anatomy

• Menstrual cycle phases


  1. Follicular

  2. Preovulatory

  3. Ovulation

  4. Postovulatory-Luteal
• Follicular phase


  • Estrogens, inhibin, relaxin and progesterone low
  • Endometrial lining sloughs off
  • GnRH and FSH increased
  • Several growing follicles stimulated to mature
• Preovulatory phase


  • Estrogens and inhibin increases due to dominant follicle
  • FSH decreases due to estrogens and inhibin negative feedback
  • Endometrium stimulated to proliferate
  • Degeneration of nondominant follicles
• Ovulation


  • Increasing estrogen stimulates GnRH to stimulate LH production drastically
  • Primary oocytes complete meiosis I
  • Follicle secretes digestive enzyme and prostaglandins
  • Ovulation mediated by follicular enzymes and prostaglandin
• Postovulatory-Luteal phase


  • Corpus luteum continues to secrete progesterone and estrogens
  • FSH and LH inhibited
  • Secretory endometrium develops
  • No new follicles develop
• Postovulatory-Luteal phase (continued)


  • Estrogens and progesterone decrease
  • Endometrium begins to slough off
  • New cycle begins
  • Corpus luteum degenerates into corpus albicans
• Fertilization and implantation


  1. Oocyte encapsulated by corona radiata and zona pellucida

  2. Sperm capacitation

  3. Sperm penetrates zona pellucida and undergoes acrosomal reaction

  4. Sperm nucleus fuses with oocyte nucleus to form zygote

  
• Early embryo development


  1. Rapid mitotic cell divisions (cleavage)

  2. Morula stage

  3. Blastocyst stage

  4. Implantation in endometrium

  
• Parturition (labor)


  1. Uterine contractions increase in frequency and intensity

  2. Cervix dilates

  3. Expulsion of baby

  4. Placental stage - placenta expelled
• Mammary glands


  • Located in breast
  • Each breast has one nipple and areola
  • Consist of 15-20 lobes with epithelial cells that secrete milk
  • Milk drains into milk ducts
• Hormonal regulation of lactation

  1. Prolactin promotes milk production

  2. Estrogen and progesterone inhibit prolactin through prolactin inhibiting hormone

  3. Suckling stimulates prolactin and oxytocin release

  4. Oxytocin stimulates milk ejection
• Oocyte is viable for 12-24 hours
• Sperm is viable for 24-72 hours
• Fertilization can occur up to 3 days before ovulation or 24 hours after ovulation
• An ovulated oocyte is encapsulated by the corona radiata and zona pellucida
• Sperm capacitation


  Functional changes that cause the sperm tail to beat vigorously and prepare its plasma membrane to fuse with the oocyte's plasma membrane

  
• Sperm penetration of oocyte

  1. Sperm penetrates zona pellucida

  2. Acrosomal enzymes digest zona pellucida

  3. Sperm nucleus fuses with oocyte nucleus

  
• Placenta starts providing nutrition after 16 days of fertilization
• Placental functions


  • Diffusion of gases, nutrients, and waste
  • Secretion of hCG, estrogen, progesterone, and human chorionic somatomammotropin
• hCG


  Maintains corpus luteum and promotes estrogen and progesterone secretion
• Placental estrogen


  30 times higher than follicular estrogen production
• Functions of estrogen during pregnancy


  • Enlargement of uterus, breasts, and female external genitalia
  • Relaxation of pelvic ligaments
• Functions of progesterone during pregnancy


  • Development of decidual cells in endometrium
  • Decreases uterine contractility
  • Increases nutrient production in fallopian tubes and uterus
  • Prepares breasts for lactation
• Maternal physiological changes during pregnancy

  • Uterus weight increases 20x
  • Breast enlargement and milk production ability
  • 30% increase in blood volume and cardiac output
  • 20% increase in respiratory rate
  • Increased nutritional needs and basal metabolic rate
  • 10-14 kg average weight gain
• Parturition (labor)


  1. Uterus becomes more excitable with increased estrogen:progesterone ratio

  2. Braxton Hicks contractions increase

  3. Cervical stretching stimulates oxytocin release

  4. Oxytocin and prostaglandins further increase uterine contractions

  5. Strong uterine and abdominal contractions expel the baby
• Stages of labor


  1. Dilation stage - cervix dilates to 10 cm

  2. Expulsion stage - delivery of the baby

  3. Placental stage - placenta expelled
• Mammary gland structure


  • 15-20 lobes separated by adipose and connective tissue
  • Epithelial cells secrete milk into milk ducts