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Maternity Chapter 12
Conception and fetal development
Question | Answer |
---|---|
Conception | defined as a single union of a sperm and egg |
oogenesis | the process of egg formation |
True or False: High estrogen support motility of the uterine tube cilia to propel ovum | True |
fertilization takes place where: | in the ampulla of the uterine tube (outer third) |
morula | ball of 16-cell three days after formation of zygote |
blastocyst | formed after the morula |
6-10 days after conception | trophoblast secretes enzymes that allows it to implant into the uterus |
chorionic villi | projections that extend from the trophoblast into the endometrium for gaz exchange |
decidua | endometrium is call this after implantation |
decidua basalis, vera, and capsularis | base, middle and outer parts of the decidua in relation to the trophoblast |
Lenght of pregnancy | 10 lunar months, 9 calendar months, 40 weeks, or 280 day |
Stages of intrauterine development | ovum or preembryonic, embryo, and fetus |
ovum or preembryonic stage | This period covers cellular replication, The first two weeks of after conceptions. Blastocyst formation, initial development of the embryonic membranes, and establishment of the primary germ layers. |
Primary Germ Layers | the ectoderm, the mesoderm, and the endoderm (or entoderm) |
embryonic stage | 2 weeks to 8 weeks embryo measures 3cm critical time of development for inner and outer organs embryo vulnerable to teratogens |
oligohydramnios | less than 300ml of amniotic fluid associated with fetal renal abnormalities |
hydramnios | more than 2L of amniotic fluid associated with GI and other malformations |
content of amniotic fluid | albumin, urea, uric acid, creatinine, lecithin, sphingomyelin, bilirubin, fructose, fat, leukocytes, proteins, epithelial cells, enzymes, and lanugo hair |
yolk sac | plays a role in rbc formation during the embryonic stage (gone by week 6) |
umbilical cord is comprised of: | two arteries and one vein |
Wharton's jelly | connective tissue that prevents compression of the umbilical blood vessels to ensure nourishment to the fetus |
battledore placenta | peripheral location of the umbilical cord |
embryonic heart starts beating when: | 17 days after conception |
syncytium | functional layer of the placenta |
hCG | detected after implantation |
Fetal glucose needs | a lot higher glucose circulates through the umbilical cord |
Fetal maturation (FETAL STAGE) | From week 9 to end of pregnancy |
Problems during fetal stage | fetus is vulnerable to teratogens affecting cns functioning |
Viability | Ability of the fetus to survive threshold is 22-25 weeks |
first organ system to function in the fetus | the cardiovascular system heart beat by the end of the third week 4 to 5th week - development of the 4 chambers by the 8th week, the heart is complete |
ductus arteriosus | bypasses the lungs in the fetus |
ductus venosus | bypasses the liver and flows into the inferior vena cava |
foramen ovale | opening into the left atrium fetal blood flows directly from right to left atrium |
three special characteristics that enable the fetus to obtain sufficient oxygen from the maternal blood are: | •Fetal hemoglobin carries 20% to 30% more oxygen •The hemoglobin concentration of the fetus is about 50% greater •The fetal heart rate is 110 to 160 beats/min, making the cardiac output per unit of body weight higher than that of an adult. |
Hematopoises in the fetus | begins the 6th week in the fetal liver Rh negative mother is then at risk |
Meckel's diverticulum | the most common malformation of the midgut, occurs when a remnant of the yolk stalk that has failed to degenerate attaches to the ileum, leaving a blind sac. |
Anorectal malformations | the most common abnormalities of the digestive system. |
meconium | dark green to black, tarry fetal waste passed within 24h after birth |
storage of glycogen begins at what time in the fetus? | week 9 glycogen is 2x that of adults at birth |
When does brown fat begins accumulating? | Between 26 and 30 weeks the fetus begins to lay down stores of brown fat in preparation for extrauterine cold stress. |
bile begins forming at what time? | the 12th week bile is found is meconium |
hyperbilirubinemia | liver of fetus does not need to remove biluribin At birth, this function is needed, and the lack can cause an accumulation of bilurubin or hyperbilirubinemia |
coagulation factors | not synthesized by fetus an injection is given to the newborn |
development of the respiratory tract in fetus | week 4 to week 17 with formation of the larynx, the trachea, the bronchi, and the lung buds. week 16-24: enlargement of bronchi or formation of vessels week 24-term: type 1 and 2 cells form to secrete surfactant |
L/S ratio (Lecithin/Sphingomyelin) is used to determine what: | an L/S ratio of 2:1 signifies a mature lung this occurs at 35 weeks of gestation |
Conditions that can retard lung maturity include: | gestational diabetes and chronic glomerulonephritis intrabronchial synthetic surfactant can be used to improve an affected newborn's chance of survival |
C-Section and breathing: | Fluid is left in the newborn's lung, but reabsorbed within 2hours into circulation |
Kidney formation takes place when: | The 5th week, but begin function in the 9th week |
Kidney malformation | indicated by oligohydromnios kidney begin function right after birth Infant at risk for dehydration b/c the GFR is low at birth (glomerula filtration rate) |
when can brain waves be recorded? | by week 8 |
quickening | perception of fetal movement by week 16-20 occurs earlier in multipara than in primapara |
Sensory awareness in fetus | response to sound in by week 24 distinguish taste by the 5 month (20week) at term, fetus brain is 1/4 adult brain |
sex differentiation starts when: | after week 7 |
tested descend into scrotum when: | by week 28 |
Fontanels | Areas where more than two bones meet |
vernix caseosa | white cheesy material that protects the skin of the fetus the vernix is thick by 24 weeks, but scanty at term |
Lanugo | Very fine hair that appear first at 12 week on eyebrow and upperlips, and cover the entire body by week 20 |
immunoglobulin that crosses the placenta: | immunoglobulin G |
immonoglobulin produced bt the fetus by the end of the third trimester | IgM breast milk can give newborn some IgA |
Dizygotic twins | two ovum fertilized leading to two placentas |
Monozygotic twins | divided fertilized egg |