Cardio Embryology (Khan ?'s only)

Question 1

Where is the first evidence of heart formation?

Answer 1

Splanchnic layer of lateral plate mesoderm (just said splanchnic layer in class)

Question 2

What type of cells are within splanchnic mesoderm?

Answer 2

Cardiac Myoblasts

Question 3

What are Cardiac Myoblasts derived from?

Answer 3

Cardiac Progenitor cells induced by underlying pharyngeal endoderm

Question 4

What do blood islands in the Splanchnic layer form?

Answer 4

Endothelial lined tubes and transitory blood vessels, definitive blood cells come from mesoderm around aorta later from liver even later from bone marrow

Question 5

Where does the future heart begin?

Answer 5

Cranial part of embryo, Buccopharyngeal membrane is landmark for this, it its just cranial to the buccopharyngeal membrane

Question 6

What is the cardiogenic field?

Answer 6

Endothelial lined tubes and myoblasts formed by the previous blood islands, just cranial to the buccopharyngeal membrane

Question 7

What is above the cardiogenic field?

Answer 7

Pericardial cavity which is derived from the embryonic cavity

Question 8

What brings the heart into its natural anatomical position?

Answer 8

Cranial and caudal folding of the embryo brings the heart into the thoracic region

Question 9

What forms the two endothelial lined tubes on both sides of the heart?

Answer 9

Blood islands produce angiogenic cells that dissolve into endothelial lined tubes, they eventually become endocardial regions of the heart

Question 10

What happens to endothelial tubes?

Answer 10

Fold into the midline and fuse to form a single endocardial tube

Question 11

What surrounds endocardial tube (cell type)?

Answer 11

Myoblasts that will become the myocardium of the heart

Question 12

What surrounds endocardial tube and eventually disappears, & serves no function?

Answer 12

Cardiac Jelly

Question 13

List the invaginations of the endocardial tube.

What will each of these invaginations ultimately form?

Answer 13

Truncus arteriosus -> aorta and pulmonary trunk, Bulbus cordis ->inf. Part of aorta and pulmonary trunk & adjacent parts of two ventricles, Primordial ventricles -> ventricles, primordial atria -> atria, sinus venosus-> Right horn becomes right atrium, left becomes coronary sinus

Question 14

How does blood enter the primitive heart ? (Before Atria/Ventricle portioning)

Answer 14

Sinus venosus

Question 15

How are the atria and ventricles partitioned?

Answer 15

Endocardial cushions grow towards each other, partitions atria from vessels and ventricles (produces a pattern with two holes penetrating septum that divides atria from ventricles)

Question 16

Describe the formation of the AV valves

Answer 16

Dense mesenchyme and myoblasts present, cavitation occurs and cells die, some are replaced by connective tissue which becomes chordate tendinae

Question 17

What direction is blood originally shunted in atria?

Answer 17

From right to left (mix of oxygenated and deoxygenated blood)

Question 18

What is the crescent shape fold that grows down from the roof of the atria (initially in atrial Septation)? What related structure is formed?

Answer 18

Septum primum

Osteum primum

Question 19

What happens after Osteum primum is formed at the top of the crescent shape fold?

Answer 19

Osteum secundum (maintains shunting after closure of osteum primum)

Question 20

What is the second structure that grows downward from the roof of the atria?

Answer 20

Septum secundum

Question 21

What develops in this structure?

Answer 21

Foramen ovale

Question 22

What causes blood to be shunted from RA to LA, after heart is divided into R/L V/A?

Answer 22

Pressure in RA is higher than L, pushes blood through foramen ovale to LA

Question 23

How is blood shunted after birth, and why?

Answer 23

Pressure changes , LA is higher and maintains valve closure if it already has not fused

Question 24

What is the function of the ductus arteriosus?

Answer 24

Short circuits lungs, sends oxygengated blood from RA directly into aorta

Question 25

What is the muscular part of the two ventricles derived from?

Answer 25

Develops from a ridge between the two ventricles

Question 26

What forms the membranous part of the two ventricles?

Answer 26

Cotruncal (spiral ) septum descending to meet the endocardial cushion in the muscular ridge

Question 27

What is probe patency of foramen ovale?

Answer 27

Foramen ovale did not fuse, no effect because it is a one way valve, present in 25% of pop.

Question 28

Describe the condition of excessive resorption of septum primum.

Answer 28

Causes L to R shunt

Question 29

Describe the condition of absence of septum secundum.

Answer 29

L to R shunt

Question 30

What is a common atrium?

Answer 30

No attempt at partitioning of atria at all, causes L to R severe shunting

Question 31

Describe defects in ventricular septum.

Answer 31

Occur in membranous part of septum: 1. systemic blood goes back into pulmonary circuit, too much blood pushing through pulmonary trunk 2. increased resistance 3. hypertrophy of RV 4. shunts blood from R to L 5. cyanosis called Eisenmenger complex

Question 32

Defects in Septation of truncus arteriosus , describe Tetralogy of Fallot.

Answer 32

Aortic arch and pulmonary trunk are shifted to R pulmonary trunk is smaller and aorta is much larger *eisenmenger complex + cyanosis

Question 33

Describe persistent truncus arteriosus

Answer 33

No Septation of aorta and pulmonary trunk, only one vessel leaving heart causes cyanosis *always accompanied by membranous ventricular defect (otherwise would be a closed system)

Question 34

Describe transposition of the great vessels.

Answer 34

Open into wrong chambers; causes R to L shunt and cyanosis occurs when AP septum fails to spiral

Question 35

Describe patent ductus arteriosus.

Answer 35

Blood goes into pulmonary trunk and gets into aorta from ductus arteriosus, can lead to eisenmenger syndrome leads to cyanosis more quickly than atrial defects

Question 36

Before birth the ductus arteriosus provides communication between what two structures?

Answer 36

Pulmonary Trunk and Aorta

Question 37

The initial two endothelial tubes that fuse to form the heart develop in what layer?

Answer 37

Splanchnic mesoderm

Question 38

Before birth, what structure overlaps the ostium secundum and appears to close it?

Answer 38

Septum secundum

Question 39

What causes tetralogy of fallot?

Answer 39

A misaligned AP septum

Question 40

Which of the aortic arches gives rise to the pulmonary arteries?

Answer 40

6th aortic arch

Question 41

Just before birth, all blood from the placenta goes through the liver. Describe its course.

Answer 41

Passes directly through via the ductus venosus

Question 42

How many aortas does a developing embryo have ?

Answer 42

Two pairs of dorsal aortas

Question 43

How does blood exit the heart?

Answer 43

Through an aortic sac ( has L and R divisions, forms 6 arches)

Question 44

Describe the aortic arches

Answer 44

Anteriorly they communicate with a horn like structure and loop out from dorsal aorta to this structure

Question 45

What does arch 3 give rise to? 4? 6?

Answer 45

3 -> common carotid and internal carotid a. 4-> R. subclavian, and arch of aorta from l. common carotid to l. subclavian, 6-> L and R pulmonary arteries and ductus arteriosus

Question 46

Why is the r. recurrent laryngeal n superior to the L?

Answer 46

A portion of aortic arch 6 disappears on the R side, on the L side the ductus arteriosus remains

Question 47

What is preductal coartication of aorta?

Answer 47

Narrowing of aorta prior to the ductus arteriosus, => ductus arteriosus remains patent, if post ductal ductus arteriosus atrophies

Question 48

What forms the common cardial vein?

Answer 48

Anterior and post. Cardinal veins, the common cardinal vein also receives umbilical veinand two vitelline veins, sinus venosus receives common cardinal v.

Question 49

What do the vitelline veins form?

Answer 49

Hepatic sinusoids, hepatic portal v. , hepatic veins, hepatic IVC

Question 50

What happens to the R. umbilical vein?

Answer 50

Atrophies

Question 51

What does the L. umbilical vein extend through the liver as?

Answer 51

Ductus venosus

Question 52

What does the sinus venosus become?

Answer 52

Hepatic portion of IVC (later he says that the vitelline veins actually forms this, somewhat misleading from his lecture)

Question 53

What do the sup. + inf. parts of vitelline veins form?

Answer 53

Hepatic and renal veins, respectively

Question 54

Describe pre-natal circulation.

Answer 54

Path 1: Umbilical v-> ductus venosus -> IVC -> foramen ovale -> LA,LV -> aorta -> systemic -> umbilical a. Path 2: SVC -> RA -> RV -> Aorta (mixes oxygenated from path 1 with deoxygenated ) -> systemic -> umbilical a.

Question 55

What does the umbilical arteries and veins atrophy to?

Answer 55

Umbilical v. -> ligamentum teres hepatis Umblicial artery -> medial umbilical ligaments