Heart embryology

Question 1

During which week does the septum begin to form?

Answer 1

End of week 4

Question 2

What week is the heartbeat established?

Answer 2

4th

Question 3

What process forms the folds that will become the heart?

Answer 3

Cephalocaudal folding

Question 4

What primitive germ layer forms the heart wall layers?

Answer 4

Mesoderm

Question 5

H

Answer 5

U

Question 6

What are the five dilations that develop in the heart tube?

Answer 6

Truncus arteriosus, bulbus cordis, primitive left ventricle, primitive atrium, left and right horns of sinus venosus

Question 7

During primitive circulation, where does the blood enter and leave the heart tube, respectively?

Answer 7

Enters- sinus venosus

Leaves- truncus arteriosus

Question 8

When does the heart tube begin to loop and when should it be complete?

Answer 8

End of week 3, end of week 4

Question 9

What part of the heart tube will become the right ventricle?

Answer 9

Bulbus cordis

Question 10

What will the sinus venosus horns form?

Answer 10

Smooth wall of the atria

Question 11

What part of the heart tube will form the muscular walls of the atria?

Answer 11

Primitive atrium

Question 12

What will the truncus arteriosus form?

Answer 12

VOT (aorta and pulmonary trunk)

Question 13

What separates the primitive heart before the septum forms?

Answer 13

The atrioventricular sulcus separates the atrium and the ventricles.
The interventricular sulcus separates the ventricle and the bulbus cordis.

Question 14

In which direction does the septum primum grow?

Answer 14

Posterior to anterior

Question 15

What is the function of the foramen (ostium) primum?

Answer 15

A hole between the left and right atria so that blood can bypass the lungs in a developing foetus

Question 16

What does the septum intermedium separate?

Answer 16

The atria from the ventricles

Question 17

How does the foramen primum close?

Answer 17

The posterior and anterior endocardial cushions, that form the septum intermedium, joins with the septum primum, closing the hole.

Question 18

Where does the foramen secundum open and how?

Answer 18

Superior edge of the septum primum, cell apoptosis destroys the cells there creating a new opening.

Question 19

Which primitive septal wall does the foramen ovale arise from and how?

Answer 19

Septum secundum, this grows to the right of the septum primum and does not fuse with the septum intermedium, leaving the foramen ovale which will persist until birth.

Question 20

Where is the foramen ovale located?

Answer 20

Near the base of the right atrium

Question 21

What will act as the valve to close the foramen ovale at birth?

Answer 21

The septum primum

Question 22

What weeks do the AV valves form?

Answer 22

5-8

Question 23

During which weeks does the truncus arteriosus undergo septation?

Answer 23

7-8

Question 24

What divides the truncus arteriosus?

Answer 24

Conotruncal ridges

Question 25

Describe the process that forms the semilunar valves

Answer 25

The truncus arteriosus swells and connects to the right and left ventricles helically (spirally)

Question 26

How many aortic arches are there in the primitive circulation?

Answer 26

6

Question 27

Which pharyngeal arch arteries are important to remember?

Answer 27

3rd- forms common and internal carotids 4th- forms right subclavian and part of aortic arch 6th- forms ductus arteriosus

Question 28

What should the ductus arteriosus become after birth?

Answer 28

Ligamentum arteriosum

Question 29

What does the degeneration of the ductus arteriosus allow passage of?

Answer 29

Left recurrent laryngeal nerve

Question 30

What is the importance of the ductus venosus before birth?

Answer 30

Bypass the liver and deliver oxygenated blood from the placenta straight into the IVC

Question 31

What are the four identifying features of the tetralogy of fallot?

Answer 31

Pulmonary stenosis, VSD, overriding aorta and right ventricular hypertrophy