Which of the following functions of amniotic fluid are critical for fetal lung development? Select all that apply
It acts as a mechanical buffer against external trauma.
It allows the fetus to practice breathing movements.
It contributes to the symmetrical growth of the musculoskeletal system.
It prevents the compression of the umbilical cord.
It provides the necessary fluid medium for lung maturation.
Correct Answer : B,E
Amniotic fluid plays an essential role in fetal development, particularly in the respiratory system. It provides a fluid medium that fills the fetal lungs, necessary for lung tissue expansion and maturation. The fetus practices breathing movements by inhaling and exhaling amniotic fluid, which stimulates the growth and differentiation of the pulmonary alveoli. Normal amniotic fluid volume ranges from 500 to 1000 mL in the third trimester, and abnormalities in volume can impair lung development, leading to conditions like pulmonary hypoplasia.
Rationale for correct answers
B. Amniotic fluid allows the fetus to perform breathing movements, critical for stimulating lung expansion and promoting structural and functional maturation of the lungs.
E. It provides the necessary fluid medium inside the lungs, which maintains lung distension and facilitates alveolar growth, essential for postnatal respiratory function.
Rationale for incorrect answers
A. Acting as a mechanical buffer protects the fetus from external trauma but does not directly affect lung development.
C. While amniotic fluid supports symmetrical growth of the musculoskeletal system, this is unrelated to pulmonary maturation.
D. Prevention of umbilical cord compression ensures adequate blood flow and oxygen delivery but is not directly linked to lung development.
Take home points
- Amniotic fluid is essential for fetal lung growth by providing a fluid medium within the lungs.
- Fetal breathing movements in amniotic fluid stimulate pulmonary development.
- Mechanical protection and musculoskeletal support are important but not lung-specific functions.
- Adequate amniotic fluid volume is crucial to prevent pulmonary hypoplasia.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["A","B","C"]
Explanation
The decidua is the modified endometrial lining of the uterus during pregnancy, essential for implantation and support of the developing embryo. It comprises three distinct regions based on their relation to the implanted embryo: the decidua basalis (beneath the implantation site), the decidua capsularis (surrounding the embryo), and the decidua parietalis (lining the remaining uterine cavity). These layers facilitate maternal-fetal interface, immune modulation, and vascular adaptation necessary for fetal development. Normal thickness of the decidua varies but is generally 5 to 7 mm during early pregnancy.
Rationale for correct answers
A. The decidua basalis is the region of the endometrium directly beneath the implanted blastocyst and forms the maternal part of the placenta, crucial for nutrient exchange and trophoblast invasion.
B. The decidua capsularis surrounds the implanted embryo, enclosing it within the uterine cavity before it eventually fuses with the decidua parietalis as the pregnancy progresses.
C. The decidua parietalis lines the remainder of the uterine cavity not involved in implantation and eventually fuses with the decidua capsularis by mid-pregnancy.
Rationale for incorrect answers
D. Decidua chorion is not a recognized anatomical subdivision of the decidua; the chorion is a separate fetal membrane derived from trophoblast cells.
E. Decidua embryonalis is not a standard anatomical term for decidual regions; the term is sometimes mistakenly used but does not correspond to any specific decidual layer.
Take home points
- The decidua has three regions: basalis, capsularis, and parietalis.
- Decidua basalis forms the maternal portion of the placenta.
- Decidua capsularis encloses the embryo initially and later fuses with the parietalis.
- Proper decidual development is critical for implantation and pregnancy maintenance.
Correct Answer is C
Explanation
Fertilization is the process whereby a single sperm penetrates the oocyte cytoplasm, initiating the fusion of genetic material. This event results in the formation of a diploid zygote through the fusion of the male and female pronuclei. Fertilization triggers the completion of the oocyte's second meiotic division and initiates the first mitotic divisions. The zygote contains 46 chromosomes (23 pairs), restoring the diploid number essential for normal embryogenesis.
Rationale for correct answers
C. After sperm entry, the male and female pronuclei migrate towards each other and fuse, creating a single diploid nucleus within the zygote. This fusion marks the true completion of fertilization and the genetic unification necessary for embryonic development.
Rationale for incorrect answers
A. The formation of a blastocyst, containing an inner cell mass and trophoblast, occurs several days post-fertilization during the blastocyst stage, not immediately upon sperm-oocyte fusion.
B. Differentiation of the morula into an embryo occurs after several rounds of cleavage and compaction, occurring days after fertilization, thus not at the immediate completion of fertilization.
D. Rapid mitotic divisions producing blastomeres begin after fertilization but represent cleavage stages rather than the completion event of fertilization itself, which is specifically defined by pronuclear fusion.
Take home points
- Fertilization completion is defined by the fusion of male and female pronuclei forming a diploid zygote.
- The zygote contains 46 chromosomes, restoring diploidy essential for normal development.
- Subsequent events such as cleavage and blastocyst formation occur days after fertilization.
- Early embryogenesis depends on successful pronuclear fusion to initiate mitotic divisions.
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