Development Of The CV System 1 Flashcards
(30 cards)
What germ layer is the CV system derived from ?
Mesoderm
In what week during embryological development does folding occur ?
4th week
What effect does lateral flooding of the embryo have on early development of the heart ?
Creates the heart tube
What effect does cephalpcaudal folding have on the early development of the heart ?
Brings the tube into the thoracic region
Why must the primitive heart tube be divided ?
To create the 4 chambers
What does the primitive heart tube sit within ?
The pericardial cavity
List in order of outflow to inflow of blood in the primitive heart tube , the structures of the tube.
1) aortic roots
2) truncus arteriosus
3) bulbus cordis
4) ventricle
5) atrium
6) sinus venosus
What is the first key developmental event that occurs to the primitive heart tube ?
Looping
Describe the process of looping
- primitive heart tube elongates
- it runs out room so it twists and folds up.
- this places the inflow and outflow in the correct orientation with respect to eachother
The right atria develops from which components of the primitive heart tube ?
- MOST of the primitive atrium
- the sinus venosus
The left atria develops from which part of the primitive heart tube ?
- a very small portion of the primitive atrium
- absorbs proximal parts of the pulmonary veins
Right atria receives what ?
Venous drainage from the body ( vena cava ) and the heart ( coronary sinus)
Left atria receives what ?
Oxygenated blood from the lungs
How is the oblique sinus formed ?
Formed as left atrium expands by absorbing the pulmonary veins
Do the lungs work in the fetus ?
No
What is required to maintain fetal life , since the lungs don’t work ?
Shunts
With the lungs not working in the fetus , where does oxygenation and removal of co2 occur?
At the placenta
What is a very important requirement for the shunts ?
They must be immediately reversible at birth
Which chamber does oxygenated blood first enter during fetal circulation ?
The right atrium
Outline the fetal circulatory process
1) oxygenated blood enters the placenta from the mother
2) the oxygenated blood by-passes the liver with a circulatory shunt
3) oxygenated blood enters the inferior vena cava into the right atrium
4) SMALL amounts of blood enter the right ventricle to allow normal development of the muscular walls of ventricles and atria.
5) the small amounts of blood that enters the right ventricle enters the pulmonary trunk , where it is then bypasses the lungs with another circulatory shunt into the aorta - where it is the pumped around the body.
6) the large amounts of blood that enters the right atrium by passes the right ventricle and lungs directly into the left atrium - left ventricle - aorta - oxygenated blood around the body - leaves the placenta as deoxygenated blood.
What is the circulatory shunt called - the one that helps the oxygenated blood by pass the liver ?
Ductus venosus
Foramen ovale
Circulatory shunt that helps blood by pass the right ventricle and lungs , into the left atrium,
Ductus arteriosus
Allows blood that enters the pulmonary trunk from the right ventricle from the right atria to by pass the lungs into the aorta.
Why is the ductus venosus important ?
Because it prevents the oxygenated blood to be used up by the liver as the liver is highly metabolically active and would use it all up. This ensures that the correct amount of oxygenated blood is ,transported around the body..
