Anatomy- Cardiovascular System Embryology

Front 1

When does the cardiovasculature system begin to develop?

Back 1

during week 3

Front 2

Mesenchymal cells derived from mesoderm form what which join to form the primitive vascular system?

Back 2

endothelial tubes

Front 3

When does heart development occur?

Back 3

week 3

Front 4

What does the heart develop from and what area does this occur?

Back 4

1. splanchnic mesenchyme
2. cardiogenic area

Front 5

What are the bilateral cardiogenic cords formed from? What do the lilateral cardiogenic cords form?

Back 5

1. formed from mesenchyme
2. the cords develop a lumen and form the paired endocardial heart tubes

Front 6

What do the endocardial heart tubes eventually do?

Back 6

They fuse into a single heart tube known as the primitive heart

Front 7

The mesenchyme surrounding the endocardial heart tubes thickens to form what?

Back 7

myoepicardial mantle(future myocardium and epicardium)

Front 8

What separtaes the myoepicardial mantle from the endothelial heart tube?

Back 8

gelatinous cardiac jelly

Front 9

What does the myocardial mantle eventually become?

Back 9

1. myocardium (muscle layer)
2. epicardium (outer layer)

Front 10

What does the endothelial heart tube eventually become?

Back 10

endocardium (inner layer of heart)

Front 11

The future heart (developed from endothelial heart tube) develops dilatations and constrictions resulting in what 4 chambers?

Back 11

1. sinus venosus
2. atrium
3. ventricle
4. bulbus cordis

Front 12

What structure is continuous caudally with the bulbus cordis? This structure englarges to form what which is the precursor for what?

Back 12

1. truncus arteriosus
2. aortic sac
3. aortic arches

Front 13

What does the sinus venosus receive?

Back 13

1. umbilical veins from the chorion
2. vitelline veins from the yolk sac
3. common cardinal veins from the embryo

Front 14

What 3 systems of paired veins drain into the primitive heart?

Back 14

1. vitelline system
2. cardinal system
3. umbilical system

Front 15

What will the vitelline system of veins become?

Back 15

portal system

Front 16

What will the cardinal system of veins become?

Back 16

caval system

Front 17

What happens to the umbilical system of veins after birth?

Back 17

they degenerate after birth

Front 18

What two sections of the primitive heart grow faster causing the heart to bend upon itself? What does this bending form?

Back 18

1. bulbus cordis and ventricle grow fast
2. bulboventricular loop formed

Front 19

Where do the atrium and sinus venosus come to lie to the bulbus cordis, truncus arteriosus and ventricle upon formation of the bulboventricular loop?

Back 19

dorsally

Front 20

At the same time the bulboventricular loop is forming what does the heart do?

Back 20

invaginates into the pericardial cavity

Front 21

The dorsal mesocardium which attaches the heart to the dorsal wall of the pericardial cavity degenerates and forms what?

Back 21

transverse pericardial sinus

Front 22

The first heartbeat occurs on what days?

Back 22

21-22 days

Front 23

How does the first heartbeat form and from what area does it begin?

Back 23

1. originates in the muscle (myocardium) and forms peristalsis like waves
2. these waves begin in the sinus venosus

Front 24

What is the order of blood flow during the first heart beat?

Back 24

1. sinus venosus
2. atrium
3. ventricle
4. bulbus cordis
5. truncus arteriosus
6. aortic sac

Front 25

Coordinated contractions of the heart resulting in unidirectional flow happens by when?

Back 25

by the end of week 4

Front 26

By the end of week 4 what has happened in regards to cardiovascular development?

Back 26

coordinated contractions of the heart resulting in unidirectional flow of blood

Front 27

Describe the flow of blood through the primitive heart?

Back 27

1. blood enter sinus venosus from vitelline, cardinal, and umbilical veins
2. blood flows to primitive ventricle
3. upon ventricular contraction, blood flows into bulbus cordis and then truncus arteriosus and then the aortic sac, passing into the aortic arches and branchial arches
4. blood then passes into the dorsal aorta for distribution to the embryo, yolk sac, and placenta

Front 28

When does the heart divide into a 4 chambered heart?

Back 28

between weeks 4 and 7

Front 29

What happens between weeks 4 and 7 in relation to heart development?

Back 29

the heart divides into a 4 chambered heart

Front 30

What form on the dorsal and ventral walls of the atrioventricular canal?

Back 30

endocardial cushions

Front 31

When the endocardial cushions approach each other around week 5 what happens?

Back 31

1. they fuse which divides the atrioventricular canal into right and left canals

Front 32

At what week do the endocardial cushions fuse together to divide the right and left atrioventricular canals

Back 32

week 5

Front 33

What event starts on day 28 and continues to week 6?

Back 33

1. the septum primum begins to extend into the atrium from the superoposterior wall and grows caudally
2. by the sixth week it will fuse with the endocardial cushions completely separating the right and left atria

Front 34

What is the ostium primum (O1)? When does it completely disappear?

Back 34

It is the diminishing foramen between the atria which is diminished as the septum premium grows towards the endocardial cushions
2. it completely disappears when the septum premium completely fuses with the endocardial cushions at the end of week 6

Front 35

Before the ostium primum closes, what form near the superior edge of the septum primum and what do they combine to form?

Back 35

1. perforations form
2. they combine to form the ostium secundum

Front 36

What does the ostium secundum create?

Back 36

a shunt from the right atrium to the left atrium

Front 37

What structure grows from the roof of the right atrium shortly after the foramen secundum develops and how far does it grow?

Back 37

1. septum secundum grows from the roof of the right atrium and
2. doesn't reach the endocardial cushion

Front 38

What opening is formed since the septum secundum doesn't fuse with the endocardial cushions?

Back 38

foramen ovale

Front 39

The formaen ovale has a valve formed from degeneration of what?

Back 39

cranial portion of the septum primum

Front 40

Perforations formed in the superior edge of the septum primum are formed due to what happening to the cells?

Back 40

apoptosis

Front 41

The blood shunted from the right atrium to the left atrium passes through what 2 staggered openings and what structures are these opening associated with?

Back 41

1. foramen ovale - septum secundum
2. foramen (ostium) secundum- septum primum

Front 42

What does the foramen ovale allow before birth and what happens to it after birth?

Back 42

1. before birth- allows blood to pass from right atrium into the left atrium
2. after birth - closes by fusion of the septum primum and the septum secundum

Front 43

What prevents reflux in the foramen ovale before birth?

Back 43

prevented by the valve

Front 44

The sinus venosus develops a right and left horn which eventually become?

Back 44

1. left horn- coronary sinus
2. right horn- becomes incorporated into the right atrium

Front 45

The smooth part of the right atrium is what and is derived from what? The muscular part is what and what is it derived from?

Back 45

1. smooth part= sinus venarum (derived from sinus venosus)
2. muscular part = auricle (derived from primitive atrium)

Front 46

The sinus venarum and auricle of the right atrium are separated internally and externally by what?

Back 46

1. internally by crista terminalis
2. externally by the sulcus terminalis

Front 47

The left atrium has what structures partially incorporated into it?

Back 47

1. the primitive pulmonary vein and its 4 main branches

Front 48

The portion of the pulmonary veins derived originally from the left atrium retains what kind of appearance?

Back 48

trabeculated appearance

Front 49

The venticles become partitioned by what? How long does this partition remain open and what is the name of this opening?

Back 49

1. partitioned by a crescentic fold
2. open until the end of week 7
3. opening called the interventricular foramen

Front 50

The interventricular septa is formed by what two parts?

Back 50

1. central membranous part
2. a surrounding muscular part

Front 51

After the interventricular formamen closes what do each of the ventricles communicate with?

Back 51

1. right ventricle with the pulmonary trunk
2. left ventricle with the aorta

Front 52

The truncus arteriosus becomes divided by what during what time? What does this division form on each side?

Back 52

1. aorticopulmonary septum
2. during week 5
3. divides into pulmonary trunk and aorta

Front 53

What do the valves of the openings of the pulmonary trunk and aorta develop from?

Back 53

proliferation of the subendocardial tissue

Front 54

What first acts as a primitive pacemaker of the heart and what soon takes over?

Back 54

1. primitive atrium = temp. pacemaker
2. sinus venosus soon takes over

Front 55

When does the sinuatrial node develop and what is it part of?

Back 55

1. develops during week 5
2. part of the sinus venosus incorporated into the right atrium

Front 56

What does the atrioventricular node develop from?

Back 56

1. develops from cells in the wall of the sinus venosus along with cells from the atrioventricular canal region

Front 57

When is the critical period of heart development?

Back 57

from day 20 to day 50 after fertilization

Front 58

Which type of cardiac septa defect is the most common?

Back 58

ventricular septal defect

Front 59

Membranous ventricular septal defect is due to what happening?

Back 59

Due to the failure of the fusion of extensions of both:
1. subendocardial tissue growing from the right side
2. aorticopulmonary septum
3. muscular part of the interventricular septum

Front 60

Which ventricular septal defect is the most common?

Back 60

membranous

Front 61

What is the swiss cheese type of defect?

Back 61

ventricular septal defect Type 4

Front 62

What happens to cause the muscular ventricular septal defect?

Back 62

1. perforation may appear anywhere in the muscular part of the interventricular septum
2. thought to be caused by tissue resorption of myocardial tissue during formation of the muscular part of the interventricular septum

Front 63

What is a cor triloculare biatriatum and what causes it?

Back 63

1. 3 chambered heart
2. caused by absence of interventricular septum

Front 64

What does the tetralogy of fallot consist of?

Back 64

1. pulmonary valve stenosis
2. ventricular septal defect
3. overriding aorta
4. hypertrophy of right ventricle

Front 65

What is an obvious sign of tetralogy of fallot?

Back 65

cyanosis

Front 66

What happens to the cusps in a pulmonary valve stenosis?

Back 66

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

Front 67

What is arterial vessels are formed during week 4 and 5? What vessels penetrate them and where do they arise from?

Back 67

1. branchial arteries
2. penetrated by aortic arches
3. arise from aortic sac

Front 68

During what week is the primitive aortic arch pattern transformed into the adult arterial arrangement of carotid, subclavian, and pulmonary arteries?

Back 68

week 6-8

Front 69

During week 6-8 what happens with the primitive aortic arches?

Back 69

They are transformed into the adult arterial arrangement of carotid, subclavian, and pulmonary arteries.

Front 70

How many primitive aortic arches are there?

Back 70

6 pairs (6 on each side)

Front 71

When does the lymphatic system begin to develop?

Back 71

around week 5

Front 72

What part of the lymphatic system is developed first and then what happens?

Back 72

6 primary lymph sacs develop and then later become connected by lymph vessels

Front 73

When do lymph nodules appear?

Back 73

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

Front 74

What is a hygroma?

Back 74

tumor-like mass of dilated lymphatic vessels derived from pinched off portion of jugular lymph sac
(present as a large bulge on or near neck)

Front 75

How does oxygenated blood return from the placenta?

Back 75

by the umbilical vein

Front 76

What happens to the blood brought back to the body from the umbilical vein?

Back 76

1. 1/2 goes through the liver
2. 1/2 bypasses the liver by the ductus venosus

Front 77

What vessel allows blood to bypass the liver in the fetus?

Back 77

ductus venosus

Front 78

Where does blood enter the right atrium from?

Back 78

enters via the inferior vena cava

Front 79

Describe the blood in a fetal right atrium?

Back 79

partially deoxygenated blood since now mixing with returning blood from the lower portion of the body and abdominal organs

Front 80

Most of the blood in the right atrium passes through what and into where in fetal circulation?

Back 80

1. passes through the foramen ovale
2. enters left atrium and mixes with deoxygenated blood returning from the lungs

Front 81

Where does blood flow once is reaches the left atrium? What does this mean for arteries to the heart, head, neck, and upper limbs?

Back 81

1. blood flows from the left atrium to the left ventricle and then out the ascending aorta
2. this means arteries running to the head, neck, heart, and upper limb are receiving well oxygenated blood

Front 82

A small amount of blood in the right atrium mixes with blood from the superior vena cava and coronary sinus. This blood travels to what structures and what two pathways can it take from there?

Back 82

1. some blood will go from the right atrium into the right ventricle. this blood leaves via the pulmonary trunk.
2. from here most of the blood passes into the ductus arteriosus and then into the aorta. some of the blood passes into the lungs via the pulmonary arteries

Front 83

What percentage of blood passes via the umbilical arteries into the placenta for reoxygenation? What does the rest do?

Back 83

1. 50%
2. the rest supplies the viscera and the inferior 1/2 of the body

Front 84

What is the coronary sinus?

Back 84

the vein that drains the tissues of the heart

Front 85

What parts of the fetal circulation are no longer needed after birth and close?

Back 85

1. foramen ovale
2. ductus arteriosus
3. ductus venosus
4. umbilical vessels

Front 86

Which ventricular walls are thicker before birth and which are thicked by the end of month 1 after birth?

Back 86

1. right ventricular walls before birth
2. left ventricular walls 1 month post birth

Front 87

What is the fetal circulation designed to do?

Back 87

To carry oxygenated blood from the placenta to the fetal circulation by bypassing the lungs

Front 88

When do changes that result in normal adult circulation occur?

Back 88

during infancy

Front 89

What are common defects in the development of adult circulation?

Back 89

1. patent foramen ovale
2. patent ductus arteriosus