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What process marks the transformation from a single-cell zygote into a multicellular organism early in development?
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The process of cleavage, which involves rapid cell division without growth, marks this transformation.
How does the hormone relaxin contribute to pregnancy and childbirth?
Relaxin helps by relaxing the ligaments in the pelvis and softening the cervix to prepare for childbirth.
What is the purpose of the placenta during fetal development?
The placenta facilitates the exchange of nutrients and waste between the mother and the fetus, supporting fetal growth and development.
What initial structure forms from the rapid cell division of a zygote, and what is its significance?
The initial structure formed is a morula, which is significant as it prepares to develop into a blastocyst.
During the process of labor, what are the three primary stages, and what happens in each?
The three stages are: Dilation (cervix dilates), Expulsion (infant delivery), and Placental Stage (delivery of the placenta).
What factors initiate the transition from embryo to fetus?
The transition is marked by the development of major organs and bones, which characterize the change from an embryonic phase to a fetal stage.
What anatomical adaptations occur in the mother during pregnancy?
During pregnancy, mothers experience enlargement of breasts and uterus, increased blood volume, and secretion of hormones like relaxin and HPL.
Describe the role of progesterone in maintaining pregnancy before labor.
Progesterone helps maintain the uterine lining and prevents uterine contractions, protecting the pregnancy until labor.
Explain the role of Human Chorionic Gonadotropin (HCG) during implantation.
HCG is secreted by trophoblasts to maintain the corpus luteum, ensuring continued production of estrogen and progesterone for successful implantation.
What is the significance of blood volume increase during pregnancy?
Increased blood volume supports the growing needs of the fetus and prepares the mother's body for blood loss during childbirth.
Describe the primary roles of trophoblast cells in early pregnancy.
Trophoblast cells form the outer layer of the blastocyst, which will later develop into the placenta and aid in establishing the uterine blood vessels.
Explain the significance of the blastocyst's inner cell mass.
The inner cell mass of the blastocyst will develop into the embryo, giving rise to all the tissues and organs of the body.
What developmental milestones characterize the embryonic stage?
During the embryonic stage, the major structures and organs begin to form from the blastocyst.
Identify the hormone that significantly increases before labor and its function in the birth process.
Estrogen levels increase, and this hormone plays a critical role in preparing the cervix for dilation and initiating uterine contractions.
What triggers labor to start, according to hormonal changes?
Labor is initiated by a decrease in progesterone and an increase in estrogen and cortisol from the fetus, which leads to the release of oxytocin and prostaglandins that cause contractions.
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