biatriatum?

Back 38

3-chambered heart resulting from absence of interventricular septum

Front 39

what does tetralogy of fallot consist of?

Back 39

pulmonary valve stenosis
ventricular septal defect
overriding aorta
hypertrophy of right ventricle

(cyanosis is obvious sign but may not be present at birth)

Front 40

what is pulmonary valve stenosis?

Back 40

cusps of pulmonary valve are fused together to form a dome with a narrow central opening

Front 41

when do aortic arches, arising from the aortic sac, penetrate the branchial arches?

Back 41

week 4 and 5

(when the branchial arches form)

Front 42

when is the primitive aortic arch pattern transformed into the adult arterial arrangement?

Back 42

during week 6 to 8

Front 43

when does the lymphatic system begin to develop?

Back 43

week 5

Front 44

how does the lymphatic system develop?

Back 44

6 primary lymph sacs develop, and later become interconnected by lymph vessels

lymph nodules don't appear until just before and/or after birth

Front 45

what is a hygroma?

Back 45

tumor-like mass of dilated lymphatic vessels derived from pinched-off portion of jugular lymph sac

Front 46

via what vein does oxygenated blood return to the fetus from the placenta?

Back 46

umbilical vein

drains into liver or passes by via ductus venosus

Front 47

what forms a shunt for oxygenated blood to bypass the liver?

Back 47

ductus venosus

Front 48

what structures of the fetal heart close after birth?

Back 48

foramen ovale
ductus arteriosus
ductus venosus
umbilical vessels

Front 49

how long does it take for left ventricular wall to be thicker than right?

Back 49

1 month after birth

(at birth right ventricular wall is thicker)