Cardiovascular system

Question 1

How does the cardiac mesoderm form?

Answer 1

1. endoderm becomes restricted to inside the embryo (where the heart will develop)
2. visceral mesoderm generates cardiac progenitors, which will form cardiac crescent within the cranial lateral plate mesoderm
3. two thin-walled endocardial tubes emerge. This tubular heart will elongate, forming dilations and sacculations. It is formed by:
   i. epicardium
   ii. myocardial mantle
   (cardiac jelly)
   iii.endocardium
4. aortic arches and sinus horn start to develop. The first vessels appear as angioblasts.

Question 2

What is the aorta? How is it important?

Answer 2

The aorta is one of the most important vessel that we have: it is responsible for the pushing the blood from the left ventricle to the rest of the body.

Question 3

What is the arterial system?

Answer 3

The arterial system is formed by all the vessels that bring blood from the heart to the rest of the body.
It develops from the aortic arches (vascularization of pharyngeal/bronchial arches):
- arch 1 and 2 will disappear after 29 day
- arch 3 will develop into the carotid arteries
- arch 4 will develop into the subclavian artery
- arch 6 will develop into the pulmonary artery
Some of the most important arteries, other than the aorta, are:
- dorsal aorta
- ventral aorta
- vitelline artery
- umbilical artery
- coronary arteries

Question 4

What is the venous sytem?

Answer 4

The venous system is fromed by three systems of paired veins that drain blood into the heart:

1. vitelline
2. umbilical
3. cardinal

Question 5

How do the venous system develop from embryonic development to adult?

Answer 5

The venous system develops from the Sinus horn, the vessel that is attached to heart and allow entry of the blood into the atrium through cardinal veins. The sinus horns are the pre-sinus venous.

1. right common and anterior cardial vein will develop into the superior vena cava
2. right vitelline duct will develop into the inferior vena cava.

Question 6

How does the heart develop?

Answer 6

During development the tubular heart elongates, forming four chambers ( two atria and two ventricles). The tubular heart is formed by:
1. truncus arteriosus
2. bulbus anteriosus
3. ventricle
4. atrium
5. sinus venosus
These structures are then bent in an S-shape (due to 2. and 3. growing faster than the other structures), and the septa is formed: the septa is derived by the smooth inner heart surface which form the primitive trabeculae.
   - at week 4: endocardial cushion septum
      * atrial
         - septum primum
         - ostium primum
         - foramen secundum
      * ventricular
         - muscular interventricular septum
      * spiral septum
         - cavum aorticum
         - cavum pulmonare

Question 7

How is blood circulation different between pre- and post- birth?

Answer 7

PRENATAL CIRCULATION

• ductus arteriosus closes due to muscular compression, raising pressure in right atrium
• stop of placental bloodflow decrease pressure in right atrium
• foramen ovale close
• cut umbilical cord

POSTNATAL CIRCULATION

• deoxygenated blood from the body travels into right atrium of the heart; then it is pushed in the right ventricle, which is pushed into the lungs, where it is oxygenated.
• oxygenated blood from lungs travels into left atrium; then moves into left ventricle and is pushed into the body through the aoirta