3Pregnancy Learning Outcomes 1. Describe fertilization and the early development of the fertilized egg.2. Describe the structure and function of the placenta.3. Describe how fetal circulation differs from adult circulation.4. Briefly describe changes that occur in the embryo, fetus, and mother during pregnancy.
5Pregnancy Gestation begins with fertilization and ends with delivery Approximately 38 weeksAll fetal tissues differentiate from single fertilized egg
6Fertilization and the Start of Pregnancy Vagina receives semenSperm dissolve egg cell coating, penetrate plasma membraneSperm, egg combine in single cell (zygote)Zygote divides into cell cluster, moves to uterusCluster becomes embryo
7Figure 24-1 The female reproductive system. Where is the ovum fertilized?
8The PlacentaOrgan of nutrition, respiration, excretion for developing offspringEmbryonic cluster forms villi (projections)Projections invade uterine wall, maternal blood channels (venous sinuses)Embryonic layer and uterine lining form placenta
9The Umbilical Cord Connects embryo to placenta Carries blood to and from fetusFetus has special circulatory features
10Fetal CirculationCirculatory adaptations to bypass nonfunctional lungsUmbilical vein from mother carries blood to liverMost blood added to deoxygenated blood in inferior vena cava via ductus venosusForamen ovale in atrial septum bypasses right ventricle and pulmonary circuitDuctus arteriosus connects pulmonary artery to descending aortaTwo umbilical arteries return blood to placenta for oxygenationAdaptations close after birth of baby. Failure to close results in congenital defects.
11Figure 24-2 Fetal circulation and section of placenta. What is signified by thepurple color in this illustration?11
13✓PregnancyCheckpoints 24-1 What structure is formed by the union of an ovum and a spermatozoon? 24-2 What organ nourishes the developing fetus? 24-3 What is the function of the umbilical cord? 24-4 Fetal circulation is adapted to bypass what organs?13
14Hormones and Pregnancy Human chorionic gonadotropin (hCG)ProgesteroneEstrogenHuman placental lactogen (hPL, Relaxin)
16Development of the Embryo Embryology is study of growth during first 8 weeks of lifeNervous system begins to formHeart and blood vessels originateLimb buds formHuman appearance
17Development of the Fetus Offspring from month 3 until birthOrgans grow and matureOvaries formMost rapid growth months four to six (second trimester)Can determine sexAmniotic sacVernix caseosa
18Figure 24-3 Development of an embryo and early fetus. 18
19Figure 24-4 Human embryos at different stages and early fetus. 19
20Metabolic Changes in the Mother Heart pumps more bloodLungs increase respirationKidneys excrete waste from fetus and motherDigestive system supplies additional nutrientsNausea and vomiting commonUrinary frequency and constipation common
21Figure 24-5 Midsagittal section of a pregnant uterus with intact fetus. What structure connects thefetus to the placenta?21
22The Use of Ultrasound in Obstetrics Safe, painless, noninvasive method used toDiagnose pregnancyJudge fetal ageDetermine location of placentaShow presence of excess amniotic fluid and fetal abnormalities
24Figure 24-7 Comparison of positive and negative feedback. What possible forces can stopa positive feedback system?24
25✓PregnancyCheckpoints 24-5 At about what time in gestation does the heartbeat first appear? 24-6 What is the name of the fluid-filled sac that holds the fetus? 24-7 What is the approximate duration of pregnancy in days from the time of fertilization?25
30Cesarean SectionIncision made in abdominal wall and uterine wall for fetal deliveryMay be required forPlacental abnormalityAbnormal fetal positionDisproportion between head of fetus and mother’s pelvis
31Multiple Births Two Types of Twins Fraternal Two different ova Two placentas and surrounding sacsIdenticalSingle ovumEmbryonic cells separate into two unitsUsually single placentaSeparate umbilical cordsAlways same sex
32Pregnancy Outcomes Live birth Immature (premature) infant Loss of fetusAbortionFetal deathStillbirth
46Disorders of Pregnancy, Childbirth, and Lactation ✓Disorders of Pregnancy, Childbirth, and LactationCheckpoints What is an ectopic pregnancy? What is puerperal infection?46
47Case Study Learning Outcome 8. Referring to the case study, describe some of the events that occur during each phase of labor.47
48Case Study Events That Occur During the Phases of Labor Stage 1: Cervix dilates, contractions beginStage 2: Cervix is fully dilated, contractions severe, baby is deliveredStage 3: Delivery of placentaStage 4: Uterine contractions to return uterus to pre- pregnancy size and shape
49Word Anatomy Learning Outcome 9. Show how word parts are used to build words related to development and birth49
50Word Anatomy Word Part Meaning Example zyg/o joined An ovum and spermatozoon join to form a zygote.chori/omembrane, chorionHuman chorionic gonadotropin is produced by the chorion (outermost cells) of the embryo.ox/ysharp, acuteOxytocin is a hormone that stimulates labor.toc/olaborSee preceding example.ect/ooutside, externalAn ectopic pregnancy occurs outside of the uterine cavity.