Heart Development

Question 1

____________ forms the outer lining of the heart. The inner lining of the heart, lymphatic and blood vessels, develop from ___________.

Answer 1

Mesothelial pericardium; endothelium

Question 2

In the splanchnopleuric mesenchyme on either side of the neural plate, a horseshoe-shaped area develops as the ___________ region.

Answer 2

cardiogenic

NOTE: By day 19, an endocardial tube begins to form on both sides of this region

Question 3

By week three, the two endocardial tubes merge to form the ________.

Answer 3

Tubular heart

Question 4

The tubular heart from 5 distinct regions. List tehm from head to tail. What does each division develop into?

Answer 4

Truncus arteriosus

• Aorta and pulmonary artery

Bulbus cordis

• Right ventricle

Primitive ventricle

• Left ventricle

Primitive atrium

• Front parts of the left and right atria and their appendages

Sinus venosus

• Posterior part of the right atrium, the sinoatrial node and the coronary sinus.

Question 5

In the middle of the fourth week, the sinus venosus receives venous blood from the poles of right and left sinus. Each pole receives blood from which three major veins?

Answer 5

the vitelline vein, the umbilical vein and the common cardinal vein.

Question 6

The sinus opening moves clockwise. Why?

Answer 6

This movement is caused mainly by the left to right shunt of blood, which occurs in the venous system during the fourth and fifth week of development.

Question 7

The right and left venous valves fuse and form a peak known as the ___________.

Answer 7

septum spurium

Question 8

The left venous valve and the septum spurium fuse with the developing _________.

Answer 8

atrial septum

Question 9

The upper right venous valve disappears, while the bottom venous valve evolves into the inferior valve of the _________ and the _________valve.

Answer 9

vena cava; coronary sinus

Question 10

Tissue masses called __________ develop into atrioventricular and conotroncal regions.

Answer 10

endocardial cushions

NOTE: The cushions will help in the formation of auricular septum, ventricular conduits, atrio-ventricular valves and aortic and pulmonary channels.

Question 11

When the right of the atrium expands due to the incorporation of the pole of the sinus, a new fold appears, called the ___________.

Answer 11

septum secundum

NOTE: At its right side it is fused with the left venous valve and the septum spurium. A free opening will then appear, called the foramen ovale.