A nurse is discussing fetal circulation with a group of nursing students.The ductus venosus, foramen ovale, and ductus arteriosus are key factors in fetal circulation.Which of the following explains the purpose of these shunts in fetal circulation?
To bypass the lungs and direct oxygenated blood to the brain and body.
To ensure proper development of the fetal heart.
To regulate blood pressure in the fetus.
To facilitate gas exchange in the lungs.
The Correct Answer is A
Choice A rationale
The ductus venosus, foramen ovale, and ductus arteriosus are shunts in fetal circulation that bypass the lungs and liver, directing oxygenated blood to the brain and body. The foramen ovale allows blood to flow from the right atrium to the left atrium, bypassing the lungs. The ductus arteriosus connects the pulmonary artery to the aorta, allowing blood to bypass the lungs. The ductus venosus shunts blood from the umbilical vein to the inferior vena cava, bypassing the liver.
Choice B rationale
This choice is incorrect because the primary purpose of these shunts is not to ensure proper development of the fetal heart. While they do play a role in directing blood flow, their main function is to bypass the non-functional fetal lungs and liver.
Choice C rationale
This choice is incorrect because the shunts are not primarily involved in regulating blood pressure in the fetus. Their main function is to direct oxygenated blood to vital organs like the brain and heart.
Choice D rationale
This choice is incorrect because the shunts bypass the lungs, which are not yet functional in the fetus. Gas exchange occurs in the placenta, not the fetal lungs.
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Correct Answer is C
Explanation
Choice A rationale
The umbilical cord does not typically contain one artery and one vein. This configuration would not provide the necessary blood flow to support fetal development. The umbilical cord must have two arteries to carry deoxygenated blood and waste products from the fetus to the placenta, and one vein to carry oxygenated blood and nutrients from the placenta to the fetus.
Choice B rationale
Two veins and one artery is also incorrect. The umbilical cord must have two arteries to ensure that deoxygenated blood and waste products are efficiently transported from the fetus to the placenta. Having only one artery would not suffice for the required blood flow.
Choice C rationale
Two arteries and one vein is the correct configuration of the umbilical cord. The two arteries carry deoxygenated blood and waste products from the fetus to the placenta, while the single vein carries oxygenated blood and nutrients from the placenta to the fetus. This arrangement is essential for maintaining proper fetal circulation during pregnancy.
Choice D rationale
Two arteries and two veins is incorrect. The umbilical cord only needs one vein to carry oxygenated blood and nutrients from the placenta to the fetus. Having two veins would be redundant and unnecessary for fetal development.
Correct Answer is C
Explanation
Choice A rationale
Taking iron with milk is not recommended because calcium in milk can inhibit the absorption of iron. It is better to take iron supplements with a source of vitamin C, which enhances iron absorption.
Choice B rationale
Iron supplements typically cause constipation rather than loose stools. Common side effects include nausea, vomiting, and dark stools.
Choice C rationale
Taking iron with vitamin C enhances absorption. Vitamin C converts iron into a form that is more easily absorbed by the body, making it more effective in treating iron deficiency anemia.
Choice D rationale
Iron supplements are best absorbed on an empty stomach, but they can cause gastrointestinal discomfort. If this occurs, taking them with a small amount of food may help, but it should not be taken with dairy products or calcium-rich foods.