Fetal Circulation and Birth Changes

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Questions and Answers

What structural change occurs to the umbilical arteries after birth?

They develop into the superior vesicular arteries.

They remain functional for blood circulation.

They transform into medial umbilical ligaments. (correct)

They become part of the aorta.

What happens to the foramen ovale after birth?

It remains open for blood flow.

It turns into the ligamentum venosum.

It connects the pulmonary artery to the aorta.

It closes and forms the fossa ovalis. (correct)

Which of the following describes the functional difference in blood flow from fetus to infant?

Blood flow shifts from right to left shunting.

Blood flow transitions from systemic to pulmonary.

Blood flow remains unchanged in both systems.

Blood flow changes from low to high pressure system. (correct)

What is the outcome of the ductus arteriosus after birth?

It transforms into the ligamentum arteriosum. Signup and view all the answers

What role does the umbilical vein play after atrophy?

It becomes the ligamentum teres hepatitatis. Signup and view all the answers

What is the primary role of the umbilical vein in fetal circulation?

Carries oxygenated blood from the placenta to the fetus Signup and view all the answers

How does blood bypass non-functioning lungs in fetal circulation?

Using the foramen ovale Signup and view all the answers

Which statement accurately describes the ductus arteriosus?

It diverts blood away from the lungs into the aorta Signup and view all the answers

What happens to the blood that flows from the right atrium in a fetus?

It passes through the foramen ovale to the left atrium Signup and view all the answers

During fetal circulation, which structures help to return non-oxygenated blood to the placenta?

Umbilical arteries Signup and view all the answers

Where does oxygenated blood flow immediately after reaching the fetus through the umbilical vein?

Right atrium Signup and view all the answers

What anatomical structure receives a small amount of blood routed from the ductus venosus?

Growing liver Signup and view all the answers

What is one consequence of increased blood flow to the liver in newborns?

Liver enlargement Signup and view all the answers

What role do the umbilical arteries play in fetal circulation?

They carry deoxygenated blood from the fetus to the placenta. Signup and view all the answers

What is the main reason the foramen ovale closes after birth?

Increased blood flow from the lungs raises left atrial pressure. Signup and view all the answers

What physiological change occurs to the lungs at birth?

They become a low-pressure vascular system. Signup and view all the answers

What happens to blood flow in the fetal heart?

Blood mixes freely between the atria through the foramen ovale. Signup and view all the answers

What significant pressure change occurs when the umbilical cord is clamped at birth?

Pressure in the lungs increases due to inflation. Signup and view all the answers

What is the result of the closure of the foramen ovale?

It prevents blood from flowing between the atria. Signup and view all the answers

What is a patent foramen ovale?

It is a condition where foramen ovale remains open post-birth. Signup and view all the answers

How is blood oxygenated in fetal circulation?

By the placenta which acts as an external respiratory organ. Signup and view all the answers

What causes the closure of the ductus arteriosus after birth?

Increase in oxygen tension Signup and view all the answers

What happens to blood flow after the foramen ovale closes?

Blood flows from left to right atrium Signup and view all the answers

What physical change contributes to the functional closure of the ductus venosus?

Increased pressure in the portal vein Signup and view all the answers

What condition results if the ductus venosus fails to close after birth?

Bypass of blood from the liver Signup and view all the answers

What causes the decrease in pressure in the right atrium after birth?

Loss of placental circulation Signup and view all the answers

Which of the following events does NOT contribute to the closure of the foramen ovale?

Decreased pressure in the left atrium Signup and view all the answers

What anatomical connection does the ductus arteriosus primarily serve?

Pulmonary artery to aorta Signup and view all the answers

What factors induce the constriction of the ductus arteriosus at birth?

Release of bradykinin and increased oxygen tension Signup and view all the answers

Study Notes

Fetal Circulation and Changes at Birth

Fetal circulation differs significantly from infant circulation. The fetus relies on the placenta for oxygen and nutrient delivery.
The umbilical vein carries oxygenated blood from the placenta to the fetus.
After entering the fetus, the blood flows through the inferior vena cava.
Two umbilical arteries carry deoxygenated blood and waste products back to the placenta.
Specialized structures facilitate fetal circulation:
- Ductus venosus: carries blood from the umbilical vein to the inferior vena cava, bypassing the liver.
- Foramen ovale: a hole in the heart that allows blood to flow directly from the right atrium to the left atrium, bypassing the lungs.
- Ductus arteriosus: shunts blood from the pulmonary artery to the aorta, bypassing the lungs.
Most of the oxygenated blood bypasses the lungs.
After birth, several crucial changes occur:
- Clamping the umbilical cord alters blood flow patterns.
- Increased atmospheric pressure and systemic vascular resistance lead to lung inflation and higher blood pressure in the left side of the heart, causing the following:
  - Closure of the foramen ovale.
  - Closure of the ductus arteriosus.
  - Closure of the ductus venosus.
The lungs become functional. Blood flow changes from lung bypass to the lungs.
Umbilical arteries and vein atrophy and become ligaments (ligamentum arteriosum, ligamentum venosum, and ligamentum teres).
The change in pressure results in the closure of the foramen ovale.
The changes in pressure and oxygen levels result in the closure of the ductus arteriosus.
The structure of the fetal circulatory system transforms into that of an infant.

Objectives

Discuss the anatomy and physiology of fetal circulation, including the fetal circulatory system's special structures.
Compare and contrast fetal circulation to infant circulation.
Define specialized structures of fetal circulation in detail, explaining their roles.

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Description

This quiz explores the intricacies of fetal circulation and the significant changes that occur at birth. It covers the role of the placenta, the structure of blood vessels involved, and how blood flow adjusts once the baby is born. Test your knowledge on these fundamental concepts of human anatomy and development.