The Reproductive Syste2

The Reproductive Syste2 - • Stretching of the uterus...

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The Reproductive System Formation of the General Body Structure o The limbs develop as outgrowths called limb buds. o The face develops by the fusion of five tissue masses. Development of the Organ Systems o The GI tract develops as the developing embryo closes off part of the yolk sac. o The heart develops as two tubes fuse into a single tube that develops septa to form four chambers. o The kidneys and reproductive system are closely related in their development. Growth of the Fetus o The fetus increases 15-fold in length and 1400-fold in weight. Parturition Uterine contractions force the baby out of the uterus during labor. Increased estrogens, decreasing progesterone levels, and secretions from the fetal adrenal cortex initiate parturition.
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Unformatted text preview: • Stretching of the uterus stimulates oxytocin secretion, which stimulates uterine contractions. The Newborn Respiratory and Circulatory Changes o Inflation of the lungs at birth results in closure of the foramen ovale and the ductus arteriosus. o When the umbilical cord is cut, blood no longer flows through the umbilical vessels. Digestive Changes o The newborn digestive system only gradually develops the ability to digest a variety of foods. Lactation • Estrogens and progesterone help stimulate the growth of the breasts during pregnancy. • Suckling stimulates prolactin and oxytocin synthesis. Prolactin stimulates milk production, and oxytocin stimulates milk "letdown."...
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