REPRODUCTIVE HEALTH NURSING.Foetal circulation-1.pptx

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1. REPRODUCTIVE HEALTH NURSING FOETAL CIRCULATION MRS ADEWALE A. L.

2. The Foetal circulation Introduction Foetal circulation refers to the circulatory system of the fetus during pregnancy. It is a specialized and unique system that allows the fetus to derives oxygen and nutrient from the mother’s blood stream (via placenta) and eliminates waste product The nutrient and oxygen are needed by the foetus for growth and development During intra-uterine life, the respiratory and alimentary system are not functioning, hence, there is little blood supply to them The foetus develops its own blood cells(RBS and WBC) The foetal haemoglobin carries 20-30% more oxygen than the adult haemoglobin .

3. The Foetal circulation cont. Key features of foetal circulation are the temporary/unique : the placenta, umbilical cord(umbilical arteries and vein), Foetal heart, ductus venosus , ductus arteriosus , Foramen ovale , hypogastric arteries. The Temporary structures Ductus Venosus : ( from a vein to a vein ) The vessel connects the umbilical vein carrying replenished, oxygenated blood from the placenta to the inferior vene -cava, bypassing the liver and organs of Digestion. 2.Foramen ovale ( oval opening): An opening between the right and left antrium . It shunts blood from the right antrium to the left antrium , bypassing the lungs 3. Ductus Arteriosus ( from an artery to an artery): It shunts deoxygenated blood from the pulmonary artery to the aorta, bypassing the lungs. 4. Hypogastric Arteries: These two vessels branch off from the internal iliac arteries and are known as umbilical arteries when they enter the umbilical cord They return deoxygenated blood to the placenta for oxygenation and replenishment

4. The Process of Foetal Circulation Replenished and oxygenated blood leaves the placenta through the fetal surface The umbilical vessels connect each other until a larger vein( umbilical vein ) is formed. The umbilical vein passes through the umbilical cord to the umbilicus of the foetus The vessel enter the abdomen of the foetus , gives a small branch to the left lobe of the liver and by anastomosis the right lobe of the liver was also supplied with blood. The major amount of the blood bypass the liver and joins the ductus venosus which carries the rest of the blood to the inferior vene cava The blood rich in oxygen now flows through the inferior vene cava to the right atrium Most of the blood (75%) shunt through the foramen ovale to enter the Left atrium, then flows into the left ventricle where it enters the aorta ( has the highest oxygen concentration in fetal circulation) Major portion of the blood goes via the branches of the ach of the aorta to the greatest vessels of the neck ( coronary and carotid arteries) to supply the brain, the heart and the upper limb.

5. Foetal circulation contd The remaining part descend to supply the chest and the abdominal cavity The deoxygenated blood from the head, neck and arms returns to the right atrium through the superior vene cava where it joins with a small stream of oxygenated blood from the inferior vene cava (though, not completely mixed) Blood flows into the right ventricle. Blood passes into the pulmonary artery, small amount supply the lungs to nourish them while the rest flows through Ductus arteriosus into the aorta- join The aorta at the junction where it arches to become descending aorta The descending aorta supplies the chest, abdominal organs kidney with blood It continues downward as the common iliac artery which divides into Internal and External iliac artery The external iliac artery continue downwards to supply the legs while the internal iliac supplies the pelvic organs. The 2 Hypogastric arteries emerges from the internal iliac arteries, collect deoxygenated blood from the pelvis and enters the umbilicus of the fetus as as the umbilical arteries to the placenta where the interchange between the maternal and fetal blood takes place for oxygenation. The impure blood from the legs return back into the inferior vene cava to join the circulation again. The whole process takes about 30seconds NOTE: The 4layers that prevent maternal blood from mixing with the fetal blood are:i ) the SYNCYTIUM II)The Cytotrophoblastic layer iii) The Mesoderm iv) The cappilary wall Diagram

6. Changes in Fetal Circulation at Birth Changes in fetal circulation is brought about by the adaptation of the newborn to extra uterine life The first important change is brought about by the respiratory effort of the child at birth Immediately after the delivery, the baby takes its breathe and cries ( vagitus ) The lungs expand and the vascular field increase and there is increased blood flow to them. The blood which has been passing through the ductus arteriosus to the aorta now flows through the pulmonary arteries to the lungs for oxygenation Within 5mins, the ductus arteriosus is no more required and closed and it eventually becomes Cardiac ligament called Ligamentum arteriosum The increase blood flow to the lungs reduces the pressure in the right atrium while there is increase in return from the pulmonary vein to the left atrium increase tension on the left atrium. The imbalance in the pressure between the right atrium and left atrium brings about the closure of foramen ovale . Foramen ovale later become fibrosed and form adult intra-septum known as Fossa Ovalis .

7. Change in fetal circulation contd The 2 nd change is brought about by the clamping of the cord, blood circulates in the umblical vein ceases and the vein collapse to become Ligamentum Venosum and later form a support for the portal vein to inferior vene cava The Hypogastric arteries atrophy to become Obliterated hypogastric arteries ( form a ligament between the bladder and the umblicus ) except a few centimetres which remain patent and become Internal iliac and Superior vesical arteries