Podcast
Questions and Answers
What significant development occurs just two weeks after conception?
What significant development occurs just two weeks after conception?
At what point in prenatal development do the first neurons and synapses develop?
At what point in prenatal development do the first neurons and synapses develop?
What is the zygote's status during the first two weeks of prenatal development?
What is the zygote's status during the first two weeks of prenatal development?
Which layer of the embryonic disc will form the skin and nervous system?
Which layer of the embryonic disc will form the skin and nervous system?
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At what stage is the developing human referred to as a fetus?
At what stage is the developing human referred to as a fetus?
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What happens during the folding of the neural plate?
What happens during the folding of the neural plate?
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When does early learning begin in the fetus, and what can it respond to?
When does early learning begin in the fetus, and what can it respond to?
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During which stage do major organs and structures begin to develop?
During which stage do major organs and structures begin to develop?
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What shape does the neural tube resemble after the neural plate has folded?
What shape does the neural tube resemble after the neural plate has folded?
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Which of the following is NOT a characteristic of the fetal stage?
Which of the following is NOT a characteristic of the fetal stage?
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What significant developmental feature is formed during the germinal stage?
What significant developmental feature is formed during the germinal stage?
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Which stage of prenatal brain development is characterized by the development of the three-layered embryonic disc?
Which stage of prenatal brain development is characterized by the development of the three-layered embryonic disc?
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By what day are chemical signals sent to the ectoderm to initiate the growth of the neural plate?
By what day are chemical signals sent to the ectoderm to initiate the growth of the neural plate?
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What happens during the embryonic stage by the end of the second month?
What happens during the embryonic stage by the end of the second month?
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Which statement is true regarding the viability of the fetus?
Which statement is true regarding the viability of the fetus?
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What percentage of zygotes typically survive beyond the first two weeks?
What percentage of zygotes typically survive beyond the first two weeks?
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Study Notes
Prenatal Development
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Prenatal development, also called antenatal development, spans from conception to birth (typically nine months).
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Fertilization initiates the process.
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Stages:
- Zygote: Conception to 2 weeks
- Embryo: 2 weeks to 8 weeks
- Fetus: 9 weeks to birth
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Conception: Sperm fertilizes egg, requiring healthy egg release, egg migration, and sperm penetration.
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Germinal Stage (first 2 weeks):
- Zygote moves to uterus and implants.
- Placenta and umbilical cord form.
- Cell differentiation begins.
- Fewer than half of zygotes survive past 2 weeks.
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Embryonic Stage (weeks 2-8):
- Developing organism attaches to uterus, becoming an embryo.
- Major organs and structures start developing.
- Embryo grows to 1 inch by the end of the phase.
- Primitive eyes, nose, lips, teeth, arms, and legs begin forming.
- Heartbeat develops.
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Fetal Stage (2 months to birth):
- Embryo becomes a fetus at 8 weeks.
- Significant growth occurs.
- Muscle contractions and movement develop.
- Fetal position develops.
- First bone cells appear.
- Head, leg, and feet movements develop.
- Quickening (mother feeling fetal movement) around 4th month.
- Viability (ability to survive outside the womb) around seventh month.
- Average birth weight and length at 7.5 pounds and 20 inches, respectively, at birth's end.
Prenatal Brain Development
- Brain development begins in the first trimester.
- Most structural brain features established by the 8th week.
- Neural plate, folding into a neural tube forms by week 4 (brain and spinal cord).
- Neurons and synapses appear by week 7, allowing movement.
- Cerebral cortex thickens and becomes more complex during the second trimester.
- Myelin appears on neuronal axons, accelerating information processing.
- Early learning activities occur during the third trimester, including response to sound and recognition of familiar sounds (mother's voice).
- Embryonic disc forms 3 layers (ectoderm, mesoderm, endoderm).
- Ectoderm develops skin, hair, and nervous system.
- By day 15, head and brain develop.
- Nervous system development (weeks 3-4).
- Chemical signals create a thickened neural plate by day 18.
- Neural plate folds into a neural tube (precursor to brain and spinal cord) by week 4.
- Tube seals except at ends; openings close.
- Defined swelling at the top of the tube appears by week 3.5.
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Description
Explore the fascinating stages of prenatal development from conception to birth. This quiz covers key phases including the zygote, embryo, and fetus, as well as critical processes like fertilization and implantation. Test your knowledge on how life begins and develops in the womb.
