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2012-02-06 17:57:19
genetics conception fetal development

Chapter 3
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  1. Factors influencing development
    • 1. genetic code
    • 2. quality of sperm and ovum
    • 3. adequacy of intrauterine environment
    • 4. teratogens
  2. genetic risk factor: cystic fibrosis
    european, white and Ashkenazi Jewish
  3. Ashkenazi Jewish
    have the greatest number of genetic risk factors due to inbreading.
  4. Genotype
    composes what is inside; a persons genetic makeup
  5. phenotype
    composes what is outside; how genes are outwardly expressed.
  6. genetic risk factor: Tay-Sachs disease
    Ashkenazi Jewish, French-Canadian and Cajun
  7. Genetic risk factor: Sickle cell ds/trait
  8. Genetic risk factor: Thalassemia
    African, Mediterranean and Asian
  9. Conditions that prompt prenatal genetic counseling:
    chromosomal disorders, deafness, heart defects, neural tube defects, genetic disorders, clotting disorders, developmental delay/mental retardation.......
  10. Amniotic fluid: Polyhydramnios
    • Def: too much amniotic fluid; more than 2L at term.
    • Cause: imbalance of h2o exchange b/t mother, fetus and amniotic fluid
    • (Common in diabetic women)
    • Indicates: chromosomal disorders, GI disorder, Neuro tube defects, or cardiac defects.
  11. Amniotic fluid: Oligohydramnios
    Def: too little fluid; less than 500mL at term or 50% expected amount at any gestational age.

    Indicates: kidney disorder, placental insufficency
  12. Maternal portion of placenta
    Decidua; attaches to the uteran wall.
  13. Fetal portion of the placenta
    chorionic villi; fetal surface is covered by amnion

    2 arterties that carry deoxygenated blood away form fetal body.

    1 vein that carries oxygenated blood to fetal heart.
  14. Placental functions
    nutrition, excretion, fetal respiration (gas exchange), and production of hormones.
  15. Maternal blood flow/Vascular arrangement of the placenta
    maternal blood flows through the uterine arteries to intervillous spaces of the placenta and returns through the uterine veins to maternal circulation
  16. Fetal blood flow/Vascular arrangement of placenta
    Fetal blood flows through the umbilical arteries into the villous capillaries of the placenta and returns through the umbilical vein to the fetal circulation
  17. Fetal blood flow
    veins carry blood to heart

    arteries carry blood away

    Most oxygenated blood is in the umbilical vein
  18. Fetal Development: week 4
    heart begins to beat
  19. Fetal Development: week 6
    liver produces blood cells

    heart begins circulating blood
  20. Fetal Development: week 8
    all body organs are formed

    embryo is now designated as a fetus
  21. Fetal Development: week 12
    • genitals are well differentiated
    • urine is produced
    • fetal heart can be heard via doppler ultrasound
  22. Fetal Development: week 16
    active movements are present

    baby's sex can be determined
  23. Fetal Development: week 20
    subcutaneous brown fat appears

    fetal movement felt by mother (quickening)
  24. Fetal Development: week 24
    alveoli beginning to form

    weighs 780 grams

    respiratory movements begin
  25. Fetal Development: week 28
    brain develops rapidly

    nervous system begins to regulate

    lungs can provide gas exchange

    surfactant begins to form
  26. Fetal Development: week 32
    lungs maturing

    bones fully developed
  27. Fetal Development: week 36
    increase in subcutaneous fat

    lanugo begins to disappear
  28. Fetal Development: week 38
    Full Term

    head bigger than chest

    gets antibodies from mother
  29. Teratogens
    Agents: drugs, alcohol, ace inhibitors, anticonvulsants, cocaine, coumadin

    Infections/viruses: Rubella, Syphilis and toxoplasmosis, herpes varicella, cytomegalovirus.
  30. Heterozygous dominant
    possessing different alleles at a given locus; dominant gene and its recessive allele
  31. Homozygous dominant
    identical alleles; either dominant or recessive