Prenatal Development

• Fertilization


  Also known as conception, is the process by which sperm and ovum (sex cells) combine to create a single cell called zygote, which then duplicates itself again and again by cell division
• Ovulation


  Rupture of mature follicle in either ovary and expulsion of its ovum which occurs every month until menopause
• Dizygotic Twins


  Also known as Fraternal Twins, two separate eggs being fertilized by two different sperms, can be same or different sex, may have genetic basis
• Monozygotic Twins


  Resulted from the cleaving of one fertilized egg and are generally genetically identical
• Heredity


  Genetic transmission of heritable characteristics from parents to offspring
• Deoxyribonucleic Acid (DNA)


  Long, spiraling ladder whose steps are made of pairs of chemical units called bases (Adenine, Thymine, Cytosine, Guanine)
• Chromosomes


  Coils of DNA of smaller segments called genes
• Mitosis


  Cell division of non-sex cells
• Meiosis


  Cell division of sex cells
• Mutation


  Mistake in copying genetic code which creates permanent alteration in genetic material
• Autosomes


  Not affiliated to sexual expression
• Sex Chromosomes


  23rd pair which indicates the baby's sex (XX, female: XY, male)
• Alleles


  Produce alternative expressions of characteristics
• Homozygous


  If two alleles are the same
• Heterozygous


  If two alleles are different
• Dominant


  Allele that is always expressed or shows up as a trait in that person
• Recessive


  Usually doesn't show unless paired with another recessive trait
• Polygenetic Inheritance


  Interaction of several genes
• Phenotype


  Observable characteristics
• Genotype


  Underlying genetic makeup
• Epigenesis


  Environment can influence when and which genes turn on and off, refers to chemical molecules attached to a gene that alter the way a cell "reads" the gene's DNA, cells are susceptible to epigenetic modification during critical periods such as puberty and pregnancy
• Chromosomal Abnormalities


  • Down Syndrome (Extra copy of chromosome 21, Surgery, SPED)
  • Klinefelter Syndrome (Extra X Chromosome (XXY), Hormone Therapy)
  • Fragile X Syndrome (Abnormality in X chromosome causes ID, SPED, Speech Therapy)
  • Turner Syndrome (Missing X chromosome for females, Hormone Therapy)
  • XXY Syndrome (Extra Y chromosome, No treatment)
• Gene-Linked Abnormalities


  • Cystic Fibrosis (Overproduction of mucus in the lungs and digestive tract, Physical Therapy)
  • Diabetes (Does not produce enough insulin, Insulin)
  • Hemophilia (Delayed blood clotting, Blood transfusions)
  • Huntington's (CNS deteriorates producing problem in muscles and mental decline)
  • Phenylketonuria (Build up of Phenylalanine in the body, Special Diet)
  • Sickle-Cell Anemia (Limits body oxygen supply, Penicillin, Antibiotics, Pain Reliever)
  • Spina Bifida (Incompletely closed spinal canal, Surgery)
  • Tay-Sachs Disease (Accumulation of lipids in the NS, Medication, Special Diet)
  • Anencephaly (Absence of brain tissue, No treatment)
  • Polycystic Kidney Disease (Enlarged Kidneys, Kidney Transplant)
  • Alpha antitrypsin Deficiency (Cirrhosis of the liver in early infancy, No treatment)
  • Alpha Thalassemia (Severe Anemia; nearly all die soon after birth, Frequent Blood Transfusion)
  • Beta Thalassemia (Severe Anemia; fatal in adolescence or Young adulthood, Blood Transfusions)
  • Duchenne Muscular Dystrophy (Males with muscle weakness, minor mental retardation, No treatment)
• Carriers


  Carry one bad copy of recessive gene and one good one
• Genotype-Environment Interaction


  Effects of similar environment conditions on genetically different individuals
• Genotype-Environment Correlation


  • Passive Correlations (parents tend to provide environment that encourages the development of that trait)
  • Reactive or Evocative (children with differing genetic makeups evoke different reactions from others, other people react to the children's genetic makeup)
  • Active (actively selects or create experiences consistent with their genetic tendencies)
• Niche-Picking


  Tendency to seek out environments compatible with one's genotype
• Nonshared Environmental Effects


  Result from the unique environment in which each child in a family grows up
• Infertility


  Inability to conceive a child
• In Vitro Fertilization


  Eggs and sperm are combined in a laboratory dish
• Prenatal Diagnostic Tests


  • Ultrasound Sonography (high frequency sound waves are directed into the pregnant woman's abdomen, no risk to the woman or fetus, detect abnormalities, no. of fetuses, and sex)
  • Fetal MRI (uses powerful magnet and radio images to generate detailed images of the body's organs and structures)
  • Chorionic Villus Sampling (small sample of placenta is removed, small risk of limb deformity)
  • Amniocentesis (sample of amniotic fluid is withdrawn and tested for chromosomal and metabolic disorders)
  • Maternal Blood Screening (identifies pregnancies that have an elevated risk for birth defects)
• Gestation


  Period between conception and birth, between 37 and 41 weeks, dated from the first day of an expectant mother's last menstrual cycle
• Cephalocaudal Principle


  Development proceeds from head to the lower extremities
• Proximodistal


  Development proceeds from the center to outer parts of the body
• Early Signs and Symptoms of Pregnancy

  • Tender, Swollen breasts or nipples
  • Fatigue
  • Slight bleeding or cramping
  • Food Cravings
  • Nausea with or without vomiting
  • Frequent Urination
  • Frequent, Mild Headaches
  • Constipation
  • Mood Swings
  • Faintness and Dizziness
  • Raised Basal Body Temperature
• Germinal Stage


  From fertilization to about 2 weeks of gestational age, zygote enters into cell division (mitosis) while making its way to the fallopian tube, differentiation (specialization of the cells to perform various tasks), blastocyst (fluid-filled sphere which floats freely in the uterus until 6th day after fertilization then it implants itself in the uterine wall), trophoblast (outer layer of cells that later provides nutrition and support for the embryo), ectoderm (outer layer becomes outer layers of skin, nails, hair, teeth, sensory organs, and the nervous system), endoderm (inner layer becomes digestive system), mesoderm (middle layer becomes inner layers of skin, muscles, skeleton, and excretory and circulatory systems), amniotic sacs (encloses the developing embryo, protecting it and giving it a room and grow), placenta (allows oxygen, nourishment, and wastes to pass between mother and embryo), umbilical cord (connects the embryo to the placenta)
• Embryonic Period


  From 2 to 8 weeks (First 2 months), major body systems (respiratory, digestive, and nervous system) develop known as Organogenesis, critical period (most vulnerable to destructive influences), spontaneous abortion (miscarriage, expulsion from the uterus of an embryo that is unable to survive outside the womb), stillbirth (miscarriage occurred after 20 weeks of gestation, approx. 5 months), males are more likely to be spontaneously aborted or to be stillborn
• Fetal Period


  From 8 weeks to Birth, appearance of the first bone cells, final stage of gestation, grows rapidly to about 20x its previous length, finishing touches, breathe, kick, turn, etc., facial expressions of pain at 36 weeks, responds to mother's voice, fetuses know when they approach the near end of the pregnancy, grasping reflex, 6 months or more fetuses can survive outside the womb, 24-37 months babies need help in breathing
• Teratogen


  Environmental agent that can interfere with normal prenatal development
• Teratology


  Field of study that investigates the causes of birth defects