15 Development of the heart, fetal circulation

Question 1

Development of the heart includes:

Answer 1

• formation of the heart tube
• looping and further differentiation of the heart tube,
• partitioning of the heart – complete isolation of the leftand right halves
• formation of the valves.

Question 2

Early development of the heart: appearance of the heart tube

____ appears on the 18^th-19^th days (the end of the third week).

Answer 2

Heart primordium

Question 3

Early development of the heart: appearance of the heart tube

____ appears on the 18^th-19^th days (the end of the third week).

Answer 3

Heart primordium

Question 4

Early development of the heart: appearance of the heart tube

Heart primordium appears on the 18^th-19^th days (the end of the third week).

At this stage the embryo is a flat, trilaminar disc and the differentiation of the three germ layers has just begun.

→ Heart develops from the _____, a part of the intraembryonic mesoderm anterior to the oropharyngeal membrane.

Answer 4

cardiogenic area

Question 5

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

In response to inductive and permissive signals emanating from the endoderm, ectoderm, and midlinemesoderm

→ cardiogenic precursors form ____ within the splanchnic mesoderm at the cranial end of the embryonic disc called the cardiac crescent, or primary heart field.

Answer 5

a cardiac primordium

Question 6

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

What is the primary heart field (PHF)?

Answer 6

a horseshoe-shaped region in the visceral layer of lateral plate mesoderm called the primary heart field (PHF)

Question 7

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

In response to inductive and permissive signals emanating from the endoderm, ectoderm, and midlinemesoderm

→ cardiogenic precursors form a cardiac primordium within the splanchnic mesoderm at the cranial end of the embryonic disc called ______

Answer 7

the cardiac crescent, or primary heart field.

Question 8

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

In response to inductive and permissive signals emanating from the endoderm, ectoderm, and midlinemesoderm

→ cardiogenic precursors form a cardiac primordium within____ at the cranial end of the embryonic disc called the cardiac crescent, or primary heart field.

Answer 8

the splanchnic mesoderm

Question 9

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

In response to signals from the underlying endoderm, a subpopulation of cells within the cardiac crescent form ___ through the process of vasculogenesis

Answer 9

a pair lateral endocardial tubes

Question 10

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

In response to signals from the underlying endoderm, a subpopulation of cells within the cardiac crescent form a pair lateral endocardial tubes through the process of ___

Answer 10

vasculogenesis

Question 11

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

In response to signals from ____, a subpopulation of cells within the cardiac crescent form a pair lateral endocardial tubes through the process of vasculogenesis

Answer 11

the underlying endoderm

Question 12

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

The cardiac cresent, primary heart field PHF) develops in the splanchnopleura at ___ (which position of the embryo?)

Answer 12

the cranial end of the embryo.

Question 13

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

The cardiac cresent, primary heart field PHF) develops in____ at the cranial end of the embryo.

Answer 13

the splanchnopleura

Question 14

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

By ____, an endothelial tube is formed on each side, surrounded by the mesoderm of the splanchnopleura.

Answer 14

fusing the primitive blood vessels (vasculogenesis)

Question 15

Paths of migration of mesoderm during gastrulation

The most cranially migrating of these cells form the cardiogenic mesoderm, which moves cranial to the future position of ____

Answer 15

the oropharyngeal membrane (oval structures).

Question 16

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

During folding of the embryo, the two endothelial tubes migrate toward the midline in the ventral-caudal direction and then converge at the midline to form____

Answer 16

the primitive heart tube.

Question 17

Structure of the vasculature at the beginning of the 4th embryonic week - Position of the heart tube

During folding of the embryo, _____ migrate toward the midline in the ventral-caudal direction and then converge at the midline to form the primitive heart tube.

Answer 17

the two endothelial tubes

Question 18

How is the cardiac present formed?

Answer 18

The cardiac crescent is formed by the cranially bilateral heart fields fusion at the midline (in mammals)

Question 19

Formation of the pericardium/cavities open inthe splanchic mesoderm

Around the cardiac crescent, the formation of the prospective ___ in the splanchnopleura also begins

Answer 19

pericardial cavity

Question 20

Formation of the pericardium/cavities open inthe splanchic mesoderm

Around the cardiac crescent, the formation of the prospective pericardial cavity in the splanchnopleura also begins

→ as shown in Figure B, cavities are formed in ____

Answer 20

the splanchic mesoderm

Question 21

Formation of the pericardium/cavities open inthe splanchic mesoderm

Around the cardiac crescent, the formation of the prospective pericardial cavity in the splanchnopleura also begins

→ as shown in Figure B, cavities are formed in the splanchic mesoderm

→ . Figure C shows in longitudinal section the relationship of the heart tube to other structures: in front of it is (1)____ and behind it is (2)_____

Answer 21

1. the septum transversum (the primordium of thediaphragm)
2. the oro (bucco) pharyngeal membrane.

Question 22

Further development of the heart is mainlydetermined by the folding of the embryo (4^thweek)

The folding includes 2 things which are ___

Answer 22

1) folding around transverse axes – this will explain, how the heart primordium moves from „above the head” into the chest occupying its final position.

2) folding around the longitudinal axis – this will mainly explain the fusion of the structures originally developing on the two sides of the embryo.

Question 23

What happen to the heart primordial during Folding around transverse axes, Cranio-caudal folding?

Answer 23

The heart primordium, originally located in front of the oropharyngeal membrane, bends to its final thoracic position

Question 24

Folding around the longitudinal axis, lateral folding of the heart

Folding of the embryo results in _____ in the midline.

Answer 24

the fusion of the two endocardial tubes

Question 25

**Folding around the longitudinal axis, lateral folding of the heart** Folding of the embryo results in the fusion of the two **endocardial tubes** in the midline. Somewhat later ____ also unite and surround the endocardial tube.

Answer 25

the **myoepicardial mantles**

Question 26

**Folding around the longitudinal axis, lateral folding of the heart** Folding of the embryo results in the fusion of the two **endocardial tubes** in the midline. Somewhat later the **myoepicardial mantles** also unite and surround the endocardial tube. → ____ fuse ventrally, and finally, the dorsal mesocardium disappears.

Answer 26

The intraembryonic coeloms

Question 27

**Folding around the longitudinal axis, lateral folding of the heart** Folding of the embryo results in the fusion of the two **endocardial tubes** in the midline. Somewhat later the **myoepicardial mantles** also unite and surround the endocardial tube. → The intraembryonic coeloms fuse ventrally, and finally,\_\_\_ disappears.

Answer 27

the dorsal mesocardium

Question 28

**Folding around the longitudinal axis, lateral folding of the heart** → identify

Answer 28

Question 29

**Pericardium as part of the intraembryonic coelome** → identify

Answer 29

Question 30

**The primitive heart tube** What is the position of the heart tube after fusion?

Answer 30

Caudal to the head region and ventral to the foregut.

Question 31

**The primitive heart tube** The fused primitive heart is lined with endothelium and differentiation of ___ begins.

Answer 31

myoblasts from the mesoderm also

Question 32

**3 Parts of the heart tube** **Myocardium** differentiates from ____ with cardiomyocytes

Answer 32

the splanchic mesoderm

Question 33

**3 Parts of the heart tube** **Myocardium** differentiates from the splanchic mesoderm with cardiomyocytes → These cells mainly secrete \_\_\_

Answer 33

The cardiac jelly (special ECM) (rich in hyaluronic acid)

Question 34

**3 Parts of the heart tube** **epicardium** **(visceral pericardium**) → Develops later from cells of the \_\_\_

Answer 34

secondary heart field, SHF

Question 35

**3 Parts of the heart tube** The SHF arises from cells that migrate through ____ and then reside in visceral mesoderm near the floor of the posterior part of the pharynx

Answer 35

the primitive streak

Question 36

**3 Parts of the heart tube** The SHF arises from cells that migrate through the primitive streak and then reside in ____ near the floor of the posterior part of the pharynx

Answer 36

visceral mesoderm

Question 37

**3 Parts of the heart tube** → Identify

Answer 37

Septum transversum

Question 38

What's happening here?

Answer 38

**The heart tube directs blood flow in thecaudocranial direction**

Question 39

**_Looping and further differentiation of the heart tube_** ## Footnote Between weeks 4 and 8, the primitive heart tube undergoes _____ that transforms its single lumen into the four chambers of the definitive heart → laying down the basis for the separation of pulmonary and systemic circulations at birth.

Answer 39

a process of looping, remodeling, realignment, and septation

Question 40

**_Looping and further differentiation of the heart tube_** ## Footnote Between weeks 4 and 8, the primitive heart tube undergoes a process of looping, remodeling, realignment, and septation → The role of this process? → laying down the basis for the separation of pulmonary and systemic circulations at birth.

Answer 40

that transforms its single lumen into the four chambers of the definitive heart → laying down the basis for the separation of pulmonary and systemic circulations at birth

Question 41

**_Looping and further differentiation of the heart tube_** ## Footnote What is cardiac looping?

Answer 41

This process causes the heart to fold on itself and assume its normal position in the left part of the thorax with the atria posteriorly and the ventricles in a more anterior position.

Question 42

**Separation of pericardial cavity** Septum formation in the heart in part arises from development of endocardial cushion tissue in ____ and \_\_\_\_

Answer 42

the atrioventricular canal (atrioventricular cushions) and in the conotruncal region (conotruncal swellings)

Question 43

**Separation of pericardial cavity** Septum formation in the heart in part arises from development of ____ in the atrioventricular canal (atrioventricular cushions) and in the conotruncal region (conotruncal swellings)

Answer 43

endocardial cushion tissue

Question 44

**Separation of pericardial cavity** \_\_\_\_ in part arises from development of endocardial cushion tissue in the atrioventricular canal (atrioventricular cushions) and in the conotruncal region (conotruncal swellings)

Answer 44

Septum formation in the heart

Question 45

**Mesocardium dorsale** ## Footnote The heart tube initially remains connected to the posterior body wall through \_\_\_\_

Answer 45

Dorsal mesocardium

Question 46

**Mesocardium dorsale** ## Footnote The heart tube initially remains connected to the posterior body wall through the mesocardium dorsale. → Over time, cavities form in \_\_\_\_, resulting in the formation of pericardial sinuses.

Answer 46

the dorsal mesocardium

Question 47

**Mesocardium dorsale** ## Footnote The heart tube initially remains connected to the posterior body wall through the mesocardium dorsale. → Over time, cavities form in the dorsal mesocardium, resulting in \_\_\_\_

Answer 47

the formation of pericardial sinuses.

Question 48

**Formation of pericardial sinuses** Which structure will disappear during this process?

Answer 48

Mesocardium dorsale - disappears quickly

Question 49

**Formation of pericardial sinuses** Mesocardium dorsale - disappears quickly → Causing Two inflection points at the arterial and venous ends of the heart With the formation of an S-shaped curvature, the pericardial cavity closes into a channel between the two orifices → This channel is called?

Answer 49

the **_sinus transversus_**

Question 50

**Formation of pericardial sinuses** The visceral layer of the pericardium holds the arteries and veins together → then create an originally a common bending point which is called \_\_\_

Answer 50

**_sinus obliquus_**

Question 51

**Formation of pericardial sinuses** \_\_\_\_ holds the arteries and veins together → then create an originally a common bending point which is called **_sinus obliquus_**

Answer 51

The visceral layer of the pericardium

Question 52

**Formation of pericardial sinuses** The visceral layer of the pericardium holds ___ and ___ together → then create an originally a common bending point which is called **_sinus obliquus_**

Answer 52

the arteries and veins

Question 53

**Parts of the developing heart tube 1.** As the heart tube lengthens, it develops a series of expansions and shallow sulci that subdivide it into \_\_\_\_\_

Answer 53

primordial heart chambers.

Question 54

**Parts of the developing heart tube 1.** As the heart tube lengthens, it develops a series of expansions and shallow sulci that subdivide it into primordial heart chambers. → Starting at the inflow end, these are _____ (6)

Answer 54

* **the left and right horns of the sinus venosus** * the **primitive atrium** * **the primitive ventricle** * the **bulbus cordis** * the **outflow tract (truncusarteriosus)**.

Question 55

**Parts of the developing heart tube 1.** As the heart tube lengthens, it develops a series of expansions and shallow sulci that subdivide it into primordial heart chambers. 1. The **bulbus cordis forms \_\_\_\_** 2. **The primitive ventricle** gives rise to \_\_\_\_

Answer 55

1. much of the right ventricle 2. the left ventricle.

Question 56

**Parts of the developing heart tube 1.** As the heart tube lengthens, it develops a series of expansions and shallow sulci that subdivide it into primordial heart chambers. **→ The outflow tract (the conotruncus) will form ___ and \_\_**

Answer 56

**the conus arteriosus and the truncus arteriosus**

Question 57

**Parts of the developing heart tube 1.** As the heart tube lengthens, it develops a series of expansions and shallow sulci that subdivide it into primordial heart chambers. **→ The outflow tract (the conotruncus) will form the conus arteriosus and the truncus arteriosus** **→** both of which split to **become \_\_\_-(4)**

Answer 57

1. **outflow regions of the two ventricles** 2. **the ascending aorta** 3. **pulmonary trunk**.

Question 58

**Parts of the developing heart tube 1.** → Identify

Answer 58

Question 59

**Parts of the developing heart tube 1.** → Identify

Answer 59

Question 60

**Circulatory system at the end of 4th week** **→ identify**

Answer 60

Question 61

**Vessels in the head region at 4th week** → Aortic arch systems begin at \_\_\_

Answer 61

6th week

Question 62

List **Vessels entering to sinus venosus**

Answer 62

1. vv. vitellinae 2. vv. umbilicales 3. vv. cardinales communes

Question 63

**The primitive heart tube lengthens at both ends, particularly the outflow (arterial) end,** **→ through the addition of \_\_\_**

Answer 63

**cardiac progenitors from** **secondary heart field** **mesoderm** (Cells from these region will form the conus cordis, truncus arterious and parts of the right ventricle)

Question 64

While myocardial cells within developing primitive heart tube continue to proliferate, there is a continued recruitment of cardiac progenitor cells from outside the original cardiac crescent at both (1)\_\_\_\_ and \_\_\_\_ → The source of these cells is referred to as (2)\_\_\_\_\_

Answer 64

1. the arterial (cranial) pole and venous (caudal) pole. 2. the secondary heart field.

Question 65

Do **Neural crest cells** participate in heart development?

Answer 65

Yes

Question 66

The heart tube grows rapidly and curves in an S-shape. Consequently, the originally caudal atria are at the same height as and behind \_\_\_\_

Answer 66

the cranial truncus arteriosus (sinus transversus!). (By the 28-30th day the heart had taken its external shape but itslumene was still uniform, undivided.)

Question 67

**Parts of the developing heart tube 3.** As a result of the uneven growth and rotation of the heart * the atria become \_\_\_

Answer 67

dorsocranial → the right-left asymmetry increases.

Question 68

**Development of atria** Venous blood initially enters the sinus horns through \_\_\_\_\_

Answer 68

paired, symmetrical common cardinal veins.

Question 69

**Development of atria** Venous blood initially enters the sinus horns through paired, symmetrical common cardinal veins. → Changes in the venous system rapidly shift (1)\_\_\_\_ return to the right so that all blood from the body and umbilicus enters the future right atrium through (2)\_\_\_\_ and \_\_\_\_ The left sinus horn becomes the coronary sinus, which drains the myocardium.

Answer 69

1. the entire systemic venous 2. the developing superior and inferior venae cavae.

Question 70

**Development of atria** Venous blood initially enters the sinus horns through paired, symmetrical common cardinal veins. → Changes in the venous system rapidly shift the entire systemic venousreturn to the right so that all blood from the body and umbilicus enters the future right atrium through the developing superior and inferior venae cavae. → The left sinus horn becomes (1)\_\_\_\_\_, which drains (2)\_\_\_\_

Answer 70

1. the coronary sinus 2. the myocardium.

Question 71

**Development of atria** Venous blood initially enters the sinus horns through paired, symmetrical common cardinal veins. → Changes in the venous system rapidly shift the entire systemic venous return to the right so that all blood from ___ and ____ enters the future right atrium through the developing superior and inferior venae cavae. → The left sinus horn becomes the coronary sinus, which drains the myocardium.

Answer 71

the body and umbilicus

Question 72

**Development of atria** A process of _____ incorporates the right sinus horn and the ostia of the venae cavae into the posterior wall of the future right atrium, displacing the original right half of the primitive atrium.

Answer 72

**intussusception**

Question 73

**Development of atria** A process of **intussusception** incorporates ____ and ____ into the posterior wall of the future right atrium, displacing the original right half of the primitive atrium.

Answer 73

the right sinus horn and the ostia of the venae cavae

Question 74

**Development of atria** A process of **intussusception** incorporates the right sinus horn and the ostia of the venae cavae into \_\_\_\_\_, displacing the original right half of the primitive atrium.

Answer 74

the posterior wall of the future right atrium

Question 75

**Development of atria** A process of **intussusception** incorporates the right sinus horn and the ostia of the venae cavae into the posterior wall of the future right atrium, displacing\_\_\_

Answer 75

the original right half of the primitive atrium.

Question 76

**Development of atria** The pulmonary vein develops in the midline and then shifts to \_\_\_\_ → the trunk of the pulmonary vein is subsequently incorporated by (2)\_\_\_\_ to form most of the left atrium.

Answer 76

1. the future left atrium 2. intussusception

Question 77

**Development of atria** The pulmonary vein develops in the midline and then shifts to the future left atrium →\_\_\_\_\_ is subsequently incorporated by intussusception to form most of the left atrium.

Answer 77

the trunk of the pulmonary vein

Question 78

**Development of atria** The pulmonary vein develops in the midline and then shifts to the future left atrium → the trunk of the pulmonary vein is subsequently incorporated by intussusception to form\_\_\_\_

Answer 78

most of the left atrium.

Question 79

**Development of atria** Right and left venous valves: two semilunar structures at the sinu-atrial junction. → Postero-superiorly they unite and form \_\_\_\_\_

Answer 79

the **septum spurium**.

Question 80

**Development of atria** Right and left venous valves: two semilunar structures at the sinu-atrial junction. → Postero-superiorly they unite and form the **septum spurium**. → The left one later completly disappears by \_\_\_\_

Answer 80

fusing with the interatrial septum.

Question 81

**Development of atria** Right and left venous valves: two semilunar structures at the sinu-atrial junction. → Postero-superiorly they unite and form the **septum spurium**. → The left one latercompletly disappears by fusing with the interatrial septum. → The right one divides into two 1. the upper part persists as \_\_\_\_\_\_ 2. the lower gives ____ and \_\_\_

Answer 81

1. a part of the **crista terminalis** 2. the mass of the **Thebesian and the Eustachian valves.**

Question 82

**Development of atria** As they are all derived from the same structure, valves of IVC and coronarysinus as well as the crista terminalis can be marked with one uninterrupted line! (for reading)

Answer 82

(for reading)

Question 83

**Partitioning of the heart 4th to 5th week** 1. Septation of \_\_\_\_\_ 2. Formation of \_\_\_\_\_\_ 3. Formation of \_\_\_\_ 4. Appearance of the membranous interventricular septum and the spiral aorticopulmonary septum.

Answer 83

1. the common atrioventricular (AV) orifice. 2. the interatrial septum. 3. the muscular interventricular septum.

Question 84

**Partitioning of the heart 4th to 5th week** 1. Septation of the common atrioventricular (AV) orifice. 2. Formation of the interatrial septum. 3. Formation of the muscular interventricular septum. 4. Appearance of ___ and \_\_\_\_\_

Answer 84

the membranous interventricular septum and the spiral aorticopulmonary septum.

Question 85

**Partitioning of the heart 4th to 5th week** 1. ____ of the common atrioventricular (AV) orifice. 2. ____ of the interatrial septum. 3. ____ of the muscular interventricular septum. 4. ____ of the membranous interventricular septum and the spiral aorticopulmonary septum.

Answer 85

1. Septation 2. Formation 3. Formation 4. Appearance

Question 86

**Septation of the common atrioventricular (AV) orifice** → What happen?

Answer 86

Endocardial cushions → Placed to the right

Question 87

**Formation of the interatrial septum** In the 5th and 6th weeks,\_\_\_\_\_, grow to separate the right and left atria. → These septa are perforated by a staggered pair of foramina that allow right-to-left shunting of blood throughout gestation.

Answer 87

a pair of septa, the **septum primum and the septum secundum**

Question 88

**Formation of the interatrial septum** In the 5th and 6th weeks, a pair of septa, the **septum primum and the septum secundum**, grow to \_\_\_ → These septa are perforated by a staggered pair of foramina that allow right-to-left shunting of blood throughout gestation.

Answer 88

separate the right and left atria.

Question 89

**Formation of the interatrial septum** In the 5th and 6th weeks, a pair of septa, the **septum primum and the septum secundum**, grow to separate the right and left atria. → These septa are perforated by a staggered pair of foramina that allow right-to-left shunting of blood throughout gestation. → What are the 2 foramina

Answer 89

**– foramen primum** **– foramen secundum**

Question 90

**Formation of the interatrial septum** In the 5th and 6th weeks, a pair of septa, the **septum primum and the septum secundum**, grow to separate the right and left atria. → These septa are perforated by a staggered pair of foramina that allow right-to-left shunting of blood throughout gestation. → What happen to foramina when the septum **primum** goes down?

Answer 90

– **foramen primum**, finally disappears – f**oramen secundum** (opens by apoptosis)

Question 91

**Formation of the interatrial septum** In the 5th and 6th weeks, a pair of septa, the **septum primum and the septum secundum**, grow to separate the right and left atria. → **Septum secundum will become \_\_\_\_**

Answer 91

**foramen ovale**

Question 92

**Formation of the interatrial septum** Two non-overlapping openings, valve-like septum primum: blood can only flow in ______ (direction?), according to the pressure gradient. After birth, the pressure in the left atrium increases, the plates merge

Answer 92

the left-right direction

Question 93

**Formation of the interatrial septum** Two non-overlapping openings, valve-like \_\_\_\_: blood can only flow in the left-right direction (direction?), according to the pressure gradient. After birth, the pressure in the left atrium increases, the plates merge

Answer 93

septum primum

Question 94

**The bulbus cordis expands to form \_\_\_\_\_, and during the 6th week a muscular ventricular septum partially separates the ventricles**

Answer 94

**the right ventricle**

Question 95

\_\_\_\_ expands to form the right ventricle, and during the 6th week a muscular ventricular septum partially separates the ventricles

Answer 95

**The bulbus cordis**

Question 96

**The bulbus cordis** expands to form the right ventricle, and during the 6th week a muscular ventricular septum partially separates the ventricles → What are the 2 parts of **septum interventriculare?**

Answer 96

1. **Muscular part** 2. **pars membranacea**

Question 97

**The bulbus cordis** expands to form the right ventricle, and during the 6th week a muscular ventricular septum partially separates the ventricles 2 parts of **septum interventriculare** → describe the muscular part?

Answer 97

a muscular septum growing from below that never reaches the AV orifice

Question 98

**The bulbus cordis** expands to form the right ventricle, and during the 6th week a muscular ventricular septum partially separates the ventricles 2 parts of **septum interventriculare** → describe the membranous part?

Answer 98

a septum separating the truncus arteriosus, which grows downwards and fuses with the pars muscularis.

Question 99

**Septum aorticopulmonale** During the 7th and 8th week, the outflow tract of the heart has completed the process of ___ (2)

Answer 99

septation and division

Question 100

**Septum aorticopulmonale** During the 7th and 8th week, the outflow tract of the heart has completed the process of septation and division → converting it into the separate, helically arranged outflow regions of\_\_\_\_ (4)

Answer 100

both ventricles and ascending aorta and pulmonary trunk.

Question 101

**Development of AV valves** The bicuspid (mitral) and tricuspid atrioventricular valves also develop from _____ tissue during the 5th and 6th weeks.

Answer 101

**atrioventricular cushion**

Question 102

**Development of AV valves** \_\_\_\_ and _____ (valves?) also develop from **atrioventricular cushion** tissue during the 5th and 6th weeks.

Answer 102

The bicuspid (mitral) and tricuspid atrioventricular valves

Question 103

**Development of AV valves** The bicuspid (mitral) and tricuspid atrioventricular valves also develop from **atrioventricular cushion** tissue during the 5th and 6th weeks. → Meanwhile, the heart undergoes \_\_\_

Answer 103

remodeling (that brings the future atria and ventricles into correct alignment with each other and also aligns both ventricles with their respective outflow vessels.)

Question 104

**Development of semilunar valves** During formation of \_\_\_\_\_, two smaller and shorter intercalated cushion tissues form in the opposite quadrants.

Answer 104

conotruncal septum

Question 105

**Development of semilunar valves** During formation of conotruncal septum, two smaller and shorter ____ form in the opposite quadrants.

Answer 105

intercalated cushion tissues

Question 106

**Development of semilunar valves** During formation of conotruncal septum, two smaller and shorter intercalated cushion tissues form in the opposite quadrants. In the most distal most conal segment, this new cushion tissue is exacavated and remodeled within _____ to form 2 cavities

Answer 106

the wall of each new vessel

Question 107

**Development of semilunar valves** During formation of conotruncal septum, two smaller and shorter intercalated cushion tissues form in the opposite quadrants. In the most distal most conal segment, this new cushion tissue is exacavated and remodeled within the wall of each new vessel to form 2 cavities → a similar cavity forms in both ___ and \_\_\_\_

Answer 107

the aortic and pulmonary sides of conotruncal septum.

Question 108

**Development of semilunar valves** During formation of conotruncal septum, two smaller and shorter intercalated cushion tissues form in the opposite quadrants. In the most distal most conal segment, this new cushion tissue is exacavated and remodeled within the wall of each new vessel to form 2 cavities → a similar cavity forms in both the aortic and pulmonary sides of conotruncal septum. → These cavities and the intervening tissue are subsequently remodeled to form ____ and \_\_\_\_

Answer 108

the valvular sinuses and semilunar valves