pregnancy

• Fertilized egg


  Implants in the uterus
• Progesterone


  Production increases to signal a pregnancy; can be detected in urine and blood
• Conception


  1. A single sperm with 23 chromosomes penetrates/fertilizes a single egg with 23 chromosomes

  2. The resulting cell, a zygote, now has 46 chromosomes
• Zygote


  The cell begins dividing and is also called a blastocyst
• Embryo


  From week 2-8
• Embryo


  • Suspended in an amniotic sac surrounded by fluid during the 280 day gestation period
  • Umbilical cord attached at the navel connects it to the placenta, where it gets nutrients and oxygen
• Pregnancy trimesters


  1. 1st trimester: all parts of the embryo are formed

  2. 2nd trimester: all parts start to function

  3. 3rd trimester: the embryo is now called a fetus, and the main task is growth
• Vernix caseosa


  Cheesy coating that protected the skin before birth
• Lanugo


  Downy hair that protected the skin before birth
• APGAR scale


  Evaluates the health of the newborn based on color, heartbeat, reflexes, muscle tone, and breathing (scored 0-10)
• Labor


  Characterized by muscle contractions, dilation (to 10 cm) and effacement (thinning) of the cervix, and expulsion of the mucous plug
• Cephalic delivery


  Head-first delivery, the most common
• Breech delivery


  Backward presentation
• Caesarian delivery


  Delivery through an incision in the abdomen
• After birth


  1. Umbilical cord is cut and clamped

  2. Placenta (afterbirth) is delivered following birth of the baby
• Placenta previa


  Development of the placenta over the opening of the cervix
• Preeclampsia


  Pregnancy-induced hypertension (high blood pressure)
• Spontaneous abortion or miscarriage

  Loss of a fetus during the first 20 weeks, often due to abnormalities, trauma, or lifestyle choices
• Zygote


  Forms when a sperm and a secondary oocyte unite
• Prenatal development


  Begins with the formation of the zygote and continues for 38 weeks until birth
• Growth


  Increase in size
• Development


  Continuous process by which an individual changes from one life phase to another, including growth
• Prenatal period


  From fertilization to birth
• Postnatal period


  From birth to death
• Pregnancy


  The presence of a developing offspring in the uterus
• Trimesters


  Three periods, each three months long, that pregnancy is divided into
• Transport of sex cells

  1. A secondary oocyte must be ovulated and enter a uterine tube

  2. Only 200 of the 200 to 600 million sperm reach a secondary oocyte
• Fertilization


  The union of an egg cell (secondary oocyte) and a sperm cell
• Prenatal period


  Usually lasts 38 weeks from conception
• Prenatal period stages


  1. Period of cleavage

  2. Embryonic stage

  3. Fetal stage
• Cleavage


  The rapid cell division and distribution of the zygote's cytoplasm into progressively smaller cells
• Blastomeres


  The cells produced during cleavage
• Hormonal changes during pregnancy

  1. Secretion of hCG maintains the corpus luteum

  2. The corpus luteum secretes estrogens and progesterone

  3. The placenta secretes large amounts of estrogens and progesterone

  4. Estrogens and progesterone stimulate and maintain the uterine lining, inhibit FSH and LH, inhibit uterine contractions, and enlarge the reproductive organs

  5. Relaxin from the corpus luteum inhibits uterine contractions and relaxes the pelvic ligaments

  6. Placental lactogen stimulates breast development

  7. Aldosterone promotes sodium retention

  8. PTH maintains calcium concentrations in the blood
• Trophoblast cells


  1. Secrete hCG

  2. hCG maintains corpus luteum

  3. Corpus luteum continues to secrete estrogens and progesterone

  4. Estrogens and progesterone promote growth, development, and maintenance of uterine wall
• Changes during pregnancy


  • Growth of the uterus can displace abdominal organs and disrupt meals, including the development of heartburn and increased urinary frequency
  • More oxygen is needed and more waste is excreted causing increases in blood volume, cardiac output, breathing rate, and urine production
  • Intake must be sufficient to supply needed vitamins, minerals and proteins
• Embryonic stage


  Extends from the beginning of the second week through the eighth week, when the placenta forms, the main internal organs develop, and the major external body structures appear
• Fetal stage


  Begins at the end of the eighth week of prenatal development, growth is rapid, and body portions change considerably
• Birth defects


  Can have various causes
• Fetal blood and circulation


  Specific details
• Birth process


  Pregnancy terminates with the birth process called parturition, which is complex