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22 Cards in this Set
- Front
- Back
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Embryology
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study of development of unicellular zygote into a complete multicellular organism
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Egg fertilization
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-12-24 hours after ovulation
-occurs in the lateral, widest portion of oviduct where sperm encounters egg |
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Fraternal twins
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conceived when more than one egg is fertilized
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Cleavage
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-rapid mitotic cell division of zygote right after fertilization
-increase in cell # without growth of cell protoplasm -increase surface-volume ratio |
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Indeterminate cleavage
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cleavage in which cells retain ability to develop into complete and normal embryo
ex. identical twins |
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Determinate cleavage
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cells whose future differentiation pathways are determined for a cell
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Cleavage occurance
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1st: after 32 hours
2nd: after 60 hours 3rd: after 72 hours then embryo reaches uterus |
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Morula
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solid ball of embryonic cells
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Blastulation
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occurs when morula develops into blastocoel
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Blastocoel
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fluid filled cavity which leads to formation of hollow sphere of cells called blastula
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Gastrulation
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-forms three layered structure called gastrula
-ectoderm, endoderm, and mesoderm |
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Ectoderm
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integument, lens of eye, retina, and nervous system
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Endoderm
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epithelial linings of digestive and respiratory tract, liver, pancrease, thyroid, bladder lining
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Mesoderm
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musculoskeletal system, circulatory system, excretory system, gonads, connective tissue throughout body, part of digestive and respiratory organs
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Embryonic membranes
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-chorion
-allantois -amnion -yolk sac |
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Chorion
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moist membrane lines inside of shell permitting gas exchange
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Allantois
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-saclike struction involved in respiration & excrettion .
-contains blood vessels for oxygen, carbon dioxide, water, and nitrogenous wastes transport -enlarges and becomes umbilical vessels |
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Amnion
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encloses amniotic fluid providing aq env't for protection from shock
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Yolk sac
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-encloses yolk
-blood vessels in yolk transfer food to embryo |
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Nonplacental internal development
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body of mother protects young but without placenta which limits exchange or food and oxygen
ex. marsupials |
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Placental Internal Development
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-system that provides oxygen and nutrients to fetus while removing carbon dioxide and metabolic waste
-components include placenta & umbilical cord |
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Stages of child labor
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1. cervix thins and dilates & amniotic sac ruptures
2. rapid contractions resulting in birth of baby & cutting of umbilical cord 3. uterus contracts expelling placenta & umbilical cord |
