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2011-01-18 13:45:55
OB Week

Genetics, Conception and Fetal Developement
Show Answers:

  1. What is the Preembryonic Stage?
    Fertilization through the second week

    • Fertilization-clevage-morula
    • blastocyte-trophoblast- implantation
  2. What is Embryonic stage?
    • end of second week through the eight week
    • -basic structures of major body organs and exteran features
  3. What is Fetal Stage?
    end of eighth week until birth
  4. What is the clear protein layer that protects a single sperm inside the ovum? How long does it last?
    • zona pellucida
    • Disappears in 5 days.
  5. What is a zygote?
    How long does it take to travel through the fallopian tubes?
    • 1.when sperm and ovum combine to form diploid
    • 2. travels through fallopian tubes to uterus
    • 3.divides by mitoses (cleavage) and all cells are identical

    1. 3-4 days
  6. Where does fertilization take place?
    In outer third ampulla of the fallopian tube
  7. Name the three embryonic layers of cells
    Ectoderm- forms CNS, special senses, skin, and glands

    Mesoderm-forms skeletal, urinary, circulatory, and reproductive organs

    Endoderm-forms respiratory system, liver,pancreas, and digestrive system
  8. What is a morula?
    Mass of 16 cells
  9. What is a inner mass cell?
    Blastocyte- forms the embryo and amnion
  10. What is the outer mass cell?
    trophoblast- forms the placenta and chorion
  11. How long does it take for sperm to reach the fallopian tubes?
    5 minutes after intercourse
  12. How long can sperm awat the ovum? How long can Ovum survive?
    • 3-5 days (sperm)
    • 24 hours (ovum)
  13. what occurs from the Blastocyst-Trophoblast stage?
    • 3-4 more days until implants in endometrium
    • Now called blastocyst
    • Outside layer of blastocys made up of cells called tropho blasts
  14. What forms the placenta in early pregnancy?
    chorionic villi, imbed into endometrium and form the placenta
  15. How long does it take for implantation to occur?
    7-10 days
  16. What is hCG?
    Human chorionic gonadotropin- hormone preserves copus lteum and its progesterone production in order to maintain uterine lining, basis for urine and serum pregnancy tests
  17. What does Estrogen do during pregnancy?
    • causes enlargement of breasts, uterus, external genitalia,
    • stimulates myometrial contractillity
  18. What is the role of progesterone in pregnancy?
    • maintains endometrium
    • decreases contractillity of the uterus
    • provides nourishment for early conceptus
  19. What is the role of Relaxin?
    • 1.acts synergistically with progesterone to maintain pregnancy
    • 2.causes relaxation of pelvic ligaments and softens cervix to prepare for delivery
  20. Describe Fetal development at week 3
    • development of:
    • Brain
    • Spinal cord
    • Heart
    • Nerual tube forms
    • GI tract
    • Leg and arm buds appear and grow out of body
  21. What occurs during week 4 of fetal development
    • Brain differentiates
    • limb buds grow and develop more
  22. What occurs during week 5 of fetal development?
    • heart now beats at reg rhythm
    • Beginning structures of eyes and ears
    • some visible cranial nerves
    • muscles become innervated
  23. Descibe what occurs durrin week 6 of fetal development
    • Lungs begin to form
    • fetal circulation is established
    • Liver produces RBCs
    • Further develpment of brain
    • Primitive skeleton forms
    • CNS forms
    • Brain waves detectable
  24. What occurs during week 7 of fetal development?
    • Straightening of trunk
    • nipples and hair follicles form
    • elbows and toes visible
    • arems and legs move
    • diaphragm formed
    • mouth with lips and early tooth buds
  25. What occurs during week 8 of fetal development?
    • Rotation of intestines
    • facial features develop
    • Heart development is complete
    • Resembles Human being
  26. What occurs in weeks 9-12 of fetal development?
    • sexual differentiation continues
    • buds for all 20 temp teeth laid down
    • digestive system shows activity
    • head comprises nearly half of fetus size
    • face and neck well formed
    • urogenital tract completes development
    • RBC produced in liver
    • Urine begins to be produced and excreted
    • fetal gender can be determined by 12 weeks
    • lims are long thin, digits are well fomred
  27. What occurs durring weeks 13-16 of fetal development
    • Lanugo (fine hair) develops on the head
    • fetal skin is almost transparent
    • bones become harder
    • fetus makes active movements
    • sucking motions are made with the mouth
    • amniotic fluid is swallowed
    • fingernails and toenails present
    • weight quadruples
    • fetal movement or QUICKENING detected by mother
  28. What occurs weeks 17-20 during fetal development
    • rapid brain growth
    • Fetal heart tones can be heard with stethoscope

    kidneys continue to secret urine into amniotic fluid

    vernix caseosa, white greasy film covers fetus

    • eyebrows and head hair appear
    • brown fat deposited to help maintain temp
    • nails present on both fingers and toes
    • muscles well developed
  29. What occurs during week 21-24 fetal development?
    Eyebrows and eyelashes well formed

    fetus has hand grasp and startle reflex

    alveoli forming in lungs

    skin is translucent and red

    lugns begin to produce surfactant
  30. What occurs during week 25-28 of fetal development?
    Fetus reaches 15 inches in length

    rapid brain development

    eyelids open and close

    nervous system controls some functions

    fingerprints are set

    blood formation shifts from spleen to bone marrow

    fingerprints are set

    blood formations shifts from spleen to bone marrow

    fetus usually assumes head down postion
  31. What occurs during weeks 29-32 of fetal development?
    Rapid increase in amount of body fat

    Increased CNS control of body functions

    Rhythmic breathing movements occur

    Lungs are not fully mature

    Fetus stores Iron, calcium and phosphorus
  32. What occurs during weeks 33-38 of fetal development?
    Testes are in scrotum of male fetus

    Lanugo begins to disappear

    Increase in body fat

    Fingernails reach the end of fingertips

    Small breast buds are present on both sexes

    Mother supplies fetus with antibodies against disease

    Fetus isconsidered full term at 38 weeks

    Fetus fills uterus
  33. What is the concern of oligohydraminos?
    (Too little amniotic fluid) <500mL at term

    uteroplacental insufficiency

    fetal renal abnormalities
  34. What is the concernt of hydraminios?
    (Excessive amniotic fluid) >2,000mL at term

    maternal diabetes

    neural tube defects

    chromosomal deviations and malformations of CNS and/or Gi tract that prevents normal swallowing of amniotic fluid by the fetus
  35. What are the important components of the fetal blood supply?
    AVA- Artery Vein Artery

    Wharton's jelly- specialized connective tissue surrounds the three vessels preventing compression, which would cut off fetal blood and nutrient supply
  36. What is Monozygotic Vs Dizygotic twins?
    Monozyogic- comes from one zygote that separtes, produces identical twins

    Dizygotic twins- comes from 2 separate zygotes, the individuals are different and not identical
  37. What is the Chorion?
    Thick outside layer of amniotic sac

    adjacent to maternal surface of placenta