Heart Development

Question 1

In what week does the heart form

Answer 1

Wk. 3

Question 2

In what week does circulation begin

Answer 2

Wk. 4

Question 3

What is the heart derived from

Answer 3

Splanchnic mesoderm and NC Cells

Question 4

Heart fields are what in origin

Answer 4

Splanchnic mesoderm

Question 5

Where do the primary heart fields develop and what do they develop into

Answer 5

Develop from the cranial end mesoderm of the primary streak

Develop into:
LA, RA, LV

Question 6

Where do secondary heart fields develop from and what do they develop into

Answer 6

Develop from the mesoderm of the pharyngeal arches

Develop into:
RV, outflow tract, and part of the atria

Question 7

The three layers of the heart are derived from what

Answer 7

Splanchnic mesoderm

Question 8

What is mesentary

Answer 8

A double layer of splanchnic mesoderm

Question 9

In utero, the heart is suspended by what?

Answer 9

Dorsal mesoderm which becomes part of the posterior wall

Question 10

What forms the truncus arteriosus and aorticopulmonary septa

Answer 10

Neural crest cells that originate in the myelechephalan and then migrate through pharyngeal arches 3 - 6

Question 11

What genes regulate cardiac NC cell migration and differentiation

Answer 11

Hox
Nf - 1
Pax - 3

Question 12

What do the truncus arteriosus and bulbus cordis do

Answer 12

Fuse together to form the aorta and the pulmonary trunk

Question 13

Angioblasts are what and are derived from what

Answer 13

Are cardiogenic cords and are derived from splanchnic mesoderm

Question 14

How do the bulbus cordis and ventricles behave

Answer 14

They separate and move in oposite directions

Question 15

What is normal heart folding

Answer 15

R folding

Question 16

How is the atrioventricular canal formed

Answer 16

Endocardial cushions move together and form L and R AV canals which also separate atria from ventricles

Question 17

What are the endocardial cushions formed from

Answer 17

Mesodermal growth from the dorsal and ventral walls

Question 18

What can produces AV canal defects

Answer 18

Disruption of retinoid signaling

Question 19

What does the pectinate muscle come from

Answer 19

Primordial heart tube

Question 20

What does the cardiac smooth muscle come from

Answer 20

Sinus venosus from the R sinus horn

Question 21

What does the sinus venosus come from

Answer 21

The R sinus horn

Question 22

What does the right horn of the sinus venosus give rise to

Answer 22

The sinus venarum - smooth part of the RA
Orifices of superior and inferior vena cave
Orifices of the coronary sinus

Question 23

What does the left horn of sinus venosus become

Answer 23

The coronary sinus

Question 24

The R sinuatrial valve of the sinus venosus gives rise to what

Answer 24

Cranial - crista terminalis

Caudal - valve of coronary sinus

Question 25

What is the sinus venosus

Answer 25

The first chamber that empties into the RA

Question 26

What does the septum primum and septum secundum meet with

Answer 26

The endocardial cushions

Question 27

Define the foramen primum

Answer 27

The first shunt of the septum primum Gone when fused with endocardial cushions

Question 28

Define the foramen secundum

Answer 28

Second foramen of the septum primum Formation ensures shunting between LA and RA

Question 29

Define the foramen ovale

Answer 29

Foramen of the septum secundum Closes when baby takes its first breaths

Question 30

What happens in regards to the septums when the baby takes its first few breaths

Answer 30

The septum primum and the septum secundum fuse together, forming the interatrial septum The foramen ovale also closes

Question 31

How does the interventricular septum form

Answer 31

Muscular portion extends to meet the endocardial cushions but can’t make it, so membranous part takes over and reaches it

Question 32

What is the interventricular septum formed from

Answer 32

Splanchinic mesoderm

Question 33

How does the membranous interventricular septum form

Answer 33

Right and left bulbar ridges fuse, thus creating the membranous part and extending the interventricular septum

Question 34

Defects in the interventricular septum result from what

Answer 34

A defect in the membranous part

Question 35

What are the left and right bulbar ridges formed from

Answer 35

NC Cells

Question 36

Define acyanotic cardiac abnormality

Answer 36

L to R shunt

Question 37

Define cyanotic cardiac abnormalities

Answer 37

R to L shunt

Question 38

Ductus arteriosus Classification: Why does it occur: Treatment: CLinical presentation:

Answer 38

Acyanotic PDA doesnt close due to PGE2 which is mediated by COX2 Treat with COX - 2 inhibitors Presents as poor eating, tachycardia, high pressure inlungs - capillary destruction

Question 39

# Define atrial septal defect Classification: | Why does it occur:

Answer 39

Acyanotic Occurs due to septums not closing at right time

Question 40

Define ositum secundum

Answer 40

A patent foramen ovale with a patent foramen secundum (mismatched and do not fuse shut) Caused by excessive cell death and reabsorption of septum primum

Question 41

Define ositum primum

Answer 41

Septum primum (foramen primum) does not fuse with endocardial cushion This is also associated with a mitral valve cleft

Question 42

# Define VSD Classification: Why does it occur: CLinical presentation:

Answer 42

Acyanotic Membranous part of IVS does not form due to NC Cells The bulbus ridge did not fuse with the endocardial cushion

Question 43

Define complete AV septal defect

Answer 43

Primum ASD (ositis primum) that is contiguous with a VSD and a common AV valve

Question 44

Define partial AV septal defect

Answer 44

Primum ASD (ositis primum) a single AV annulus with 2 separate valve orifieces

Question 45

What is the embryological basis for AV septal defect and who does it mostly affect

Answer 45

Failure of endocardial cushions to fuse Mostly affects people with Downs

Question 46

# Define corrected transposition of the great vessels Embryological basis? Type?

Answer 46

The RA sends blood to the LV and the LA send blood to the RV The RV then has the aorta and the LV has the PT Blood flow is correct Acyanotic Due to improper rotation of the heart

Question 47

Define transposition of the great vessels

Answer 47

The great vessels have the wrong ventricles Cyanotic

Question 48

Define tet. Of fallot

Answer 48

Features include pulmonary stenosis IVS defect Overriding aorta RV hypertrophy Oxygenated blood and deoxy blood is mixed and sent to aorta due to no septum and a big, in the way aorta

Question 49

Why is critical pulmonary stenosis cyanotic

Answer 49

Decreased pulmonary blood flow to lungs

Question 50

What are the features of critical aortic stenosis

Answer 50

Tachypnea Poor feeding Poor perfusion Hypoplastic Left Heart Syndrome Cyanotic

Question 51

Define hypoplastic left heart syndrome

Answer 51

Cyanotic Has mitral valve stenosis LV is hypoplastic with a large muscle Made worse by patent ductus atrial and atrial septal defect