bio28.txt

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Author:
itzlinds
ID:
151257
Filename:
bio28.txt
Updated:
2012-04-30 21:51:18
Tags:
human development
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Description:
human development
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  1. describe the timeline and process of fertilization:
    • egg lives 24 hrs after ovulation
    • must be fertilized in fallopian tubes
    • fertilized egg takes 4 days travel time to uterus
    • blastocyst implants uterus (6-7 days post fertilization)
    • blastocyst secretes hCG: maintains corpus luteum, corpus luteum secretes high estrogen + progesterone
  2. describe sperm migration:
    • must get to distal end of fallopian tube
    • many killed- acid/leukocytes or drain out
    • remaining 1/2 go up wrong fallopian tube
    • only 2-3000/300M make it
  3. describe capacitation:
    • process for sperm to become capable to fertilize egg (takes ~ 10 hrs in the female)
    • sperm lives ~ 3-6 days inside female
  4. describe about trying to conceive:
    • intercourse ~ 3-6 days before ( + 14 hours after) ovulation
    • rhythm method contraception unreliable
    • wider window required
    • individual conditions vary
  5. describe what is still surrounding the egge during fertilization:
    • zona pelliucida
    • extracellular space
    • granulosa cells
    • may take hundreds of sperm to penetrate, only one fertilizes
    • rest reject (membrane depolarization + cells swell)
  6. describe the Y- Sperm:
    • lighter, so faster
    • boy baby: intercourse right after ovulation
    • Y is 1st to get there
  7. describe the X sperm:
    • heavier, so slower
    • girl baby: intercourse before ovulation
    • Y use up all engery
  8. describe the hCG's role in hormonal change durging pregnancy:
    • secreted by blastocyst + placenta
    • rescues corpus luteum
    • increased estrogen + progesterone levels
    • basis for pregnancy tests
  9. describe estrongens role in hormonal change during pregnancy:
    • 30x by pregnancy term
    • from corpus luteum (1st 12 weeks), then placenta
    • stimulates tissue growth in mother and fetus
  10. describe progesterones role in hormonal changes during pregnancy:
    • from corpus luteum + placenta
    • prevents ovulation + menstration
    • prvents uterin contractions
  11. explain the transformation of the zygote into a blastocyst:
    • mitotic divison - 1st 30 days
    • second polar body- completes meiosis II
    • zygote - mitosis
    • blastomeres - chromosomes mix, single cell
    • morula - 16+ cells now in uterus
    • blastocyst - lives free for a few days, 100+ cells
    • implanted blastocyst - day 6
  12. define and provide a timeline for the completion of embrogenesis:
    • 1st - 16 days
    • gastrula: takes one week to be completly buried, ~ 14 days
    • embryogenesis: ~16 days (completion), arragnement of blastocyst into 3 layers:
    • ectoderm
    • mesoderm
    • endoderm
  13. define and provid a timeline for the completeion of organogenesis:
    • germ layes differentiate into different orans
    • neural tube: week 3, mesoderm, body cavity, week 4

    • ectoderm
    • epithela
    • epidermis
    • hair,nervous system, eye ear

    • mesoderm
    • connective tissues, cartilage, skeleton, muscle, blood

    • endoderm
    • GI + respriatory tracts, thyroid, bladder
    • week 8 - all organ systems present (now fetus)
  14. describe the role of amnion as an accessory organ:
    • filled with aminotic fluid
    • protects/allows freedom of movement
  15. describe the role of allantois as an accessory organ:
    part of umbilical cord + urinary bladder
  16. desribe the role of the chorion as an accessory organ:
    • outer most membrane
    • encloses other membranes
  17. describe the role of the yolk sac as an accessory organ:
    • produces 1st germ cell
    • blood sac
  18. describe the role of the placenta/umbilical cords as an accessory organ:
    • attached to uterine wall + fetus by umbilical cord (2 arteries/1 vein)
    • mother and fetus exchange wastes/nurtients, O2/CO2
    • mother can give IgG/drugs
    • placent secretes estrogen, progesteron, hCG
    • nutrition from placenta phase - nutirents from placenta
    • trophoblastic phase: nurients from the endometrium
  19. describe the 3 trimesters of prenatal development:
    gestation (pregnancy): 38 weeks (40 weeks based on last menstrual peroid)

    • 1st trimester
    • fertilization - 12 weeks
    • most vulnerable stage - 1/2 embryos die

    • 2nd trimester
    • weeks 13-24
    • organ system matures
    • 1st ultra sound ~ 20 weeks

    • 3rd trimester
    • week 25 - birth
    • considered term at 35 weeks
    • able to sustain life outside womb
  20. illustrate the postive feedback cycle that promotes uterine contractions during childbirth:
    • baby head pushes down, pushes against cervix
    • increased cervical stretch
    • increased oxytocin (posterior pituitary)
    • incresaed uterin contractions *psotive feedback*

    • pain
    • decreased blood flow to uterine msucles during contactions
    • stretching cervix/vagina
    • pressure on ligaments/other internal organs
  21. describe each stage of labor:
    • dilation
    • longest stage
    • cervix widens (10 cm - fully dilated)
    • "water breaks" - amniotic fluid discharge

    • expulsion
    • up to 60 min
    • baby's head in vagina to delivery
    • "crowing" (top of head becomes visible)

    • placental
    • placenta/ other membranes expelled by uterine contractions
    • "afterbirth"
  22. define lactation and describe its regulation by hormones:
    synthesis/ejection of milk from mammary glands

    • synthesis
    • prolactin (anterior pituitary)
    • each feeding stimulatins prolactine release
    • prolactine stimulates milk production: next feeding
    • milk continutes as long as nursing
    • stops 1 week without nursing
    • increased prolactine, increased milk production

    • ejection
    • "milk letdown"
    • stimulated by oxytocin (posterior pituitary)


    *produce about 1.5L/day
  23. trace the stages of development from fertilization to senescence:
    zygote (single cell) > clevage > morula (3 days) > blastocyst > gastrula (4 days) > full migration embryogenesis > embryo > organogenesis > fetus

    • neonate/newborn: birth - 6 weeks
    • infant: 6 weeks - 1 year
    • childhood: 1 year - puberty
    • adolescense: puberty - adulthood
    • adulthood
    • senescense: old age - death

    *old age: organ system begins to degrade

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