The "Powerhouse" of the placenta that performs the exchange of nutrients is:

NCL (MP) Nursing Officer - 2020

Obstetrics & Gynaecology

Easy

Appeared in: NCL (MP) Nursing Officer - 2020

Explanation

Chorionic villi are the functional units of the placenta, acting as the primary site for nutrient, gas, and waste exchange between the mother and fetus.
These finger-like projections dramatically increase the surface area available for exchange, which is why they are metaphorically called the 'powerhouse'.
They are bathed in maternal blood within the intervillous space, allowing for efficient transport of substances across the placental barrier into the fetal circulation.

Option A: The amnion is the inner membrane that forms the amniotic sac. Its primary role is to enclose the fetus in amniotic fluid, providing protection and cushioning, not nutrient exchange.
Option B: The chorion is the outermost fetal membrane and contributes to the formation of the placenta. While the chorionic villi arise from it, the chorion itself is a broader structure, and the specific exchange occurs at the villi.
Option D: The yolk sac is crucial in early embryonic development, providing initial nourishment and serving as a site for early blood cell formation. Its function is largely taken over by the placenta after the first few weeks.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Functions of Placental Structures as background academic context rather than a clinical decision trigger.
Understanding the function of chorionic villi is essential for counseling patients about Chorionic Villus Sampling (CVS), an invasive prenatal test performed between 10 and 13 weeks of gestation to diagnose chromosomal abnormalities.
Placental insufficiency, a condition where the placenta fails to provide adequate oxygen and nutrients, often involves poorly developed or damaged chorionic villi. This can lead to fetal growth restriction (FGR) and requires close monitoring.
What if? If a pregnant patient develops severe hypertension (pre-eclampsia), the blood vessels supplying the placenta can constrict. This reduces blood flow to the intervillous space, impairing the function of the chorionic villi and compromising fetal oxygenation and growth, which may necessitate early delivery.

How to Approach the Question

First, identify the core concept of the question, which is the specific site of nutrient exchange within the placenta.
Analyze the keyword 'Powerhouse.' This metaphorical term suggests the most functionally active and critical component for the task mentioned (nutrient exchange).
Evaluate each option based on its known role in pregnancy and fetal development.
Recall that the amnion is for protection (amniotic sac) and the yolk sac is for early, temporary nutrition.
Differentiate between the chorion (the outer membrane that forms the villi) and the chorionic villi themselves (the functional, finger-like projections where exchange happens).
Conclude that the chorionic villi are the direct site of this 'powerhouse' activity, making it the most precise and correct answer.

Concept Tested & Keywords

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