Nokea
Approximately 3 days after fertilization, what is the term for the developing zygote, which is a 16-cell mass?
- A. Trophoblast
- B. Morula
- C. Blastocyst
- D. Embryoblast
Correct Answer: B
Rationale: The correct answer is B: Morula. At approximately 3 days post-fertilization, the zygote undergoes multiple cell divisions, forming a 16-cell mass known as a morula. This stage precedes the formation of a blastocyst, which occurs around day 5. The trophoblast refers to the outer layer of cells in the blastocyst responsible for implantation, while the embryoblast is the inner cell mass that gives rise to the embryo. Therefore, the morula stage accurately represents the 16-cell mass at this specific developmental timeline.
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Sally comes in for her first prenatal examination. This is her first child. She asks you (the nurse), 'How does my baby get air inside my uterus?' The correct response is:
- A. The baby's lungs work in utero to exchange oxygen and carbon dioxide.
- B. The baby absorbs oxygen from your blood system.
- C. The placenta provides oxygen to the baby and excretes carbon dioxide into your bloodstream.
- D. The placenta delivers oxygen-rich blood through the umbilical artery to the baby's abdomen.
Correct Answer: C
Rationale: The placenta functions by supplying oxygen and excreting carbon dioxide to the maternal bloodstream.
With regard to the development of the respiratory system, maternity nurses should understand that:
- A. The respiratory system does not begin developing until after the embryonic stage.
- B. The infant's lungs are considered mature when the lecithin/sphingomyelin [L/S] ratio is 1:1, at about 32 weeks.
- C. Maternal hypertension can reduce maternal-placental blood flow, accelerating lung maturity.
- D. Fetal respiratory movements are not visible on ultrasound scans until at least 16 weeks.
Correct Answer: C
Rationale: A reduction in placental blood flow stresses the fetus, increases blood levels of corticosteroids, and accelerates lung maturity.
A woman asks the nurse, 'What protects my baby's umbilical cord from being squashed while the baby's inside of me?' The nurse's best response is:
- A. Your baby's umbilical cord is surrounded by connective tissue called Wharton jelly, which prevents compression of the blood vessels and ensures continued nourishment of your baby.
- B. Your baby's umbilical floats around in blood anyway.
- C. You don't need to worry about things like that.
- D. The umbilical cord is a group of blood vessels that are very well protected by the placenta.
Correct Answer: A
Rationale: Wharton jelly surrounds the umbilical cord and prevents compression of the blood vessels.
A woman's cousin gave birth to an infant with a congenital heart anomaly. The woman asks the nurse when such anomalies occur during development. Which response by the nurse is most accurate?
- A. We don't really know when such defects occur.
- B. It depends on what caused the defect.
- C. They occur between the third and fifth weeks of development.
- D. They usually occur in the first 2 weeks of development.
Correct Answer: C
Rationale: The cardiovascular system is the first organ system to function in the developing human. Blood vessel and blood formation begins in the third week, and the heart is developmentally complete in the fifth week.
With regard to prenatal genetic testing, nurses should be aware that:
- A. Maternal serum screening can determine whether a pregnant woman is at risk of carrying a fetus with Down syndrome.
- B. Carrier screening tests look for gene mutations of people already showing symptoms of a disease.
- C. Predisposition testing predicts with near certainty that symptoms will appear.
- D. Presymptomatic testing is used to predict the likelihood of breast cancer.
Correct Answer: A
Rationale: Maternal serum screening identifies the risk for the neural tube defect and the specific chromosome abnormality involved in Down syndrome.