1. Floating Topic
2. ACROSOMAL REACTION & SPERM PENETRATION - sperm must penetrate oocyte covering - corona radiata & zona pellucida - sperm binds to zona p. & undergoes acrosomal reaction - enzymes are released to digest holes in zona pellucida - sperm head approaches oocyte - oocyte & sperm membranes fuse - only one sperm is allowed to penetrate oocyte (monospermy)
3. HORMONAL CHANGES DURING PREGNANCY human chorionic gonadotrophin (hCG) - secreted by trophoblast cells, later chorion - prompts corpus luteum to continue secretion of progesterone & estrogen - hCG levels rise until end of second month, then decline as placenta begins to secrete progesterone & estrogen
4. PREGNANCY events that occur from fertilization until the infant is born
   1. CONCEPTUS developing offspring
   2. GESTATION PERIOD time from last menstrual period until birth (280 Days)
   3. EMBYRO conceptus from fertilization through week 8
   4. FETUS conceptus from week 9 through birth
5. FERTILIZATION sperms chromosomes combine w/ those of secondary oocyte to form a fertilized egg (zygote
   1. FROM EGG TO ZYGOTE - oocyte is viable 12-24 hours - sperm is viable 24-48 hours after ejaculation - for fertilization to occur, coitus must occur no more than -2 days b4 ovulation -24 hrs after ovulation
6. EMBYRONIC DEVELOPMENT blastocyst: fluid filled hollow spheres Trophoblast cells - display factors that are immunosuppressive - participate in placenta formation Inner cell mass - becomes embryonic disc (embryo & 3 of embryonic membranes)
   1. CLEAVAGE -mitotic divisions of zygote - 1st cleavage @ 36 hrs = 2 daughter cells (blastomeres) - @ 72 hours = morula (16 or + cells) - @ day 3-4, embryo of ~100 cells (blastocyst( has reached uterus
   2. IMPLANTATION Blastocyst floats for 2-3 days unattached Implantation beings 6-7 days after ovulation - trophoblast adheres to site w/ proper receptors & chemical signals - inflammatory-like response occurs in endometrium Implanted blastocyst is covered over by endometrial cells Implantation is completed by 12 day after ovulation
      1. TROPHOBLASTS proliferate & form 2 distinct layers
         1. 1. CYTOBLASTS (cellular trophoblast) inner layer of cells
         2. 2. SYNCYTIOTROPHOBLAST cells in outer layer lose thier plasma membranes, invade & digest endometrium
   3. PLACENTATION formation of placenta from embyronic & maternal tissues
      1. 1. EMBRYONIC TISSUES - mesoderm cells develop from inner cell mass & line trophoblast - together these form chorion & chorionic villi
      2. 2. MATERNAL TISSUES - decidua basalis (stratum functionalis between chorionic villi stratum basalis of endometrium) develops blood-filled lacunae
   4. GASTRULATION - occurs in week 3, embryonic disc becomes a 3-layered embryo w/ ectoderm, mesoderm, & endoderm - begins w/ appearance of primitive streak, a raised dorsal groove that establishes longitudinal axis of embryo
      1. ORGANOGENESIS gastrulation sets stage for organogenesis formation of body organs & systems @ 8 weeks - all organ systems are recognizable - end of embryonic period
7. PRIMARY GERM LAYERS primitive tissues from which all body organs derive - endoderm & ectoderm are considered epithelia
   1. ECTODERM nervous system & skin epidermis
   2. ENDODERM epithelial linings of digestive respiratory, & urogenital systems
   3. MESODERM forms all other tissues
8. PATURITION giving birth to the baby labor events that expel infant from uterus
   1. STAGES OF LABOR
      1. DILATION STAGE longest stage of labor: 6-12 hrs or + initial week contractions: - 15-20 mins apart, 10-30 sec long - become more vigorous & rapid cervix effaces & dilates fully to 10 cm amnion ruptures, releasing amniotic fluid engagement occurs: head enters true pelvis
      2. EXPULSION STAGE strong contractions every 2-3 mins, about 1 min long urge to push increases (- local anesthesia) crowning occurs when largest dimension of head disterids vulva delivery of infant
      3. PLACENTAL STAGES strong contractions continue, causing detachment of placenta & compression of uterine BVs delivery of afterbirth (placenta & membranes) occurs ~30 min. after birth all placenta fragments must be removed to prevent postpartum bleeding
9. ADJUSTMENTS OF INFANT TO EXTRAUTERINE LIFE Neonatal period: 4 week period immediately after birth Physical status is assessed 1-5 mins after birth
   1. APGAR SCORE 0-2 points each for: HR, RR, color, muscle tone & reflexes - score: 8-10 (healthy)
10. LACTATION production of milk by mammary glands toward end of pregnancy - placental estrogens, progesterone, & lactogen stimulate hypothalamus to release prolactin-releasing factors (PRFs) - anterior pituitary releases prolactin Colostrum: - yellowish secretion rich in vitamin A, protein, minerals, & IgA antibodies - released first 2-3 days - followed by true milk production suckling initiates a (+) feedback mechanism oxytocin causes letdown reflex
11. FIRST BREATH increased CO2 = central acidosis= stimulates respiratory centers to trigger first inspiration - requires tremendous effort: airways are tiny & lungs are collapsed - surfactant in alveolar fluid helps reduce surface tension respiratory rate: ~45 per min for first 2 weeks, then declines