Lecture 5

Question 1

Which embryonic tissue gives rise to the CVS

Answer 1

Mesoderm

Question 2

When does embryonic folding take place

Answer 2

4th week

Question 3

Early lateral folding

Answer 3

Creates heart tube

Question 4

Early celhalocaudak folding

Answer 4

Pushes the heart tube into the thoracic region

Question 5

When does the primitive heart beat

Answer 5

22 days after fertilisation
Requires movement of gases and nutrients
As myocytes able to contrac5

Question 6

Heart tube chambers

Answer 6

Aortic roots 
Truncus arteriosus 
Bulbous cordis 
Primitive ventricle
Primitive atrium 
Sinus venosus

Question 7

Cardiac looping

Answer 7

Tube elongates
Inflow and outflow ends move to correct configuration
Primitive atrium pushed up and posterior to ventricles
Transverse pericardial sinus forms between inflow and outflow

Question 8

Sinus venosus development

Answer 8

1. Right and left sinus horns are equal in size
2. Venous return shifts to RHS and left sinus horn recedes
3. Right sinus absorbed by enlarging right atrium

Question 9

How is the right atrium derived

Answer 9

Using most of the right primitive atrium
Sinus venosum
Receives venous drainage from the body (vena cava) and heart (Coronary sinus)

Question 10

How is left atrium derived

Answer 10

Small portion of primitive atrium - left auricle
Sprouts primitive pulmonary vein which branches and absorbs proximal parts (4 branches)
Oblique sinus formed as LA expands

Question 11

Feral circulation

Answer 11

Oxygenation occurs at placenta
Oxygenated blood enters RS of heart
Shunts required

Question 12

Ductus venosus shunt

Answer 12

Between placenta and IVC to by pass liver

Question 13

Foramen ovale

Answer 13

Between right atrium and left atrium to bypass lungs

Question 14

Ductus arteriosis

Answer 14

Small volume of blood enters LV so it can contract to prevent muscle deterioration

Between pulmonary trunk and aorta to bypass lungs

Question 15

What closes foramen ovale

Answer 15

First breath

LA pressure increases

Question 16

4th aortic arch

Answer 16

Right side - proximal part of right subclavian artery

Left side - arch of aorta

Question 17

6th aortic arch

Answer 17

Right side - right pulmonary artery

Left side - left pulmonary artery and ductus arteriosus

Question 18

Interatrial septation

Answer 18

1. Endocardium cushions develop in the antrioventricar region which divides the developing heart into left and right
2. Septum primum grows down from the atrial roof towards the fused endocardial cushions
3. Ostium primum develops before septum primum fuses so blood can freely mover between right to left
4. Before the ostium primum closes, the ostium secundum appears in the septum primum
5. Septum secundum grows which is crescent shaped. Hole = foreman ovale

Question 19

Fossa ovalis

Answer 19

Remnant of foreman ovale

Question 20

Discrete vulnerability

Answer 20

Endocardial suctions go through a different developmental process and must migrate

Question 21

Interventricular septum

Answer 21

1. Muscular component of the ventricular septum grows upwards towards the fused endocardial cushions
2. A primary interventricular foramen is produced which is filled by the membranous component made up of Ct derived from the endocardial cushion