Why does fetal blood bypass the liver and the lungs?
The fetal circulatory system uses three shunts. These are small passages that direct blood that needs to be oxygenated. The purpose of these shunts is to bypass the lungs and liver. That’s because these organs will not work fully until after birth.
What does the ductus venosus allow blood to bypass?
The ductus venosus is a vein which largely bypasses the liver and drains most oxygenated blood directly into the inferior vena cava.
What causes closure of the ductus venosus?
Shortly after birth, blood flow and blood pressure in the umbilical sinus decrease abruptly. This causes the orifice of the ductus venosus to retract and narrow, resulting in functional closure of the vascular shunt.
Which fetal shunt bypasses the liver is the ductus?
The ductus venosus is the continuation of the umbilical vein, allowing a large part of the oxygenated blood from the placenta to join the supradiaphragmatic inferior vena cava, bypassing the fetal liver and directly connecting the right atrium.
Does ductus venosus go through the liver?
The viability of the fetus heavily relies on these shunts to adequately perfuse developing tissues and organs, especially the brain and heart. The ductus venosus is a shunt that allows oxygenated blood in the umbilical vein to bypass the liver and is essential for normal fetal circulation.
Why is it necessary for blood to pass through the liver?
Functions of the liver All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down, balances, and creates the nutrients and also metabolizes drugs into forms that are easier to use for the rest of the body or that are nontoxic.
What is the significance of the ductus venosus?
The ductus venosus allows oxygenated and nutrient-rich venous blood to flow from the placenta to the myocardium and brain. Increased impedance to flow in the fetal ductus venosus is associated with fetal aneuploidies, cardiac defects and other adverse pregnancy outcomes.
Does the ductus arteriosus allow blood to bypass the lungs?
The ductus arteriosus is a fetal vessel that allows the oxygenated blood from the placenta to bypass the lungs in utero. At birth, the lungs fill with air with the first breaths, pulmonary vascular resistance drops, and blood flows from the right ventricle to the lungs for oxygenation.
What does the ductus arteriosus help to bypass?
Because there is high resistance to blood flow in the lungs, the blood is shunted from the pulmonary artery into the aorta via the ductus arteriosus, mostly bypassing the lungs.
Which organ is bypassed in foetal circulation?
The fetal circulatory system uses 3 shunts. These are small passages that direct blood that needs to be oxygenated. The purpose of these shunts is to bypass the lungs and liver. That’s because these organs will not work fully until after birth.
What happens if the ductus venosus is absent?
Conclusions Our results and the review of literature suggest that absence of the ductus venosus is associated with a high incidence of fetal anomalies and adverse outcomes, including associated malformations, chromosomal aberrations, in utero heart failure and absence of the portal vein.
What is a shunt that bypasses the liver?
What is a portosystemic shunt? A portosystemic (liver) shunt is a blood vessel anomaly that results in blood from the abdominal organs (small bowel, large bowel, stomach, etc.) being diverted to the heart and bypassing the liver.
Which of the following is a shut to bypass the fetal liver?
The ductus venosus is a temporary blood vessel that branches from the umbilical vein, allowing much of the freshly oxygenated blood from the placenta—the organ of gas exchange between the mother and fetus—to bypass the fetal liver and go directly to the fetal heart.
Does the ductus arteriosus allows the blood from the umbilical vein to bypass the immature liver of the fetus?
The ductus venosus allows blood to bypass the immature liver in fetal circulation. The foramen ovale and ductus arteriosus are modifications that permit blood to bypass the lungs in fetal circulation.
What happens if the ductus venosus fails to close?
After birth, the ductus venosus closes due to changes in intracardiac pressures and a decrease in endogenous prostaglandins. Failure of the ductus venosus to close may result in galactosemia, hypoxemia, encephalopathy with hyperammonia, and hepatic dysfunction.
What causes the ductus arteriosus to close?
The ductus arteriosus carries blood away from the lungs and sends it directly to the body. When a newborn breathes and begins to use the lungs, the ductus is no longer needed and usually closes by itself during the first 2 days after birth.
Which fetal shunt closes first?
The ductus venosus closes during the first week of infancy and becomes the ligamentum venosum. When, in the new-born, the blood returns to the left atrium the foramen ovale closes somewhat like a door from left to right.
Why is it important for venous blood to go through the liver before returning to the heart?
The liver processes the nutrients in this blood and filters out toxic substances. The hepatic veins then carry the blood away from the liver and into the inferior vena cava, which leads to the right atrium, one of the four chambers of the heart.
Why does blood go through the liver before the heart?
Your portal vein is a blood vessel that carries blood from many organs in your abdomen (belly) to your liver. Your liver filters and processes this blood before it returns to your heart and recirculates through your body. Usually, veins carry blood toward your heart rather than to other organs.
Where does the blood enter the liver must pass through?
Blood enters the liver through the hepatic artery and the portal vein. The blood from the hepatic artery carries oxygen and helps support liver growth. The portal vein carries blood and nutrients from the intestine and delivers them to the liver cells (hepatocytes), which perform specific liver functions.
Why does fetal blood bypass the liver?
In the fetus, the ductus venosus (Arantius’ duct after Julius Caesar Aranzi) shunts a portion of umbilical vein blood flow directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver.
Is the ductus venosus oxygenated or deoxygenated?
Blood that is oxygenated by the placenta is carried to the fetus via the umbilical vein, bypasses the fetal liver via the ductus venosus, and is delivered to the fetal heart via the inferior vena cava.
What are the outcomes of absent ductus venosus –?
Of the 89 cases; 19 with isolated ADV had 100% survival. This was independent of the umbilical venous drainage in contrast to previous reports. The overall survival is 57% and 45% when there is an associated abnormality in the fetus. Isolated ADV has a favourable outcome regardless of the umbilical venous drainage.
Why does blood flow through the ductus arteriosus?
Before birth, a temporary opening called the ductus arteriosus is between the two main blood vessels leaving a baby’s heart. Those vessels are the aorta and the pulmonary artery. The opening is necessary for a baby’s blood flow before birth. It moves blood away from a baby’s lungs while they develop.
Why does the ductus arteriosus bypass the lungs?
Since fetal blood leaving the placenta is already oxygen-rich, and the lungs are non-functional, the ductus arteriosus allows some of this blood to bypass the pulmonary circulation to enter directly into the systemic circulation.
Why is the blood that drains into the hepatic portal circulation nutrient rich?
The blood that drains into the hepatic portal circulation is nutrient-rich because it comes from the stomach and small intestine.
Why are the lungs largely bypassed by the circulating blood in the fetus?
In the fetus, the placenta does the work of breathing instead of the lungs. As a result, only a small amount of the blood continues on to the lungs. Most of this blood is bypassed or shunted away from the lungs through the ductus arteriosus to the aorta.
Why does most blood bypass the lungs in fetal pigs?
Why is pulmonary circulation bypassed in the unborn fetal pig, and how is it bypassed? It is bypassed because the blood from the anterior vena cava and posterior vena cava is already oxygenated from the placenta. Blood flows through a hole in the septum, the foramen ovale, from the right atrium to the left atrium.
Why does blood not travel to and from the lungs in a fetal heart?
Because there is high resistance to blood flow in the lungs, the blood is shunted from the pulmonary artery into the aorta via the ductus arteriosus, mostly bypassing the lungs.
Why does blood not need to flow to the baby’s lungs?
The lungs are not used while a fetus is in the womb because the baby gets oxygen directly from the mother’s placenta. The ductus arteriosus carries blood away from the lungs and sends it directly to the body.
What is ductus venosus?
How does the ductus venosus carry blood?
How does ductus venosus work?
Why is a ductus venosus necessary during hepatic development?
Imagine you’re a little fetus, still growing in your mom’s belly. You’re getting all your food and oxygen through the placenta, right? Well, that blood, rich with nutrients and oxygen, travels through the umbilical cord and directly into the inferior vena cava (a big vein in your body).
Now, normally, that blood would travel to the liver for processing, but in a developing fetus, the liver isn’t fully ready to do its job yet. It’s still developing and can’t handle the entire blood flow coming from the placenta.
That’s where the ductus venosus comes in. It’s a special blood vessel that acts like a shortcut, allowing a large portion of the blood from the inferior vena cava to bypass the liver and go straight to the heart.
But why bypass the liver? Well, it all comes down to efficiency.
The liver plays a vital role in filtering the blood, removing waste products, and processing nutrients. However, in a developing fetus, the liver is still maturing and can’t handle the full workload. By bypassing the liver, the ductus venosus ensures that oxygen-rich blood gets to the heart quickly, where it can be pumped throughout the body, supporting the baby’s growth and development.
Think of it like this: Imagine you’re building a new house. You have all these materials arriving at the site – wood, bricks, etc. But your construction crew is still small and can’t handle all the materials at once. So, you create a bypass route to bring the materials directly to the parts of the house that need them most. This way, you can continue building the house without everything getting bogged down.
The ductus venosus is kind of like that bypass route for the fetal blood. It ensures that the heart gets the oxygen-rich blood it needs to keep the baby growing and developing.
Now, you might be wondering, what happens to that blood once it reaches the heart? Well, it’s mixed with the blood returning from the rest of the body, and some of it will go to the lungs (though remember, the lungs aren’t fully functional yet). However, because the fetal lungs are not yet active, they only take up a small amount of the blood that goes through them.
The rest of the blood circulates through the body and back to the placenta, picking up more nutrients and oxygen, starting the cycle all over again.
After birth, the ductus venosus is no longer needed. As the baby starts breathing on its own and the liver matures, the ductus venosus gradually closes off. It usually shrinks and becomes a ligament called the ligamentum venosum, which is a small, fibrous remnant that you can see on an adult liver.
Think of it like this: You’re driving down a highway, and there’s a detour. You take the detour, and then, once the roadwork is finished, you go back to the main highway. The ductus venosus is like the detour – it’s a temporary route that helps blood flow efficiently until the baby is ready for the “main highway.”
So, in summary: The ductus venosus bypasses the liver in a developing fetus because the liver isn’t fully ready to handle the blood flow from the placenta. It allows oxygen-rich blood to go directly to the heart, supporting the baby’s growth and development. After birth, the ductus venosus closes, and its function is taken over by the mature liver.
Now, let’s answer some frequently asked questions about the ductus venosus:
1. What happens if the ductus venosus doesn’t close after birth?
If the ductus venosus doesn’t close properly, it can lead to a condition called patent ductus venosus, which is a rare but serious condition. In this case, blood continues to flow through the ductus venosus, bypassing the liver. This can result in high blood pressure in the lungs and other complications.
2. How is patent ductus venosus diagnosed?
Patent ductus venosus can be diagnosed during a routine ultrasound examination. It can also be diagnosed by a doctor listening for unusual heart sounds.
3. How is patent ductus venosus treated?
Treatment for patent ductus venosus depends on the severity of the condition. In some cases, it might close on its own. In other cases, medication or surgery might be necessary.
4. Is the ductus venosus the only way blood bypasses the liver in a developing fetus?
No, the ductus venosus isn’t the only way blood bypasses the liver in a developing fetus. Another important structure, called the foramen ovale, acts as a bypass for blood flowing between the right and left atria of the heart. The foramen ovale allows blood to bypass the lungs, which aren’t functioning yet.
5. What are the other functions of the liver in a developing fetus?
The liver is a busy organ, even when it’s still developing. Here are a few of its functions:
* Production of bile: Bile helps with the digestion and absorption of fats.
* Production of clotting factors: These proteins help stop bleeding.
* Storage of iron and glycogen: Iron is essential for making red blood cells, while glycogen is a form of stored energy.
* Metabolism of drugs and toxins: The liver helps break down and remove harmful substances from the body.
The liver is a vital organ for the health of the fetus, and its development is crucial for the baby’s survival.
Remember, it’s always best to consult with your doctor if you have any concerns about your child’s health.
Hopefully, this has helped you understand why the ductus venosus bypasses the liver in a developing fetus. It’s a fascinating adaptation that helps ensure the baby gets the oxygen and nutrients it needs to grow and thrive.
See more here: What Does The Ductus Venosus Allow Blood To Bypass? | Why Does The Ductus Venosus Bypass The Liver
Embryology, Ductus Venosus – StatPearls – NCBI
The ductus venosus is a shunt that allows oxygenated blood in the umbilical vein to bypass the liver and is essential for normal fetal circulation. Blood becomes oxygenated in the placenta and travels National Center for Biotechnology Information
Fetal circulation: Circulation of blood in the fetus
Approximately half of the blood in the umbilical vein bypasses the liver to flow into the ductus venosus, a fetal vessel connecting the umbilical vein to the inferior vena cava. The other half flows into the Kenhub
Chapter 7 Fetal and Neonatal Hepatic Circulation – National
The ductus venosus (Figure 7.1) carries some of this blood, bypassing the liver, directly to the inferior vena cava where it joins blood from the lower trunk and extremities (26% National Center for Biotechnology Information
Ductus Venosus – an overview | ScienceDirect Topics
The ductus venosus branches from the left umbilical vein and acts as a shunt allowing freshly oxygenated blood to bypass the fetal liver and flow directly into inferior vena ScienceDirect
Clinical Significance of Ductus Venosus Waveform as Generated
The ductus venosus is a vascular shunt situated within the fetal liver parenchyma, connect-ing the umbilical vein to the inferior vena cava. This vessel acts as a bypass of the liver National Center for Biotechnology Information
Embryology, Ductus Venosus – PubMed
The ductus venosus is a shunt that allows oxygenated blood in the umbilical vein to bypass the liver and is essential for normal fetal circulation. Blood PubMed
Fetal Circulation – Stanford Medicine Children’s Health
Most of this blood is sent through the ductus venosus. This is also a shunt that lets highly oxygenated blood bypass the liver to the inferior vena cava and then to the right atrium Stanford Medicine Children’s Health
Ductus venosus | Radiology Reference Article | Radiopaedia.org
The vessel plays a critical role in the fetal circulation by shunting oxygenated and nutrient-rich umbilical venous blood from the placenta to the brain and myocardium, Radiopaedia
The Ductus Venosus | SpringerLink
The ductus venosus’s blood velocity reflects the portosystemic pressure gradient that perfuses the liver. This pressure is also dependent on the vascular resistance in the Springer
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