Stages of Development and Neural Tube Defects

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Questions and Answers

What is the term for a newly fertilized ovum?

  • Blastocyst
  • Zygote (correct)
  • Placenta
  • Embryo

What is the size of a zygote at the point of fertilization?

  • Similar to a small marble
  • Approximately 1 inch long
  • About the size of a grape
  • The size of the period at the end of a sentence (correct)

What structure develops after implantation to nourish the embryo?

  • Umbilical cord
  • Placenta (correct)
  • Zygote
  • Fetus

At what stage of development is a fetus just over one inch long?

<p>After 11 weeks (B)</p> Signup and view all the answers

What is the term for the newly fertilized ovum?

<p>Zygote (B)</p> Signup and view all the answers

At 8 weeks, how long is the embryo approximately?

<p>1¼ inches (D)</p> Signup and view all the answers

When does the placenta begin to form in the development process?

<p>After implantation (A)</p> Signup and view all the answers

What process occurs when the blastocyst embeds itself in the inner uterine wall?

<p>Implantation (A)</p> Signup and view all the answers

What connects the fetus to the placenta?

<p>Umbilical cord (B)</p> Signup and view all the answers

During which period did cell division in the embryo double approximately every 24 hours?

<p>First week (A)</p> Signup and view all the answers

How long is a newborn infant after 9 months of development?

<p>About 20 inches (D)</p> Signup and view all the answers

What develops in the embryo by 8 weeks of gestation?

<p>Central nervous system (B)</p> Signup and view all the answers

What is the correct sequence of embryonic development stages following fertilization?

<p>Zygote, blastocyst, placenta, fetus (D)</p> Signup and view all the answers

During which stage does the fetus continue to grow and develop its organs?

<p>Fetal stage (B)</p> Signup and view all the answers

How much heavier does the infant grow from fertilization to term?

<p>50 times (C)</p> Signup and view all the answers

What happens to the rate of cell division in the embryo after the first eight weeks?

<p>It slows down significantly. (C)</p> Signup and view all the answers

What is the primary consequence of an adverse influence during the early stages of embryonic development?

<p>Permenant impairment in development (C)</p> Signup and view all the answers

Which of the following neural tube defects is characterized by the absence of brain tissue?

<p>Anencephaly (A)</p> Signup and view all the answers

How many pregnancies in the United States are typically affected by neural tube defects each year?

<p>Approximately 3000 (C)</p> Signup and view all the answers

What is the hallmark of spina bifida?

<p>Incomplete closure of the spinal cord (B)</p> Signup and view all the answers

When does the critical period for neural tube closure occur during gestation?

<p>Weeks 4 to 8 (C)</p> Signup and view all the answers

What typically happens to pregnancies affected by anencephaly?

<p>They often end in miscarriage (A)</p> Signup and view all the answers

What tissues or organs are specifically mentioned as being impaired by early adverse influences during development?

<p>Brain and spinal cord (C)</p> Signup and view all the answers

Which of the following is NOT classified as a neural tube defect?

<p>Cleft palate (D)</p> Signup and view all the answers

What is the recommended amount of fruits for pregnant and lactating women?

<p>2 cups (A)</p> Signup and view all the answers

How much protein foods should pregnant and lactating women consume daily?

<p>5½–6½ oz (D)</p> Signup and view all the answers

What is included in a sample breakfast for pregnant and lactating women?

<p>Whole-wheat English muffin with peanut butter (A)</p> Signup and view all the answers

Which vegetable is part of the sample dinner provided?

<p>Stewed tomatoes (C)</p> Signup and view all the answers

What is the range of recommended vegetable intake for pregnant and lactating women?

<p>2½–3 c (A)</p> Signup and view all the answers

What is a recommended drink for a midmorning snack?

<p>Cranberry juice (B)</p> Signup and view all the answers

Which food group has a recommended amount of 6–8 oz for pregnant and lactating women?

<p>Grains (A)</p> Signup and view all the answers

What dairy product is included in the sample menu for lunch?

<p>Low-fat milk (D)</p> Signup and view all the answers

What sources are recommended for obtaining sufficient folate?

<p>From a combination of supplements, fortified foods, and a diet rich in fruits, juices, green vegetables, and whole grains (B)</p> Signup and view all the answers

Why do pregnant women have an increased need for vitamin B12?

<p>Because B12 activates the folate enzyme (A)</p> Signup and view all the answers

What is the primary concern for vegans regarding vitamin B12?

<p>They require daily supplements or fortified foods to prevent deficiency (B)</p> Signup and view all the answers

What function does iron serve for pregnant women?

<p>It supports maternal health and fetal development by increasing blood volume and meeting fetal iron needs (D)</p> Signup and view all the answers

What can happen if a woman enters pregnancy with inadequate iron stores?

<p>Her fetal iron supply will be prioritized over her own, risking her health. (C)</p> Signup and view all the answers

How does the placenta regulate iron transfer to the fetus?

<p>It prioritizes the fetal iron needs over the mother's. (B)</p> Signup and view all the answers

What complicates iron levels in women after childbirth?

<p>They may experience blood losses that can deplete their iron supply. (B)</p> Signup and view all the answers

What dietary elements are suggested to help meet a pregnant woman's nutritional needs?

<p>Whole grains, green vegetables, fruits, and juices (B)</p> Signup and view all the answers

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Study Notes

Stages of Development

  • Zygote Formation: A fertilized ovum forms a zygote, roughly the size of a period. Rapid cell division occurs within the first week.
  • Blastocyst and Implantation: The zygote evolves into a blastocyst, which floats to the uterus for implantation.
  • Embryonic Growth: By 5 weeks, the embryo is about ½ inch long, forming a placenta for nourishment.
  • Fetal Development After 11 Weeks: The fetus measures over 1 inch long, featuring an umbilical cord and blood vessels linking it to the placenta.
  • Newborn Size: After 9 months, a newborn infant is approximately 20 inches long, having grown 20 times in length and 50 times in weight since 8 weeks.

Neural Tube Defects

  • Prevalence: About 3,000 pregnancies in the U.S. are affected by neural tube defects annually.
  • Types of Defects: Common defects are anencephaly (absence of brain) and spina bifida (incomplete spinal cord closure).
  • Anencephaly: Occurs when the neural tube doesn’t close at the upper end, leading to severe outcomes; typically results in miscarriage or early infant death.
  • Spina Bifida: Involves incomplete closure around the spinal cord, resulting in various complications.

Nutritional Needs During Pregnancy

  • Dietary Recommendations:
    • Fruits: 2 cups
    • Vegetables: 2½–3 cups
    • Grains: 6–8 ounces
    • Protein Foods: 5½–6½ ounces
    • Milk: 3 cups
  • Folate Importance: Essential for fetal development; should come from supplements, fortified foods, and a balanced diet rich in fruits and vegetables.
  • Vitamin B12: Pregnant women require more B12 to activate folate enzymes; vegans need to supplement due to dietary restrictions.
  • Iron Requirements: Increased blood volume and fetal needs elevate iron needs; sufficient maternal iron stores are critical, as the fetus draws from them.
  • Placental Iron Transfer: The placenta prioritizes fetal iron needs, impacting maternal health and potentially leading to deficiencies postpartum.

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