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10 Cards in this Set
- Front
- Back
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Identify the three prenatal periods |
Pre-Embryonic periods (weeks 1-2)
Embryonic period (weeks 3-8)
Fetal period (weeks 9-38) |
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Describe what occurs during and shortly after implantation. Include in your answer the following terms:
trophoblast cytotrophoblast syncytiotrophoblast chorion placenta inner cell mass (embryoblast) bilaminar disc epiblast amnion hypoblast |
1. Egg is fertilized and becomes a zygote
2. Egg moves done uterine tube > cleavage; divides like crazy > becomes 16 cell (morula)
3. Enters uterus as blastocyst. 2 parts: - Inner Cell Mass aka Embryoblast (becomes embryo) - Trophoblast (becomes fetal half of placenta)
4. Embeds in wall of uterus, trophoblast and inner cell mass divide: - Trophoblast: cytotrophoblast (embryo) syncytiotrophoblast (maternal side of trophoblast) Both become the chorion and fetal half of placenta -Inner Cell Mass epiblast: becomes amnion hypoblast: becomes yolk sac Both make up the bilaminar disk
5. End with a bilaminar disk ready for gastrulation |
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Describe the process and results of gastrulation |
Gastrulation - formation of the 3 germ layers. Epiblast and hypoblast > ectoderm, mesoderm and endoderm.
Primitive streak forms > epiblast cells go inside (invagination) > fill space between the epiblast and hypoblast > now have a 3 germ layer disk.
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Name the three primary germ layers and their derivatives in gastrulation. |
1. Ectoderm: skin, nervous tissue, brain
2. Mesoderm: (everything else), muscle tissue, heart, kidneys, reproductive organs, connective tissue
3. Endoderm: digestive and respiratory systems |
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Describe transverse and cephalocaudal body-folding of the embryo. |
Body folds transversely and sagitally. Forms noto chord which becomes spine. |
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Outline the steps involved in neurulation |
Process is called induction: notochord signals the ectoderm to form the neural plate
1. Mid week three - ecoderm is signaled by notochord to form the neural plate
2. (Late week three) - neural plate stars forming neural groove
3. (Early week four) - Neural groove comes together at top > neural tube > spinal cord.
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Explain what occurs during oreganogenesis |
Organ development; rudimentary systems have developed by week 8
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Describe what occurs during the fetal period |
(Weeks 9 - 38) growth and maturation of existing organs |
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What is a premature birth? How early can a baby be born and survive? |
Any baby born before week 38 Be born at week 22 and survive |
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List the primary causes and state the prevalence of birth defects |
Chromosomal, Monogenic, Major environmental, multifactorial, unknown (50%) |
