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Pregnancy and human_development
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Pregnancy and human_development

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  • 1. PREGNANCY & HUMAN DEVELOPMENT
  • 2. Fertilization oocyte viable 12 - 24 after ovulation sperm retain fertilizing power within female reproductive tract 12 - 48 hours some “super sperm” viable for 72 hours about 5 days a month that pregnancy can occur
  • 3. Sperm Transport acidity within the vagina is hostile to sperm & some leak from vagina or die almost immediately many cannot penetrate cervical mucus in uterus thousands are killed by leukocytes only a few thousand finally reach uterine tubes
  • 4. Capacitation membranes must become fragile so that hydrolytic enzymes in their acrosomes can be released
  • 5. Acrosomal Reaction acrosomal reaction: release of acrosomal enzymes that occurs in immediate vicinity of oocyte hundreds of acrosomes must rupture to break down intercellular cement of oocyte single sperm makes contact with oocyte
  • 6. Sperm Penetration nucleus is pulled into oocyte cytoplasm only one sperm is allowed to penetrate Fusion of nuclear material occurs to complete fertilization
  • 7. Preembryonic Development fertilized egg is now called a zygote
  • 8. 1. Cleavage & BlastocystFormation cleavage: period of rapid mitotic divisions following fertilization daughter cells become smaller & smaller results in a high surface-to-volume ratio for greater uptake of oxygen & nutrients
  • 9. blastomeres: – 2 identical cells by 36 hours – 4 identical cells by 60 hours – 8 identical cells by 72 hoursmorula: berry-shaped – 100 cell 4-5 days
  • 10. Implantation 6 days after ovulation implantation begins completed by 14 day 1
  • 11. Placentationformation of placentahighly vascularfully functional as nutritive, respiratory,excretory, & endocrine organ by end of2nd month of pregnancysome harmful substances can passplacental barriers 1
  • 12. teratogens: may cause severecongenital abnormalities or even fetaldeath – alcohol, nicotine, drugs, infections 1
  • 13. Events of Embryonic Development 1
  • 14. Formation & Roles ofEmbryonic Membranes amnion: sac that becomes filled with amniotic fluid which bathes cells – provides buoyant environment & protection against physical trauma – helps maintain temperature – as kidneys develop urine is added to fluid – water portion is exchanged 3 hours 1
  • 15. yolk sac: blood cell formation &produce gonadschorion: forms placentaallantois: constructs umbilical cord – becomes part of bladder 1
  • 16. Gastrulation: Germ LayerFormation Ectoderm Mesoderm Endoderm 1
  • 17. Ectodermall nervous tissueskin, hairs, sebaceous & sweat glands,& nailstooth enamelepithelium of: oral & nasal cavities,anal canal, pineal & pituitary glands 1
  • 18. Mesodermskeletal, smooth, & cardiac musclecartilage, bone & other CTblood, bone marrow, lymph tissueureters, kidneys, gonads 1
  • 19. Endoderm epithelium of digestive tract liver, pancreas thyroid, parathyroid, & thymus glands 1
  • 20. Effects of Pregnancy on Mother 2
  • 21. Anatomical Changes breasts enlarge & areolae darken “mask of pregnancy” pigmentation of facial skin uterus enlarges lordosis placenta produces the hormone relaxin, that causes ligaments to relax & become flexible for child birth weight gain about 25 lbs 2
  • 22. Gastrointestinal System excessive salivation morning sickness: increase of hormones heartburn: esophagus & stomach is crowded constipation: motility of digestive tract declines 2
  • 23. Urinary Systemurination more frequent & sometimesuncontrollableuterus compresses bladderkidneys also have to dispose of fetalwastes 2
  • 24. Respiratory System lung volume decreases nasal stuffiness 2
  • 25. Cardiovascular System total body water rises as safeguard against blood lose during birth blood volume increases 25 - 40 % blood pressure & pulse rise uterus presses on pelvic blood vessels, venous return from lower limbs may be impaired & result in varicose veins 2
  • 26. ParturitionBirth 280 days after conception 2
  • 27. Initiation of Labor last few weeks of pregnancy estrogen reaches highest levels myometrium becomes increasingly irritable & weak which may cause Braxton Hicks contractions or false labor oxytocin is released by posterior pituitary which causes expulsive contraction of true labor 2
  • 28. Stages of Labor 2
  • 29. Dilation time from labor’s onset until cervix is fully dilated (10 cm) contractions begin in upper part of uterus & move downward toward vagina contractions 15 - 30 minutes apart & last for 10 - 30 sec. contractions become more vigorous & rapid 2
  • 30. infant’s head is forced against cervixcausing it to soften & become thinneramniotic fluid breakslasts 6-12 hours 3
  • 31. Expulsion from full dilation to delivery contraction every 2 - 3 minutes & lasting 1 minute lasts 20 minutes to 2 hours crowning episiotomy may be performed to reduce tearing umbilical cord is clamped & cut 3
  • 32. Placental delivery of placenta within 15 minutes of birth important that all placental fragments be removed called afterbirth 3