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Anatomy Test 2
Human Development (fertilization, pre-embryonic stage, embryonic and fetal stages, the neonate)
9
Anatomy
Graduate
10/21/2008

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Cards

Term
  1. Embryology
  2. Embryonic Period
  3. Fetal Period
Definition
  1. the study of the origin and development of a single individual
  2. the first 8 weeks
  3. the remaining 30 weeks
Term
Embryonic Period - Week 1
Definition
  1. the zygote (fertilized oocyte) moves toward uterus
  2. blastomeres - daughter cells are formed creating the 4-cell
  3. morula - solid cluster of 12-16 blastomeres
  4. early blastocyst - around 60 cells
  5. late blastocyst - implants to uterus
Term
Embryonic Period - Week 2
Definition
  1. the inner cell mass divides into 2 sheets, the epiblast and the hypoblast
  2. the amniotic sac - formed by an extension of the epiblast (outer = amnion, inner = amniotic sac cavity), filled with amniotic fluid
  3. the yolk sac - formed by an extension of the hypoblast, digestive tube forms but not a major source for embryo, gives rise to earliest blood cells and vessels
  4. these combined are called the bilaminar embryonic disc
Term
Embryonic Period - Week 3
Definition
  1. primitive streak forms on the surface of the epiblast; forms the 3 primary germ layers
  2. endoderm - formed from migrating cells that replace the hypoblast
  3. mesoderm - formed between the epiblast and endoderm
  4. ectoderm - formed from epiblast cells that remain
Term
Embryonic Period - Week 3 (continued)
Definition
  1. the notochord forms from primitive node and ectoderm (notochord is site of future vertebral column)
  2. neurulation - ectoderm starts forming brain and spinal cord
  3. neural crest - forms sensory nerve cells
  4. somites - mesoderm forms our first body segments
Term
Embryonic Period - Week 4
Definition
  1. "tadpole shape" 
  2. embryo folds to create primitive gut (site of future digestive tube and respiratory structures)
  3. ectoderm >>> epidermis, brain, spinal chord, neural crest
  4. endoderm >>> inner epithelial lining and glands of digestive, respiratory and urinary tracts
  5. mesoderm >>> everything else
Term
Embryonic Period - Week 5-8
Definition
  1. limb buds form
  2. embryo first looks recognizably human
  3. head is disproportionately large
  4. all major organs in place
Term
The Fetal Period
Definition
  • time of maturation and rapid growth
  • cells are differentiating during the first half
  • normal births occur 38 weeks after conception
  • premature birth is one before 38 weeks
Term

Measurements of the Embryo / Fetus

Definition
  1. at 8 weeks - 3 cm
  2. at 12 weeks - 9 cm
  3. at 16 weeks - 14 cm
  4. at 20 weeks - 19 cm
  5. at 30 weeks - 28 cm
  6. at 38 weeks - 36 cm  (and 6 - 10lbs)
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