Fetal Heart & Circulation PDF

Fetal heart and circulation The unique circulatory system of a fetus, designed specifically support development. Special structures in fetal circulation allow the fetus to receive essential nutrients from the mother. Different from postnatal (after birth) circulation because: The lungs, kidneys, and...

Fetal heart and circulation The unique circulatory system of a fetus, designed specifically support development. Special structures in fetal circulation allow the fetus to receive essential nutrients from the mother. Different from postnatal (after birth) circulation because: The lungs, kidneys, and gastrointestinal organs ave not functional until after birth. The placenta. Nutrient and waste exchange between fetal and maternal blood occurs through the placenta. The placenta develops within the mother’s uterus and connects to the fetus through the umbilical cord, attaching to the fetal umbilicus. Blood flows from the fetus to the placenta via two umbilical arteries. Fetal blood picks up oxygen and nutrients. Carbon dioxide and waste products ave removed from fetal blood. Oxygen-rich blood then returns to the fetus through a single umbilical cord. The umbilical vein travels to the fetus's liver, joining the hepatic portal vein. One branch directs some blood into the liver, joining the hepatic portal vein. The other branch (ductus venosus) allows most of the blood to by pass the liver, emptying into the inferior vena cava. Inferior vena cava Deoxygenated blood from the fetus's lower body mixes with oxygenated blood from the ductus venosus. Mixed blood enters the right atrium of the heart. Deoxygenated blood from the upper body enters the right atrium through the superior vena cava. Right atrium → 1/3 of blood flows through the fora men oval into the left atrium joining the systemic circulation. The remaining blood in the right atrium moss into the right ventricle and is pumper into the pulmonary trunk. Small amount of blood reaches the fetal lungs, as they are non-functional before birth. Most of the blood is redirected through the ductus arteriosus a vessel that connects the pulmonary trunk to the north bypassing the lungs. Oxygenated blood circulates through the fetal body via the systemic circulation, supplying all fetal tissues  Fetal heart and circulation When the common iliac arteries branch into the external and internal iliacs arteries: Some blood flows into the internal iliac arteries and then into the umbilical arteries. This blood returns to the placenta for another round of nutrient and Gas exchange. After birth The lungs, kidneys, digestive system begin functioning, but vascular changes occur. Blood flow through the umbilical Vessels stop. The umbilical arteries are transformed into the medial umbilical ligaments. The umbilical vein becomes the ligamentum teres.. The ductus venous collapses and forms the ligamentum venosum. The foremen oval closes, leaving a remnant called the fossa ovalis. The ductus arteriosus closes off and is replaced by the ligamentum arteriosum.