Decreased surfactant production in the preterm lung is a problem because surfactant
dilates the bronchioles, decreasing airway resistance.
provides transportation for oxygen to enter the blood supply.
keeps the alveoli open during expiration.
causes increased permeability of the alveoli.
The Correct Answer is C
Choice A) dilates the bronchioles, decreasing airway resistance: This is not the correct function of surfactant.
Surfactant is a substance that reduces the surface tension of the fluid that lines the alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. Surfactant does not affect the diameter of the bronchioles, which are the small airways that branch from the bronchi. Bronchodilation and bronchoconstriction are regulated by the autonomic nervous system and various mediators, such as histamine, epinephrine, and acetylcholine.
Choice B) provides transportation for oxygen to enter the blood supply: This is not the correct function of surfactant. Surfactant does not transport oxygen or any other gas. Oxygen diffuses from the alveoli into the capillaries, where it binds to hemoglobin in the red blood cells. The red blood cells then transport oxygen to the tissues via the blood circulation. Surfactant does not play a role in this process.
Choice C) keeps the alveoli open during expiration: This is the correct function of surfactant. Surfactant prevents the alveoli from collapsing during expiration by lowering the surface tension of the fluid that lines them. This allows for easier breathing and better gas exchange. Without enough surfactant, the alveoli tend to collapse and stick together, causing atelectasis, which is a condition where some or all of a lung collapses. Atelectasis can lead to hypoxia, respiratory distress, and infection.
Choice D) causes increased permeability of the alveoli: This is not the correct function of surfactant. Surfactant does not increase or decrease the permeability of the alveoli, which is the ability of substances to pass through them.
Permeability of the alveoli depends on several factors, such as pressure gradients, solubility, molecular size, and membrane thickness. Increased permeability of the alveoli can occur in conditions such as acute respiratory distress syndrome (ARDS), where fluid leaks into the alveolar space and impairs gas exchange. Surfactant does not cause this condition, but it can be affected by it.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A: This is incorrect because lanugo is a fine, downy hair that covers the fetus in utero. It usually disappears by the 36th week of gestation, but it may persist in some preterm infants. Lanugo helps to retain body heat and protect the skin from amniotic fluid. Lanugo is not a sign of postmaturity, but of prematurity or intrauterine growth restriction.
Choice B: This is incorrect because a short, chubby appearance is typical of a term infant, who is born between 37 and 42 weeks of gestation. A term infant has a well-developed subcutaneous fat layer that gives them a rounded shape and smooth skin. A term infant also has a head circumference that is proportional to their body length and weight. A short, chubby appearance is not a sign of postmaturity, but of normal development.
Choice C: This is incorrect because vernix caseosa is a white, cheesy substance that covers the fetus in utero. It usually decreases by the 40th week of gestation, but it may remain in some term infants, especially in the skin folds. Vernix caseosa helps to moisturize and protect the skin from amniotic fluid and infection. Vernix caseosa is not a sign of postmaturity, but of term or near-term gestation.
Choice D: This is the correct answer because cracked, peeling skin is a common sign of postmaturity, which occurs when the infant is born after 42 weeks of gestation. A postmature infant has a loss of subcutaneous fat and water that results in dry, wrinkled, and desquamated skin. A postmature infant also has a large head circumference that is disproportionate to their body length and weight. Cracked, peeling skin indicates prolonged exposure to amniotic fluid and placental insufficiency.
Correct Answer is B
Explanation
Choice A: This is incorrect because acetylsalicylic acid (ASA), also known as aspirin, is not a cure for preeclampsia, but a preventive measure. ASA may reduce the risk of preeclampsia in some high-risk women by inhibiting platelet aggregation and improving blood flow to the placenta. However, ASA is not recommended for all pregnant women, as it may have adverse effects on the mother and the fetus, such as bleeding, premature closure of the ductus arteriosus, or fetal growth restriction.
Choice B: This is the correct answer because delivery of the fetus is the only definitive treatment for preeclampsia, as it eliminates the source of the placental factors that cause the condition. Preeclampsia is a multisystem disorder characterized by hypertension, proteinuria, and edema that occurs after 20 weeks of gestation. It is caused by abnormal placentation and endothelial dysfunction that lead to vasoconstriction, inflammation, and coagulation.
Delivery of the fetus and the placenta resolves these abnormalities and restores normal maternal physiology.
Choice C: This is incorrect because antihypertensive medications are not a cure for preeclampsia, but a symptomatic management. Antihypertensive medications may lower the blood pressure and reduce the risk of maternal complications, such as stroke, seizure, or organ damage. However, antihypertensive medications do not address the underlying cause of preeclampsia and do not improve fetal outcomes. Moreover, some antihypertensive medications are contraindicated in pregnancy due to their teratogenic effects.
Choice D: This is incorrect because magnesium sulfate is not a cure for preeclampsia, but a prophylaxis for eclampsia. Eclampsia is a severe complication of preeclampsia that involves seizures and coma. Magnesium sulfate is an anticonvulsant that prevents or treats eclamptic seizures by stabilizing neuronal membranes and reducing cerebral edema. However, magnesium sulfate does not lower blood pressure or improve renal function in preeclamptic women. It also has side effects such as nausea, flushing, headache, or respiratory depression.
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