Cardiovascular system development

Question 0

Describe the 3 earliest paired veins to develop, what do they do? When do they begin development?

Answer 0

Begin developing in the 4th week.

1. ) Vitelline veins: Returns poorly oxygenated blood from the umbilical vessel (yolk sac).
2. ) Umbilical veins: Carries well-oxygenated blood from the chorion, i.e. from the placenta to the embryo; only the left umbilical vein persists.
3. ) Common cardinal veins: Returns poorly oxygenated blood from the body of the embryo.

Question 1

During what week of early embryonic development does the cardiovascular system begin to develop? What are its three major components?

Answer 1

3rd week.

The three major components are:

1. ) Splanchnic mesoderm (heart primordium)
2. ) Lateral and paraxial mesoderm
3. ) Neural crest mesenchymal cells

Question 2

What is the only adult remnant of the umbilical vein?

Answer 2

Caudal part of the left umbilical vein

Question 3

What is the significance of the DUCTUS VENOSUS?

Answer 3

It shunts blood from the umbilical vein straight to the heart, i.e. IT BYPASSES THE CIRCULATION IN THE LIVER, meaning freshly oxygenated blood from the placenta can go straight to the embryo without having to traverse all of the small spaces in the liver.

Question 4

What early structures give rise to the following:

1. ) Left brachiocephalic vein
2. ) Superior vena cava

Answer 4

1. ) Caudal part of the left anterior CARDINAL VEIN

2. ) Right anterior cardinal vein + right common cardinal vein

Question 5

When does blood flow begin a left to right directionality? How?

Answer 5

At 8 weeks the right and left anterior cardinal veins anastomose.

Question 6

What is the fate of the following structures:

1. ) Subcardinal vein
2. ) Supracardinal vein

Answer 6

1.) Becomes the stem of left renal, suprarenal, gonadal, and a SEGMENT OF THE IVC
2.) Cranially: Becomes the azygos and hemiazygos veins.
Caudally: Left degenerates. Right forms a segment of the IVC.

Question 7

What are the four main segments that proceed to form the IVC and where do they come from?

Answer 7

(p. 293 Notability)
1. ) Hepatic: from proximal part of the right vitelline.
2. ) Prerenal: from the subcardinal vein.
3. ) Renal: subcardinal-supracardinal asnastomosis.
4. ) Postrenal: right supracardinal vein.

Question 8

When do the pharyngeal arch arteries form?

Answer 8

4th-5th weeks

Question 9

Discuss the fate of the six pairs of pharyngeal arch arteries

Answer 9

(p.296 notability)
1.) First pair: Mostly disappear.
2.) Second: Dorsal aspect remains as the stapedial artery.
3.) Third: Proximal aspects give rise to COMMON CAROTIDS. Distal aspect gives rise to the INTERNAL CAROTIDS
4.) Fourth: LEFT 4th –> Gives rise to part of the ARCH OF THE AORTA. RIGHT 4th –> Gives rise to the proximal aspect of the RIGHT SUBCLAVIAN ARTERY.
5.) Fifth: Contributes nothing.
***6.) Sixth: LEFT 6th –>
a.) Proximal segment: Gives rise to the PROXIMAL LEFT PULMONARY ARTERY.
b.) Distal segment: Gives rise to a pre-natal shunt called the DUCTUS ARTERIOSIS (shunts blood from lungs while not needed).
RIGHT 6th –>
a.) Proximal segment: PROXIMAL RIGHT PULMONARY ARTERY.
b.) DISTAL PART DEGENERATES.

Question 10

Which important arteries are contributed to by the (approx. 30) intersegmental arteries (3)?

Answer 10

1. ) In the neck they join into one longitudinal artery, the VERTEBRAL ARTERY.
2. ) In the thorax they form the INTERCOSTAL ARTERIES
3. ) The fifth lumbar pair of intersegmental arteries form the COMMON ILIAC ARTERY.

Question 11

What is the fate of the vitelline arteries

Answer 11

• Vitelline arteries, 3 persist (to serve digestive system):
  1. ) Celiac trunk to the foregut (parts of esophagus, stomach, and duodenum).
  2. ) Superior mesenteric to the midgut (small intestine and proximal large intestine).
  3. ) Inferior mesenteric to the hindgut (cecum to rectum).

Question 12

What is the fate of the umbilical arteries?

Answer 12

• Umblical arteries:
  1. ) Proximal portions: give rise to INTERNAL ILIAC and VESICAL ARTERIES.
  2. ) Distal portions: give rise to the MEDIAL UMBILICAL LIGAMENTS.

Question 13

What primitive structure separates the developing heart from the primordial myocardium. What does this structure become in adults?

Answer 13

Cardiac jelly. It gives rise to subendocardial connective tissue.

Question 14

Where does blood enter the primitive heart?

Answer 14

The sinus venosus

Question 15

What causes the folding that produces the primitive atria?

Answer 15

Growth of the SINUS VENOSUS

Question 16

What early structure is responsible for partitioning the atrioventricular canal?

Answer 16

Endocardial AV cushions.

Question 17

Appearance of what structure is the first sign that the atrium is going to be partitioned?

Answer 17

p.200 BWAB

The septum primum.

Question 18

What primitive heart structure is necessary in order for the lungs to receive blood?

Answer 18

The foramen ovale

Question 19

What primitive structure gives rise to the sinus venarum (smooth wall of the right atrium) and right auricle of the right atrium?

Answer 19

The right horn of the sinus venosus

Question 20

What is the adult derviative of the left sinus venarum?

Answer 20

Coronary sinus

Question 21

What drives growth of, and gives rise to the inner smooth surface of the left atrium?

Answer 21

The primordial pulmonary veins and trunk being incorporated into the wall left atrium.

Question 22

1. ) What drives the partitioning of the ventricles?

2. ) What closes the partition?

Answer 22

p. 205 BWAB
1. ) Outer growth of the inferior myocardial tissue, i.e. overgrowth of myocardial tissue in the region of the ventricle.
2. ) Membrane emanating from the fused endocardial cushions.

Question 23

What structures within the adult heart are formed by apoptosis/cavitation of the ventricular walls during early development?

Answer 23

Trabeculae carnae, chordae tendineae, and papillary muscle

Question 24

1. ) To what heart structure does the neural crest contribute to?
2. ) Why does this structure develop in the shape that it does?

Answer 24

p. 208 BWAB
1. ) Aorticopulmonary septum: Separates venous and arterial blood at the ARTERIAL TRUNK.
2. ) The septum has a twisting shape (seems to wrap around the aorta in the adult heart) where they were once at 90 degrees to one another. This occurs due to the fluid dynamics of blood flow continually passing through during early development.