20 Development (Lecture) 8 Flashcards Preview

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Flashcards in 20 Development (Lecture) 8 Deck (23):
1

Prenatal

growth prior to birth 9 mo

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Trimesters

3 mo x 3

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Pre-Embryonic phase begins ? and ends?

Begins at fertilization and ends at implantation

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*Fertilization

occurs in ampulla of fallopian tube union of sperm and egg.

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*Zygote

is a fertilized egg

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First 30 hours after fertilization

nothing happens

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*Cleavage

cell divsion with out cell growth

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*Morula

solid ball of cells that enters the uterus

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*Blastocyst

hollow sphere with a small mass of cells floats in uterus. this is what implants into wall of uterus.

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Gestation / Pregnancy begins...

at implantation

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*Extra-embryonic membranes

Amnion, Yolk, Chorion (external)

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Amnion (internal)

fluid filled sack that embryo developes in

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Yolk

structure that will produce embrionic blood

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Chorion (external)

membrane across which mother and baby exchange material becomes placenta

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Gastruation

genectic specialization of embrionic cells

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Allantois

This is the 4th extra embrionic membrane. this will serve as a temporary bladder for waste. later it becomes part of the cord.

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Limb buds

4 weeks becomes arms and legs

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Embryonic heart contractions

4 weeks

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*Fetal phase

begins at week 8

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*All organ systems present after

8 weeks

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Ossification occurs week 8

cartilage becomes bone

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Monozygotic twins

Identical zygote splits

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Dizygotic twins

ferternal two eggs