Embryology 1 Flashcards
The CVS is created from which germ layer?
mesoderm
What is created in the first 2 weeks of embryonic development?
tissues for future embryo and placenta
What is created in the third week of embryonic development?
3 germ layers- ectoderm, mesoderm, endoderm
What occurs in the 4th week of development?
Recognisable body form develops and mesoderm begins to organise
What impact does lateral and cephalocaudal folding have on the cardiac field?
lateral –> creates a heart tube
cephalocaudal –> creates a tube into the thoracic region
Why does the embryo need a primitive heart tube?
To push blood/ nutrients around
Name the different sections of the primitive heart tube
Aortic roots, truncus arteriosus, bulbus cordis ventricle, atrium, sinus venosus
Which sections of the primitive heart tube are surrounded by the pericardial sac (before folding)?
Truncus arteriosus, bulbus cordis, ventricle
What does looping achieve in the primitive heart tube?
places inflow/ outflow in correct orientation
What vessels are inferior/superior in the transverse pericardial sinus?
arteries (outflow) are on top, veins (inflow) are behind
Describe the development of the sinus venousus
- R & L horn equal size
- as baby grows inflow requirements of baby change
- venous return shifts to right hand side and left horn recedes
- Right sinus horn is absorbed by enlarging right atrium
From which tissues does the right atrium develop?
Most of the primitive atrium, swallow s the sinus venosus
-recevies venous drainage from venae cava and the heart
From which tissues does the left atrium develop?
Small part of primitive atrium
absorbs proximal parts of pulmonary veins
receives oxygenated blood from lungs
Why is most of the left atrium smooth?
Absorbs pulmonary vessels
The section of the left atrium derived from the primitive atrium is called?
The left auricle
How is the oblique sinus formed?
As the left atrium expands, absorbing the pulmonary veins
Where do oxygenation and removal of CO2 occur in the embryo?
At the placenta
Where does oxygenated blood from the placenta enter the embryonic heart?
Right side (wrong side)
What direction does the shunt in the foetal heart move blood?
Right to left (as the right side receives oxygenated blood via the inferior vena cava from the placenta and this needs to be moved to the left atria via foramen ovale to be pumped around the body)
Through which vessel does oxygenated blood from the placenta move to the right atrium?
Inferior vena cava
Why do the lungs receive a small amount of blood in the embryo?
Not being used but need blood supply to help grow! Does this via a blood vessel called the ductus arteriosus
What vessel connects the placenta to the inferior vena cava?
Ductus venosus
What happens at birth when respiration begins?
Birth
-Placental support removed
ductus venous closes
-Respiration begins
LA pressure increases and this causes the foramen ovalle to close
The ductus arteriosus contracts (sensitive to 02 and this has increased)
What happens with PDA (persistent ductus arteriosus?)
After birth:
- persistent communication between descending aorta and pulmonary artery (if ductus arteriosus does not contract)
- failure of closure
- Blood shunts left to right (when should have no shunt)
- common in immature babies
