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Reproduction 3

Reproduction 3. Chapter 11.4 Objectives 11.4.9-11.4.15. List the two functions of fertilization. To form a diploid cell by fusing two haploid gametes Activation of the egg to complete Meiosis II.

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Reproduction 3

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  1. Reproduction 3 Chapter 11.4 Objectives 11.4.9-11.4.15

  2. List the two functions of fertilization. • To form a diploid cell by fusing two haploid gametes • Activation of the egg to complete Meiosis II

  3. 11.4.9 Describe the process of fertilization including the acrosome reaction, penetration of egg membrane by a sperm, and the cortical reaction. • Fertilization – occurs in oviduct (Fallopian tube) • The process in which a sperm cell fuses with an egg cell • Acrosome Reaction • Acrosome: enzyme-filled bag at the tip of the sperm • Releases enzymes that “chew” through the follicle cells and zona pellucida • Penetration • Plasma membranes fuse • Sperm nucleus enters egg cytoplasm • Triggers the completion of Meiosis II to form ovum and 2nd polar body

  4. 11.4.9 Describe the process of fertilization including the acrosome reaction, penetration of egg membrane by a sperm, and the cortical reaction. • Cortical Reaction • Occurs after the gametes have fused and Ca2+ is released from the endoplasmic reticulum into the cytoplasm • Cortical granules in the egg cytoplasm release their contents into the space between the plasma membrane and vitelline layer (just inside the zona pellucida) • This hardens the vitelline layer to create a slow, permanent block to sperm entry (occurs a few seconds after 1st sperm enters the egg) http://www.google.com/search?q=fertilization+animation&safe=active

  5. 11.4.11 Outline early embryo development up to the implantation of the blastocyst. • Zygote: fertilized egg • Morula: solid ball • Blastula: hollow ball stage • Blastocyst: 2-layered, cup-shaped embryonic stage

  6. 11.4.11 Outline early embryo development up to the implantation of the blastocyst. • Fertilized ovum = zygote • Zygote Morula (0-3 or 4 days) • Cleavage: rapid cell divisions that increase the number of cells • Morula is the same size as the zygote • Morula develops into blastocyst

  7. 11.4.11 Outline early embryo development up to the implantation of the blastocyst. • Implantation of blastocyst (6-8 days) • It contacts the uterine lining and embeds • Blood vessels start to develop • Embryo produces HCG which signifies pregnancy

  8. 11.4.10 Describe the role of human chorionic gonadotropin (HCG) in early pregnancy. • Secreted by the embryo after implantation has occurred • Targets the corpus luteum to prevent it from breaking down. • Without corpus luteum hormones, pregnancy would end • The corpus luteum secretes progesterone until placenta develops enough to take over, then the corpus luteum breaks down • High progesterone levels maintains pregnancy • ‘Overproduction’ causes HCG to be secreted in mother’s urine, which is detected on pregnancy tests.

  9. 11.4.12 Explain how the structure and functions of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy. • Placenta • structure in the uterus that exchanges blood between mother and embryo, also primary endocrine organ (produces necessary hormones) • Disk-shaped, dinner-plate sized

  10. 11.4.12 Explain how the structure and functions of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy. • Functions: • Exchange of gases, wastes, nutrients for the fetus from the mother • Grows into uterus, has blood vessels near the maternal vessels to allow for exchange • Blood does not mix • Produces hormones: estrogen and progesterone

  11. 11.4.12 Explain how the structure and functions of the placenta, including its hormonal role in secretion of estrogen and progesterone, maintain pregnancy. • Hormone functions: • Estrogen: will induce labor when levels peak • Progesterone: uterus enlargement, cessation of menstruation/ovulation, breast growth, inhibits milk • Other placental structures: • Umbilical cord: connects the fetus to the placenta • Chorionic villi: • Grows into the endometrium of uterus • Contains fetal blood vessels • This is where exchange occurs

  12. 11.4.14 State that materials are exchanged between maternal and fetal blood in the placenta. • Fetal blood passively absorbs oxygen, glucose, lipids, water, minerals, vitamins, antibodies, alcohol, drugs, some viruses • Fetal blood releases carbon dioxide, urea, hormones, and water

  13. 11.4.13 State that the fetus is supported and protected by the amniotic sac and amniotic fluid. • The fetus is supported and protected by the amniotic sac and amniotic fluid • Fluid is a shock-absorber • Free movement for fetus • Thermal stability • Breaks and leaks when a woman's "water breaks“

  14. 11.4.15 Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback. • Placenta stops producing progesterone at birth • In combination with high estrogen levels, oxytocin is released (causes uterine contractions) • This turns on release of additional oxytocin (+ FEEDBACK) • Estrogen and progesterone levels fall to zero, oxytocin rises, initiating labor

  15. 11.4.15 Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin levels and positive feedback.

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