Podcast
Questions and Answers
What is the main function of the placenta?
What is the main function of the placenta?
Nutrient and waste exchange between fetal and maternal blood.
How many umbilical arteries carry blood from the fetus to the placenta?
How many umbilical arteries carry blood from the fetus to the placenta?
Two
What is the primary reason why fetal lungs are non-functional before birth?
What is the primary reason why fetal lungs are non-functional before birth?
The ductus venosus allows most of the blood to bypass the ______.
The ductus venosus allows most of the blood to bypass the ______.
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The ductus arteriosus connects the pulmonary trunk to the aorta, allowing blood to bypass the lungs.
The ductus arteriosus connects the pulmonary trunk to the aorta, allowing blood to bypass the lungs.
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Which of these structures is NOT a remnant of fetal circulation after birth?
Which of these structures is NOT a remnant of fetal circulation after birth?
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What happens to the umbilical arteries after birth?
What happens to the umbilical arteries after birth?
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Study Notes
Fetal Circulation
- Fetal circulatory system uniquely designed for development
- Essential nutrients from mother
- Different from postnatal circulation
- Lungs, kidneys, and gut non-functional at birth
Placenta
- Nutrient and waste exchange via placenta
- Placenta develops in mother's uterus, connects to fetus via umbilical cord
- Blood flows from fetus to placenta via two umbilical arteries
- Fetal blood receives oxygen and nutrients
- Carbon dioxide and waste removed from fetal blood
Fetal Blood Flow
- Oxygen-rich blood returns to fetus via single umbilical vein
- Umbilical vein joins hepatic portal vein
- One branch of umbilical vein to liver, other (ductus venosus) bypasses liver
- Empties into inferior vena cava
- Deoxygenated blood from fetus's lower body mixes with oxygenated blood (from ductus venosus)
- Mixed blood enters right atrium
Heart Function
- Deoxygenated blood from upper body enters right atrium via superior vena cava
- 1/3 blood from right atrium flows through foramen ovale to left atrium (joining systemic circulation)
- Remaining blood in right atrium goes to right ventricle, pumped into pulmonary trunk
- Small amount of blood reaches fetal lungs (non-functional before birth)
- Most blood bypasses lungs via ductus arteriosus (connects pulmonary trunk)
Postnatal Changes
- Lungs, kidneys, and gut begin functioning
- Umbilical vessels no longer needed
- Umbilical arteries become medial umbilical ligaments
- Umbilical vein becomes ligamentum teres
- Ductus venosus becomes ligamentum venosum
- Foramen ovale closes, forming fossa ovalis
- Ductus arteriosus closes, forming ligamentum arteriosum
- Oxygenated blood circulates through fetal body via systemic circulation, providing tissues with oxygen
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Description
Explore the intricacies of fetal circulation and the role of the placenta in nutrient exchange. This quiz covers the unique design of fetal blood flow, emphasizing differences from postnatal circulation. Test your understanding of how oxygenation and waste removal occur during fetal development.
