1. Chapter 18 Learning Targets 1. Explain the process of fertilization and the conversion of egg into a zygote. 2. Name & give the function of the 4 extra embryonic membranes. 3. Describe the structures & functions of the placenta & umbilical cord. 4. Describe the events that occur during pre-embryonic and embryonic development. 5. Describe the events that occur during fetal development. 6. Describe the 3 stages of birth. 7. Describe the anatomy of the breast & the suckling reflex.

2. Explain the process of fertilization and the conversion of egg into a zygote. LT#1 Upper third of fallopian tube One sperm penetrates the egg = NO VACANCY! Sperm nucleus fuses with egg nucleus = fertilization is complete = zygote Zygotes begins to divide as it migrates to ward the uterus Embeds in uterine lining (endometrium) = pregnant

3. Name & give the function of the 4 extra embryonic membranes. LT#2 1. Amnion 2. Chorion 3. Yolk sac 4. Allantois See page 366

4. Amnion Yolk sac Allantois

5. Name & give the function of the 4 extra embryonic membranes. LT#2 1. Amnion - provides an inner fluid environment 2. Chorion – the outer membrane that becomes part of the placenta = where fetal blood XΔs molecules with maternal blood 3. Yolk sac - nutrient material, first site of red blood cell (rbc) formation & becomes part of umbilical cord 4. Allantois - contributes to the circulatory system – its vessels become umbilical b.v. that transport fetal blood to & from placenta (pg 243)

6. Describe the structures & functions of the placenta & umbilical cord. LT#3 2 portions: (1) fetal = chorionic tissue (2) maternal = uterine tissue (pg 367) chorionic villi Cover the entire surface of chorion until 8 th week & are surrounded by maternal blood & XΔ of materials takes place ax placental membrane BUT maternal blood does not mix with fetal blood Diffusion of O2, glucose, aa from maternal  fetal / CO2, wastes fetal  maternal

7. Describe the structures & functions of the placenta & umbilical cord. LT#3 Umbilical cord transports fetal blood to & from placenta Contains fetal arteries & vein to transport waste out & nutrients in HCG = human chorionic gonadotropic hormone is produced by chorion & then placenta prevents corpus luteum from dying = no menstruation Placental estrogen & progesterone take over for corpus luteum later on to maintain pregnancy

8. Describe the events during pre-embryonic & embryonic development. LT#4 First week Zygote divides repeatedly post fertilization to become morula = compact ball of cells Morula becomes hollow blastocyst with an inner cell mass surrounded by an outer layer = trophoblast (future chorion)

9. Describe the events during pre-embryonic & embryonic development. LT#4 2 week – 8 th week 2. Implantation / tissues present 3. Nervous system begins / placenta well formed 4. Limb buds / beating heart / tail 5. Big head / curved / nose, eyes, ears noticeable 6. Fingers & toes / cartilaginous skeleton 7. Bone replacing cartilage 8. Facial features refined / 1 ½ inches long

10. http://embryology.med.unsw.edu.au/Medicine/FlectureEmbryo.htm http://www.youtube.com/watch?v=UgT5rUQ9EmQ http://www.youtube.com/watch?v=aOY16GlqrPw&NR=1

11. Describe the events that occur during fetal development. LT#5 3 rd to 9 th month 3. Gender distinguishable / fingernails 4. Skeleton visible / hair appears 5. White protective coating / heartbeat audible / 6 inches & 6 ounces 6. Body covered with fine hair / red, wrinkled skin 7. Testes descend / eyes open / 12 inches & 3 lbs 8. Body hair disappears / subcutaneous fat deposited 9. Birth imminent / 21 inches

12. Describe the 3 stages of birth. LT#6 Birth = parturition 1. Cervix dilates 2. Baby is born 3. Delivery of placenta

13. Cervix dilates – stage 1 Contractions cause cervical canal to disappear = effacement Water breaks Baby’s head acts as a wedge to further assist dilation to 10 cm (see board!)

14. Baby is born – Stage 2 Uterine contractions every 1 – 2 minutes lasting about 1 minute each Desire to push Baby’s head turns so back of head is uppermost Episiotomy to expand vaginal opening Once head is delivered baby turns it to the side allowing delivery of the shoulders one at a time When breathing normally cord is cut

15. Delivery of placenta – Stage 3 Afterbirth 15 minutes or so after baby Uterine muscles contract, shrink uterus and dislodge placenta Once placental membranes are delivered birth or parturition is complete

16. Describe the anatomy of the breast & the suckling reflex. LT#7 Breasts contain 15 – 25 lobules each with its own milk duct Ducts begin at nipple and divide into many other ducts that end in blind sacs called alveoli Ducts enlarge during pregnancy, increasein # & size Maternal hormones affect fetus and baby can sometimes produce milk when newborn No lactation during pregnancy – hormone prolactin is needed Produced by pituitary after delivery Colostrum first – milk after 5 days

17. Suckling reflex Continued lactation requires suckling child Suckling stimulates nerve endings in areola sending impulses to brain (hypothalamus) which directs the pituitary to produce oxytocin When oxytocin arrives at the breast it stimulates the lobules to contract & milk flows into ducts = “let down” & easily drawn out by child More suckling  more oxytocin  more milk Other oxytocin benefits = uterine shrinkage & bonding