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HUMAN DEVELOPMENT EARLY DEVELOPMENT

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Presentation on theme: "HUMAN DEVELOPMENT EARLY DEVELOPMENT"— Presentation transcript:

1 HUMAN DEVELOPMENT EARLY DEVELOPMENT
Cleavages: mitotic cell divisions of the zygote Morula: solid ball of about 50 cells of an embryo Blastocyst: fluid-filled cavity in the center of the morula, transformed into a hallow structure. Implantation: 6-7 days after fertilization the blastocyst attaches to the wall of the uterus. Gastrulation: Process of cell migration where two layers split into three Ectoderm, mesoderm, and endoderm: Forms all tissues and organs fig. 43-9 Amnion & Chorion:2 membranes that surround, protect, and nourish embryos By end of 3rd week, nervous system starts to form; primitive digestive system Placenta: Vital connection between mother and baby, was the chorion Supplies nutrients and oxygen & eliminates CO2 & metabolic wastes Blood supplies of mother and baby do not mix, they flow past each other

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3 HUMAN DEVELOPMENT Fetus: after 8 weeks of development
After three months most organs are developed as well as the umbilical cord which connects the the fetus to the placenta Muscular system developed, some movement 9cm long 15 grams amniotic sac develops which cushions and protects the fetus LATER DEVELOPMENT Fourth, fifth, and sixth months: tissues become more complex and specialized skeletal systems forms, strong heartbeat, 35 cm and 700 g CHILDBIRTH After about 9 months, oxytocin is released and stimulates muscle contractions called LABOR to increase cervix to 10 cm. contractions become more powerful and frequent, amniotic sac ruptures, baby is forced out of uterus and vagina attached to umbilical cord.

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5 AFTER CHILDBIRTH Prolactin: Pituitary hormone stimulating production of mild in breast tissue Stimulation of nerve cells in the breast transmits impulse to the hypothalamus. Pituitary releases 10x more prolactin than normal.


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