Lecture 5 Flashcards
Which embryonic tissue gives rise to the CVS
Mesoderm
When does embryonic folding take place
4th week
Early lateral folding
Creates heart tube
Early celhalocaudak folding
Pushes the heart tube into the thoracic region
When does the primitive heart beat
22 days after fertilisation
Requires movement of gases and nutrients
As myocytes able to contrac5
Heart tube chambers
Aortic roots Truncus arteriosus Bulbous cordis Primitive ventricle Primitive atrium Sinus venosus
Cardiac looping
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
Sinus venosus development
- Right and left sinus horns are equal in size
- Venous return shifts to RHS and left sinus horn recedes
- Right sinus absorbed by enlarging right atrium
How is the right atrium derived
Using most of the right primitive atrium
Sinus venosum
Receives venous drainage from the body (vena cava) and heart (Coronary sinus)
How is left atrium derived
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
Feral circulation
Oxygenation occurs at placenta
Oxygenated blood enters RS of heart
Shunts required
Ductus venosus shunt
Between placenta and IVC to by pass liver
Foramen ovale
Between right atrium and left atrium to bypass lungs
Ductus arteriosis
Small volume of blood enters LV so it can contract to prevent muscle deterioration
Between pulmonary trunk and aorta to bypass lungs
What closes foramen ovale
First breath
LA pressure increases
