A nurse explains placental function. Which statement is correct?
It provides oxygen and nutrients
It produces RBCs
It blocks all harmful substances
It stores fetal waste
The Correct Answer is A
The placenta is a transient, highly vascular organ facilitating the intervillous exchange of gases and solutes between maternal and fetal circulations. It functions as a selective biological membrane that utilizes simple diffusion and active transport to sustain the fetus. Furthermore, it synthesizes essential hormones such as progesterone and lactogen.
A. It provides oxygen and nutrients: Maternal blood in the intervillous spaces transfers oxygen and glucose across the syncytiotrophoblast layer into fetal capillaries. This vital metabolic support is necessary for fetal organogenesis and cellular respiration throughout gestation. It serves as the primary life-support system for the developing fetus.
B. It produces RBCs: Erythropoiesis initially occurs in the yolk sac and later shifts to the fetal liver and spleen before the bone marrow takes over. The placenta facilitates the transport of iron required for hemoglobin synthesis but does not manufacture erythrocytes itself. Red cell production is an internal fetal process.
C. It blocks all harmful substances: Many teratogens, including ethanol, viruses like cytomegalovirus, and various pharmacological agents, readily cross the placental barrier via passive diffusion. It is not an absolute filter and cannot prevent the passage of low-molecular-weight toxins. This misconception can lead to dangerous prenatal exposures.
D. It stores fetal waste: Metabolic byproducts such as carbon dioxide and urea are continuously transferred back to the maternal circulation for excretion by the mother's lungs and kidneys. The placenta acts as a conduit rather than a storage reservoir for waste. Cumulative storage would result in fetal acidosis and toxicity.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
The mid-trimester anatomy survey is a detailed sonographic evaluation of fetal biometry and organ systems. It is timed to ensure that structures like the heart, brain, and spine are sufficiently developed for structural screening. This scan identifies congenital anomalies and placental positioning accurately.
A. 10-13 weeks: This window is typically reserved for first-trimester screening, including nuchal translucency measurement and early dating. Many internal organs are still too small for a comprehensive anatomical assessment at this stage. It is too early for a formal anatomy survey.
B. 8-10 weeks: Ultrasound at this stage is primarily used for viability confirmation and determining the number of fetuses. Embryonic development is not yet complete enough to visualize complex cardiac or neural defects. This period precedes the standard screening timeline for anatomy.
C. 28-32 weeks: Scans during the third trimester focus on fetal growth, amniotic fluid volume, and fetal well-being via biophysical profiles. While anatomy can still be seen, the increased bone density and larger fetal size can make visualization difficult. It is performed after the ideal screening window.
D. 18-22 weeks: This is the optimal period for a thorough anatomical evaluation because the fetus is large enough for clear visualization of all organs. Most major structural defects can be identified during this specific timeframe. It is the gold standard for routine obstetric anatomy screening.
Correct Answer is D
Explanation
Amniotic fluid is a complex biological solution with a neutral-to-alkaline pH ranging from 7.0 to 7.5. Rupture of membranes alters the acidic environment of the vaginal vault, which typically maintains a pH of 4.5 to 5.5. Determining the fluid chemistry is essential to confirm a diagnosis of premature rupture.
A. Glucose test: While glucose is present in amniotic fluid, its concentration is not specific enough to differentiate it from other vaginal secretions or maternal urine. It is not a standard diagnostic tool for identifying membrane rupture in clinical settings. This test lacks the necessary diagnostic sensitivity.
B. CBC: A complete blood count is used to monitor for systemic infection or chorioamnionitis following a prolonged rupture. It does not provide direct evidence of the presence of amniotic fluid itself. It serves as a secondary assessment for complications rather than a primary confirmatory test.
C. Lipid panel: Serum lipid concentrations have no clinical relevance to the diagnosis of membrane integrity. Testing for cholesterol or triglycerides provides no information regarding the contents of the vaginal pool. This is an inappropriate diagnostic approach for suspected amniotic fluid leakage.
D. pH test with a nitrazine strip: Nitrazine paper changes color from yellow to blue when exposed to the alkaline pH of amniotic fluid. This biochemical shift provides a rapid bedside confirmation of the presence of liquor in the vagina. It is a reliable method for detecting rupture of membranes.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.