Facts about pregnancy and human development
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31 terms
Terms | Definitions |
|---|---|
 PREGNANCY- | from fertilization to birth |
| Gestation Period | last menstrual period until birth. Approximately 280 days. |
| Conceptus- | fertilization plus two wks. development |
| Embryonic development- | weeks 3-8(fetus |
| Fetal development- | week 9 to birth (fetus |
| Oocyte viable | 12 to 24 hrs |
| Sperm viable | 24 to 72 hours |
| Optimal fertilization | coitus must occur no more thanThree days before ovulation 24 hours after ovulation |
| Fertilization - sperm fuses with egg to form zygote | sperm fuses with egg to form zygote |
| Capacitation | An increase in the fragility of the membranes of sperm cells when exposed to the female reproductive tract. is required so the acrosomal enzymes can be relased to faciliate fertilization. |
| Oocyte is encapsulated by | corona radiata, zona pellucida, extracellular matrix |
| acrosomal reaction | Occurs just after sperm binds to zona pellucida; releases enzymes allowing sperm to traverse zona pellucida |
| Fast Block | membrane depolarization stops other sperm from fusing with the oocyte membrane |
| polyspermy | The fertilization of an oocyte by more than one sperm. This occurs in some animals, but in humans, blocks to polyspermy exist (the fast block and the slow block) so that only a single sperm can penetrate the oocyte. |
| Blocks to Polyspermy(multiple fertilization) | fast block, slow block |
| Slow block - | zonal inhibiting proteins (ZIPs)Destroy sperm receptors,Cause other sperm bound to receptors to detach |
| Fertilization | the pronuclei come together, chromosomes replicate, 1st mitotic division of conceptus begins |
| human chorionic gonadotropin (hCG) | Viability of the corpus luteum is maintained by this and it is secreted by the trophoblasts |
| hcG | prompts the corpus luteum to continue to secrete progesterone and estrogen |
| placenta | provides nutrients and removes waste |
| Chorion | outermost layer of the two membranes surrounding the embryo; it forms the fetal part of the placenta |
| between the 2nd and 3rd month | the placenta assumes the role of progesterone and estrogen production |
| Hormonal changes during pregnancy | increased hcG , estrogen, progesterone |
| tissue that forms placenta | Embryonic trophoblastic tissues,Maternal endometrial tissues |
| Decidua basalis | part of the endometrium that lies between the chorionic villi and the stratum basalis |
| Amnion | membrane formed from epiblast cells |
| Yolk sac | formed from hypoblast cells,Forms digestive tube, first blood cells and vessels.Source of primordial germ cells |
| Allantois | from yolk sac.Forms base of umbilical cord, part of urinary bladder |
| Chorion- | form parts of placenta, urinary bladder. Encloses embryo and all other membranes |
| Gastrulation | formation of 3 cell layers; endoderm, ectoderm, mesoderm |
| Primary Germ Layers | Serve as primitive tissues from which all body organs will derive |
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