Chapter 1- Embryology

Question 1

What does the truncus arteriosus give rise to?

Answer 1

Ascending aorta

Pulmonary trunk

Question 2

What does the bulbus cordis give rise to?

Answer 2

Smooth parts (outflow tracks) of the right and left ventricles

CONUS ARTERIOSUS- Right ventricle
AORTIC VESTIBULE- Left ventricle

Question 3

What structures does the endocardial cushion give rise to?

Answer 3

Atrial septum
Membranous inter-ventricular septum
Atrio-ventricular Valves (endocardial cushions of atrioventricular canal
Semilunar valves (endocardial cushions of outflow tracts)

Question 4

What does the primitive atrium give rise to?

Answer 4

Trabeculated parts of the left and right atrium + septum primum

Question 5

What does the primitive ventricle give rise to?

Answer 5

Trabeculated part of the left and right ventricle

Question 6

What does the primitive pulmonary vein give rise to?

Answer 6

Smooth part of the left atrium

Question 7

What does the left horn of sinus venous give rise to?

Answer 7

Coronary sinus

Question 8

What does the right horn if the sinus venous give rise to?

Answer 8

Smooth part of the right atrium (Sinus venarum)

Question 9

What structures derive the Superior vena cava

Answer 9

Right ANTERIOR CARDINAL vein + Right COMMON CARDINAL vein

Question 10

What is the first functional organ in the vertebrate embryo?

Answer 10

Heart

Question 11

At what week does the heart start beating spontaneously

Answer 11

4 weeks

Question 12

When does the cardiac looping begin?

What is the orientation of its polarity?

Answer 12

4th week

Left-Right polarity

Question 13

What is dextrocardia?

What is its etiology?

Answer 13

Dextrocardia is a congenial anomaly where in the heart points towards the right side of the chest instead of the left.

Defect in Left-Right DYNEIN

Dextrocardia can be seen in persons with KARTAGENER SYNDROME

Question 14

What is Primary ciliary dyskinesia?

How is it related to KARTAGENER syndrome?

Answer 14

Primary ciliary dyskinesia (PCD) is a rare CILIOPATHIC, AUTOSOMAL RECESSIVE DISORDER which causes a mutation in the components of the DYNEIN arms of the cilia lining the respiratory tract (upper and lower sinuses, Eustachian tube, middle ear), Fallopian tube, flagella of sperm cells

KARTAGENER SYNDROME refers to patients with PRIMARY CILIARY DYSPLASIA +

1. Situs inversus (reversal of the internal organs)
2. Chronic sinusitis (due to loss of Mucociliary escalator)
3. Bronchiectasis (permanent dilatation of the bronchi and bronchioles

Question 15

What gives rise to the foramen primum?

Answer 15

The downward growing of the septum primum from the superior wall of the primordial atrium towards the endocardial cushion

Question 16

What gives rise to the Foramen secundum?

What is its function

Answer 16

Foramen secundum forms as a result of apopotosis of areas in the septum primum.

These areas of apoptosis coalesce to form an opening called the Foramen secundum.

Maintains R-L shunt in Utero after obliteration of the Foramen primum

Question 17

What gives rise to septum secundum

Answer 17

Muscular ridge from ventral and medial atrial wall, grows downward, adjacent to the septum primum.

Foramen ovale forms in the middle of septum secundum

Question 18

What gives rise to the Foramen ovale?

What causes it to close after Birth?

Answer 18

Septum secundum

Increased LA pressure which pushes the septum primum firmly against the septum secundum.

The septum primum and secundum fuses to become the atrial septum

Question 19

What gives rise to the VALVE of the Foramen ovale?

Answer 19

Septum primum

Question 20

What causes patent Foramen ovale?

What is its complication?

Answer 20

Failure of the septum primum and secundum to fuse after birth

Can lead to PARADOXICAL EMBOLI
Venous thrombosis emboli that enters arterial circulation (similar to those resulting from ASD)

Question 21

What contributes to the formation of the ventricular septum?

Answer 21

1. Inter ventricular septum which grows caudal-cephalad
2. Membranous portion of the inter ventricular septum (which is contributed to the inter ventricular septum from the aorticopulmonary septum) closing the inter-ventricular Foramen.
3. Endocardial cushion also contributes to the membranous portion of the inter ventricular septum

Question 22

What is the most common congenital cardiac anomaly?

Where specifically does is develop?

Answer 22

Ventricular septal defect VSD

Membranous septum

Question 23

What is responsible for the septation and rotation of the truncus arteriosus?

Answer 23

Migration of NEURAL CREST CELLS (from the HINDBRAIN) & ENDOCARDIAL CELLS to the truncal and bulbar ridges (of bulbar cordis and truncus arteriosus)

Forming septation to produce pulmonary artery and ascending aorta

Question 24

Give examples of abnormalities associated with failure of neural crest cells to migrate

Answer 24

1. Transposition of great vessels (RV-aorta; LV-pulmonary artery
2. Tetralogy of fallot
3. Persistent truncus arteriosus

Question 25

1. What are they components of the tetralogy of fallot? 2. What type of shunt is seen here? 3. How do patients respond to a cyanotic spell? 4. What is the characteristic x-finding if tetralogy of fallot? 5. What causes tetralogy of fallot?

Answer 25

1. VSD 2. Right ventricular outflow obstruction 3. RV hypertrophy 4. Overriding aorta R-L shunt leading to early cyanosis They squat to increase systemic arterial resistance thereby blood is more likely to go from the RV through the pulmonary artery to get oxygenated in the lungs. BOOT SHAPED APPEARANCE OF HEART Abnormal migration of neural crest cells which leads to anterior and cephalad misalignment of the infundibular septum (muscular septum that separates aortic and pulmonary pathways)

Question 26

What is Pa02 of oxygen in umbilical vein? What is the Sa02 of oxygen in the umbilical vein? What is the Sa02 of oxygen in the umbilical arteries?

Answer 26

30mmHg (75-105mmHg adults) 80% Low O2 sat

Question 27

What are the 3 important vascular shunts in Utero?

Answer 27

1. Ductus venous (Umbilical vein--Ductus venous--IVC) 2. Foramen ovale (O2 blood RA-RV to the systemic circulation) 3. Ductus arteriosus (De-02 blood from PA- Aorta due to high fetal pulmonary resistance due to low 02 tension)

Question 28

What causes the closure of the shunts after birth?

Answer 28

1. Decreased resistance in pulmonary vasculature due to 02 2. Increase LV pressure > RA pressure closes Foramen ovale 3. Increased 02 & Decreased prostaglandin (from placental separation) closes ductus arteriosus

Question 29

What helps close a PDA? | What keeps a PDA patent?

Answer 29

1. INDOMETHACIN closes PDA | 2. PROSTAGLANDIN E1 & E2 kEEps PDA open.

Question 30

What is the postnatal derivative of allantois-Urachus

Answer 30

allaNtois- Urachus- mediaN umbilical ligament Urachus is part of the allantoic duct which forms a communication between the bladder and the umbilicus. It removes nitrogenous waste from the fetal bladder.

Question 31

What is the post natal derivative of the ductus arteriosus?

Answer 31

Ligamentum arteriosum

Question 32

What is the post natal derivative of the ductus venous?

Answer 32

Ligamentum venosum

Question 33

What is the post natal derivative of the Foramen ovale?

Answer 33

Fossa ovalis

Question 34

What is the post natal derivative of the notochord?

Answer 34

Nucleus pulposus (surrounded by annulus fibrosus)

Question 35

What is the post natal derivative of the umbilical arteries?

Answer 35

umbiLical arteries- mediaL umbilical ligament

Question 36

What is the post natal derivative if the umbilical vein?

Answer 36

LIGAMENTUM TERES of liver. (Contained in the falciform ligament)

Question 37

How is the primitive heart tube formed?

Answer 37

By lateral folding which directs the 2 endocardial heart tubes to fuse into a single primitive heart tube

Question 38

What is the derivative of the epicardium, myocardium and endocardium?

Answer 38

Mesoderm

Question 39

What are the COMPONENTS of a Cilia? What is the function of DYNEIN in the cilia What are the function of other cross linking proteins in the cilia?

Answer 39

1. 9 microtubule droplets arranged in a circle with 2 microtubules at its center (9+2) arrangement 2. DYNEIN connects the peripheral microtubule doublets to each other and allows for ATP-induced sliding of the doublets relative to each other. 3. Other proteins cross-link the micro-tubes and prevents simple sliding but converting the motion initiated by DYNEIN into bending of cilia.

Question 40

Complications of Primary ciliary Dyskinesia in males and females?

Answer 40

1. Decreased fertility due to immobile sperm and dysfunctional cilia in the Fallopian tubes 2. Dysfunctional cilia predisposes women to ectopic pregnancy

Question 41

When can trans-vaginal ultrasound detect fetal heartbeat?

Answer 41

Gestational week 6

Question 42

How many dilatations does the primitive heart tube form? | What are they?

Answer 42

1. Five ``` 2. Truncus arteriosus Bulbus cordis Primitive atrium Primitive ventricle Sinus venosus (L & R horns) ```

Question 43

What is the term for the junction between the smooth and trabecular surface of the RA internally? What is the outer ridge called?

Answer 43

1. Crista terminalis | 2. Sulcus terminalis (terminal sulcus)

Question 44

From which embryonic vessels are the IVC derived?

Answer 44

1. Vitelline veins 2. Posterior Cardinal veins 3. Sub-cardinal veins 4. Supra-cardinal veins

Question 45

What are the common congenital anomalies that lead to L-R shunts?

Answer 45

1. VSD 2. ASD 3. PDA

Question 46

What are the pathological sequelae of VSD

Answer 46

L-R shunt---Increased pulmonary blood flow---Pulmonary HPN | ---Hyperplasia of tunica intima and hypertrophy of tunica media---narrowing of pulmonary arteries

Question 47

What complication does long standing VSD produce apart from pulmonary HPN?

Answer 47

Eisenmenger complex- Reversal of L-R shunt to R-L shunt due to increasing pulmonary vascular resistance > Systemic peripheral vascular resistance Shunting of deoxygenated blood into systemic circulation- Cyanosis